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The putative membrane (M) protein (ORF 6) and nucleocapsid (N) protein (ORF 7) genes of five U.S. isolates of porcine reproductive and respiratory syndrome virus (PRRSV) with differing virulence were cloned and sequenced. To determine the genetic variation and the phylogenetic relationship of PRRSV, the deduced amino acid sequences of the putative M and N proteins from these isolates were aligned, to the extent known, with other PRRSV isolates, and also other members of the proposed arterivirus group including lactate dehydrogenase-elevating virus (LDV) and equine arteritis virus (EAV). There was 96–100% amino acid sequence identity in the putative M and N genes among U.S. and Canadian PRRSV isolates with differing virulence. However, their amino acid sequences varied extensively from those of European PRRSV isolates, and displayed only 57–59% and 78–81% identity, respectively. The phylogenetic trees constructed on the basis of the putative M and N genes of the proposed arterivirus group were similar and indicated that both U.S. and European PRRSV isolates were related to LDV and were distantly related to EAV. The U.S. and European PRRSV isolates fell into two distinct groups, suggesting that U.S. and European PRRSV isolates represent two distinct genotypes. |
A single radial haemolysis (SRH) for reovirus antibody determination was developed and compared to standard haemagglutination-inhibition (HI) and complement fixation (CF) techniques. SRH appeared more simple and sensitive than CF, but less sensitive and less specific than HI. |
Baby rabbits surviving infection with pleural effusion disease virus (PEDV) developed viraemia persisting for at least six months. Only the infectious serum samples collected during the first 2 months of disease could transfer the typical PED. Six months after neonatal infection, virus concentration in serum was 10(2) to 10(4) rabbit-infectious doses per ml, the level of IgG appeared elevated, and serum rendered non-infectious by ether-treatment had a protective effect in passive immunisation experiments. No evidence of glomerulonephritis or deposits of immunoglobulins could be demonstrated in the kidneys. During the nursing period PEDV was transmitted from infected baby rabbits to two out of four dams, but not to control litter-mates. After the nursing period control rabbits, caged together with the viraemic rabbits for 60 to 150 days, remained free from PEDV infection. |
After intranasal inoculation of suckling rats mouse hepatitis virus multiplied mostly in the nasal epithelium; though there were no symptoms, antibodies were produced. Antibodies were also demonstrated in adult rats. These findings suggest that the rat may be a natural host for the virus. |
Transmissible gastroenteritis virus was administered orally to cats. No clinical disease resulted but infectious virus was isolated from faeces for up to 22 days after infection and serum antibody was detected by neutralisation and immunofluorescence tests. |
Retroviruses are classified as exogenous and endogenous retroviruses according to the mode of transmission. Endogenous retroviruses (ERVs) are retroviruses which have been integrated into germ-line cells and inherited from parents to offspring. Most ERVs are inactivated by deletions and mutations; however, certain ERVs maintain their infectivity and infect the same host and new hosts as exogenous retroviruses. All domestic cats have infectious ERVs, termed RD-114 virus. Several canine and feline attenuated vaccines are manufactured using RD-114 virus-producing cell lines such as Crandell-Rees feline kidney cells; therefore, it is possible that infectious RD-114 virus contaminates live attenuated vaccines. Recently, Japanese and UK research groups found that several feline and canine vaccines were indeed contaminated with infectious RD-114 virus. This was the first incidence of contamination of ‘infectious’ ERVs in live attenuated vaccines. RD-114 virus replicates efficiently in canine cell lines and primary cells. Therefore, it is possible that RD-114 virus infects dogs following inoculation with contaminated vaccines and induces proliferative diseases and immune suppression, if it adapts to grow efficiently in dogs. In this review, we summarize the incidence of contamination of RD-114 virus in live attenuated vaccines and potential risks of infection with RD-114 virus in dogs. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00705-013-1809-1) contains supplementary material, which is available to authorized users. |
INTRODUCTION: Acute respiratory tract infections (ARI) in children are often treated with antibiotics even without evidence of bacterial infection. Serum procalcitonin (PCT) is elevated in bacterial but not in viral infections. PATIENTS AND METHODS: We performed a retrospective analysis of children in the PID-ARI.net study on respiratory infections to address the question of whether plasma PCT could potentially distinguish between bacterial infections requiring antibiotic therapy and viral ARI. We analysed data on 327 children who had been included in the German PID-ARI.net study and in whom nasopharyngeal aspirates had been analysed with a 19-valent multiplex reverse transcription-polymerase chain reaction–enzyme-linked immunosorbent assay for viral and atypical bacterial pathogens. Serum PCT was determined using a quantitative immunoassay (BRAHMS Kryptor PCTsensitive, Henningsdorf, Germany). We then focussed specifically on those children who were treated with antibiotics and therefore had been suspected of having bacterial infection but who had a serum PCT level lower than 0.1 ng/ml. RESULTS: Out of 327 children, 132 had serum PCT levels below 0.1 ng/ml. Of these 132, 38 children had been treated with antibiotics. After exclusion of 26 patients (with critical illnesses, antibiotics on admission or for reasons other than ARI), 12 children remained for further evaluation. Of these 12 children, four had atypical pneumonia; four others had positive virus testing, and, in the last four, the aetiology of ARI remained unknown; evidence of bacterial infection could not be detected in any. CONCLUSIONS: Taken the results of this retrospective analysis, serum PCT values below 0.1 ng/ml might be a marker to identify children with acute respiratory tract infection in whom antibiotic treatment could be withheld. However, only a prospective intervention trial will prove the general safety of this limit. |
Two fractions of herpes simplex virus glycoprotein gC were isolated and characterized by means of immunosorbent-purification with monoclonal antibodies against gC and Helix pomatia lectin (HPA) affinity chromatography. About 25 per cent of the glycoprotein gC population demonstrated affinity for the lectin, compatible with presence of N-acetylgalactosamine as terminal sugar of the oligosaccharide. The HPA-binding populations of gC appeared as two electrophoretic bands with lower molecular weights than the non-binding gC. The gC subfraction without affinity for the HPA was subjected to treatments aiming to desialylize the carbohydrate moiety. Only 5 per cent of the initially non-reactive fraction of gC became reactive to HPA after the treatments, suggesting that masking of penultimate N-acetylgalactosamine by sialic acid was not a main reason for lack of HPA affinity. Results of treatment with alkaline Na BH(4) demonstrated presence of oligosaccharide-peptide linkages sensitive to β-elimination suggesting O-glycosidic type of linkage. The subfraction of gC demonstrating affinity for HPA as well as gC devoid of HPA binding capacity both revealed affinity for Con A. Therefore N-glycosidically as well as O-glycosidically linked oligosaccharides seemed to be present on the one and same glycoprotein. On the basis of the results presented we assume that the glycosylation of HSV glycoprotein gC may lead to, at least, two populations of the glycoprotein gC, one with terminal N-acetylgalactosamine residues of oligosaccharides 0-glycosidically linked to the polypeptide and the other without affinity for HPA. However, both populations of gC contain similar proportions of oligosaccharides of the high mannose or complex types with N-glycosidic carbohydrate-peptide linkages as indicated by their affinity for Con A. |
Thirteen monoclonal antibodies (MAbs) to the glycoprotein (G) of vesicular stomatitis virus (VSV) serotype Indiana were prepared and examined for their effects on various biological activities of VSV, including in vitro infection, hemagglutination, adsorption to cells, and mediation of cell fusion. Competitive binding assays with these MAbs revealed the presence of at least seven distinct antigenic determinants (epitopes) on the G protein. In some cases, overlappings among epitopes to various degrees were observed as partial inhibition or binding enhancement. The MAbs to all the epitopes but one (epitopes 1–6) reacted with the denatured G protein in a Western immunoblot analysis. Four of the epitopes (epitopes 2, 4, 5, and 7) were involved in neutralization and two (epitopes 1 and 2) in hemagglutination inhibition. None of the MAbs inhibited the adsorption of radiolabeled VSV to BHK-21 cells; the MAbs to epitope 2 slightly enhanced the virus adsorption. All neutralization epitopes except epitope 2 (epitopes 4, 5, and 7) were associated with inhibition of VSV-mediated cell fusion. These results show a direct spatial relationship between the epitopes recognized by the MAbs and functional sites on G protein and further insights into the structure and function of G protein. |
MHV3 has three distinct effects in different strains of mice: strain A mice are completely resistant, most strains (including C57BL, DBA/2, BALB/c and NZB strains) die of acute hepatitis whereas in certain strains (eg. C3H and A2G) the virus produces a persistent infection with neurological symptoms. In cultures of peritoneal macrophages from susceptible strains, MHV-3 replicated freely, with giant cell formation. No replication was observed in macrophages from strain A mice. In contrast to this full susceptibility or resistance, macrophage cultures from strains of mice in which persistent infections occur showed an intermediate susceptibility, as judged by the intensity of the cytopathic effect, the presence of viral antigens in the cytoplasm and levels of viral replication. Possible ways in which the intermediate susceptibility of macrophages and persistent infections might be related are discussed. |
To test the feasibility of gene therapy for AIDS patients, an animal model is needed to evaluate the efficacy and safety of this approach. Antiviral genes (encoding antisense RNA or viral protein) derived from Simian immunodeficiency virus (SIV) were efficiently targeted into CD4+ lymphocytes through retroviral-mediated gene transfer. After challenging with infectious viruses, the transduced lymphocytes that received antiviral genes were not only protected from SIV infection, but also from infection with HIV, for at least 25 days. Furthermore, little or no cytolytic effect (syncytium formation) was observed in the protected cells. These data demonstrated that SIV or HIV replication could be effectively blocked by antisense sequence(s) or negative dominant factors which were introduced into targeted cells through retroviral-mediated gene transfer. |
ABSTRACT: Epithelial transport and degradation of horseradish peroxidase (HRP), a macromolecular tracer, was studied in conventional and germ-free suckling mice following an experimental infection with rotavirus. Conventional and germ-free mice developed diarrhea from days 2 to 8 postinfection (pi), with growth failure. In mucosal homogenates, infectious virus detected by immunofluorescence on MA 104 cells was present from day 2 through day 8 pi in germ-free mice, but persisted longer (day 13 pi) in conventional mice. Only mild histological lesions were observed during diarrhea, but obvious macrovacuolation of epithelial cells and increased cellular density occurred during the convalescence period (days 9 to 13 pi). Intact and degraded HRP fluxes from mucosa to serosa were measured in vitro on segments of jejunum mounted in Ussing chambers. Both groups of mice developed increased HRP permeability during the experimental period, but at different times after inoculation: during the diarrheal period (days 2 and 3 pi) conventional mouse epithelium absorbed five times more HRP than noninfected controls and during the convalescence period (days 9 to 13 pi) HRP absorption in germ-free mice rose 10-fold as compared to its level before infection. In both cases, this increase in HRP permeability was entirely due to an increase in intact HRP absorption, probably via a transcellular route, and occurred without any alteration in degraded HRP transport. These results indicate that in mice, rotavirus infection causes a transient rise in gut permeability to undegraded proteins. The intestinal microflora seems to affect the timing, magnitude, and duration of this increased permeability. |
The substrate requirement for rubella virus protease trans-activity is unknown. Here, we analyzed the cleavability of RV P200-derived substrates varying in their N-terminal lengths (72–475 amino acids) from the cleavage site by the RV protease trans-activity. Only substrates with at least 309 amino acid residues N-terminal to the cleavage site were able to undergo cleavage. Further, rubella sequence was found to be necessary in the N-terminal region of the substrate, whereas a heterologous sequence C-terminal to the cleavage site was tolerated. These results demonstrated a requirement for residues located between amino acids 994–1102 of the RV P200 polyprotein, besides its cleavage site for RV protease trans-activity. This region overlaps with the starting site of the essential cis-protease activity of RV P200 polyprotein. This is a novel observation for a viral protease of the family Togaviridae. |
Sequence comparisons predicted a potential papain-like proteinase domain in the N-terminal cleavage product (NRP) of the large nonstructural replicase polyprotein (RP) of turnip yellow mosaic virus (TYMV). Replacement of the predicted catalytic amino acids, Cys-783 by Ser, or of His-869 by Glu, abolished cleavage of the 206K RP into a ∼150K NRP and a ∼78K C-terminal product in reticulocyte lysates, while other substitutions exerted no apparent influence on proteolysis. The proteinase-deficient mutant RPs could not be cleaved in trans by as much as an eight-fold molar excess of wild-type proteinase. Deletion experiments have excluded the possible influence on autoproteolysis of amino acid sequences 1–708 and 982–1204 flanking the proteinase domain. Thus, the proteinase of TYMV with a papain-like dyad of essential amino acids has been mapped just upstream from the putative NTPase domain. Statistically significant sequence similarities with the TYMV proteinase were found for the similarly located domains of the replicase polyproteins of carlaviruses, capilloviruses, apple stem pitting virus and apple chlorotic leaf spot virus as well as for those of other tymoviruses and for the domain located downstream from the putative NTPase domain of the large polyprotein of beet necrotic yellow vein furovirus. All these domains are not significantly similar to other known proteinases, although they conserve papain-like Cys- and His-containing motifs. Thus these domains constitute a compact group of related enzymes, the tymo-like proteinases, within the proposedpapainlike proteinase supergroup. The resulting alignment of 10 tymo-like proteinase sequences has revealed a third highly conserved residue — Gly (Gly821 in TYMV RP) followed by a hydrophobic residue. We speculate that all the tymo-like proteinase domains of the viral replicative proteins may share common biochemical and biological features. |
Feline bocavirus (FBoV) has been classified into three genotypes (FBoV1-FBoV3). FBoVs are mainly detected in feces. In the present study, we collected rectal swabs from cats in Japan and examined the samples for the presence of FBoV. The FBoV infection rate was 9.9 % in 101 cats. No significant association was observed between FBoV infection and clinical symptoms. Based on the full-length NS1 protein, the three strains of FBoVs detected in the present study shared high homologies with the genotype 2 FBoV POR1 strain. This is the first study to report FBoV in Japan. |
The nucleotide sequence of the coat protein genes and 3′ non-coding regions of two different resistance-breaking tobamoviruses in pepper have been determined. The deduced coat protein of an Italian isolate of pepper mild mottle virus (PMMV-I) consists of 156 amino acids and its 3′ non-coding region is 198 nucleotides long. They have been found to be very similar in sequence and structure to those previously reported for a Spanish isolate (PMMV-S). In contrast, a Dutch isolate termed P 11 codes for a coat protein of 160 amino acids and its 3′ non-coding region is 291 nucleotides long, which may have arisen by duplication. The nucleotide and the predicted coat protein amino acid sequence analysis show that this isolate should be considered as a new virus within the tobamovirus group. The term paprika mild mottle virus (PaMMV) is proposed. |
Molecular weights of six major polypeptides of infectious bronchitis virus (IBV) are: 1. 75,000; 2. 50,000; 3. 45,000; 4. 35,000; 5. 28,000 or 24,000, and 6. 22,000 dalton. According to the mobility of protein 5 the polypeptide patterns of IBV serotypes fall into two main categories. |
Mouse hepatitis virus 3 (MHV-3) is highly hepatotropic in sensitive mice. Temperature-sensitive mutants (ts mutants) induced by N-methyl-N′-nitrosoguanidine and 5-fluorouracil were isolated. Twelve mutants which were able to induce the formation of syncytia at 33°C but not at the restrictive temperature (39.5°C) were selected for detailed study. No viral RNA synthesis was detected after infection at the restrictive temperature with six of the mutants (RNA(−)) whereas six others were RNA(+), although they displayed RNA synthesis which was generally reduced. No differences have been detected in the size of the genome or the viral-intracellular RNA species found in wild type virus or ts mutant infected cells at permissive temperature. The pattern of virus-induced proteins analyzed after immunoprecipitation by SDS-PAGE was similar in wild type virus and RNA(+) mutant infected cells at 39.5°C. Complementation experiments between ts mutants enabled us to distinguish five groups. Three of the groups contained RNA(−) mutants and two of them RNA(+). Plaques made by mutants in one group displayed characteristic features that distinguished them from the wild type. |
Among all the neural cells in fetal rat brain culture developing neurons showed the highest rate of infection by Japanese encephalitis virus (JEV). JEV specifically bound to these cells as measured by immuno-staining. These results indicate that developing neurons are the major target of JEV, and that the initial specific binding of virus to these cells may be one of the reasons for the neurotropism of JEV. |
This study investigated the abilities of cDNA probes from the 5′ and 3′ ends of the genome of human rhinoviruses (HRV-) 14, 9, and 1B to detect RNA from 59 rhinovirus serotypes. The results show that probes from the 5′ end of the genomes of HRV-14, 9, and 1B detected a large number of serotypes but the detection rate was variable and depended on the degree of homology with the particular probe. In contrast, all the 3′ end probes were specific for the homologous virus. However, along HRV-9 probe detected a large number of serotypes. It was concluded that such cDNA probes would not detect all serotypes with equal efficiency. Synthetic oligonucleotides corresponding to short but highly conserved regions in the 5′ non coding region may overcome this problem. |
Influenza strains produced by recombination and tested as possible live vaccine candidates were studied in organ cultures of trachea. Two strains which proved to be too virulent in human volunteers regularly caused damage to the ciliated epithelium and viruses grew to high titre. Two strains which proved to be attenuated for volunteers did not cause appreciable damage, although they replicated to low titre in the epithelium. Similar results were obtained with influenza A virus attenuated by passage in the presence of horse sera. The method may be of value for detecting virulent live influenza vaccine candidates without risking severe illness in volunteers. |
Junin virus (JV) infected Vero cells were used to investigate virus capacity to induce cell-cell fusion. Polykaryocyte formation due to JV was found to be pH and temperature-dependent. A reduced fusion activity was detected on BHK-21 cells. Different JV-strains exhibited a similar extent and pH dependence of their fusion activity. Neutralizing antibodies against the main viral glycoprotein (GP38) inhibited syncytium production and GP38 conformational changes in response to acid treatment were detected by an immunoprecipitation assay. |
Torque teno sus virus 1 (TTSuV1) is a novel virus that has been found widely distributed in the swine population in recent years. Analysis of codon usage can reveal much about the molecular evolution of TTSuV1. In this study, synonymous codon usage patterns and the key determinants in the coding region of 29 available complete TTSuV1 genome sequences were examined. By calculating the nucleotide content and relative synonymous codon usage (RSCU) of TTSuV1 coding sequences, we found that the preferentially used codons were mostly those ending with A or C nucleotides; less-used codons were mostly codons ending with U or G nucleotides, and these were mainly affected by composition constraints. Although there was a variation in codon usage bias among different TTSuV1 genomes, the codon usage bias and GC content in the TTSuV1 coding region was lower, which was mainly determined by the base composition in the third codon position and the effective number of codons (ENC) value. Moreover, the results of correspondence analysis (COA) indicated that the codon usage patterns of TTSuV1 isolated from different countries varied greatly and had significant differences. In addition, Spearman’s rank correlation analysis and an ENC plot revealed that apart from mutation pressure, which was critical in determining the codon usage pattern, other factors were involved in shaping the evolution of codon usage bias in TTSuV1, such as natural selection. Those results suggested that synonymous codon usage patterns of TTSuV1 genomes were the result of interaction between mutation pressure and natural selection. The information from this study not only provides important insights into the synonymous codon usage pattern of TTSuV1, but also helps to identify the main factors affecting codon usage by this virus. |
In this study, the susceptibility of porcine peripheral blood monocytes (BMo), peritoneal macrophages (PMφ) and alveolar macrophages (AMφ) to PRRSV was examined. To test the effect of differentiation and activation on their susceptibility, AMφ and BMo were aged, cultivated in either adhesion or suspension and treated with bacterial lipopolysaccharide (LPS) and phorbol myristate acetate (PMA). It was found that freshly isolated PMφ and BMo were non-permissive to PRRSV. PMφ remained refractory but a few BMo became susceptible after 1 day cultivation. AMφ were permissive with a significant increase of their susceptibility after one day cultivation. In a binding assay, it was demonstrated that the attachment of biotinylated PRRSV to AMf is much more efficient than to PMφ and BMo. Two monoclonal antibodies (Mabs) 41D3 and 41D5 which block PRRSV infection of AMφ and are directed against a candidate receptor for PRRSV only reacted with the cell membrane of AMφ. PMA treatment of AMφ blocked PRRSV replication in the cells in a dose-dependent manner. The blocking effect of PMA decreased after 9 h continuous pre-treatment and diminished after 24 h continuous pre-treatment. PMA treatment did not affect the binding of PRRSV and MAb 41D3 and 41D5 to AMφ. Direct or indirect treatment of AMφ and BMo with LPS or cultivation in suspension did not significantly affect their susceptibility. These results provide clear evidence that PRRSV has a strongly restricted tropism for only some sub-populations of porcine monocytes/macrophages and that some specific states of differentiation and activation of monocytes/macrophages considerably affect their susceptibility. |
Twelve hybridomas secreting monoclonal antibodies (MAbs) against Miller virulent strain of transmissible gastroenteritis virus (TGEV) were generated and characterized. In a cell culture immunofluorescence (CCIF) assay, three MAbs directed against peplomer protein (E 2) had perinuclear fluorescence and four unclassified MAbs showed cell membrane fluorescence. Six of these seven MAbs neutralized both attenuated and virulent TGEV, and the seventh (an unclassified MAb) neutralized only the latter virus. Two MAbs able to bind the cell membrane of infected cells had low neutralizing antibody titers (8 to 72) but were able to distinguish between virulent and attenuated TGEV (9- to 72-fold differences in neutralizing titers). Two E 2-specific MAbs had higher neutralizing antibody titers (782 to 34,117) and showed 4- to 13-fold differences in titers against the attenuated and virulent TGEV strains. Five MAbs which were specific for nucleocapsid (N) protein had cytoplasmic, particulate fluorescence in CCIF, and did not neutralize TGEV. Comparison of CCIF antibody titers of MAbs to the virulent and attenuated strains of TGEV indicated that differences existed in titers of most E 2 and all N-specific MAbs, with titers consistently higher against virulent TGEV (homologous strain). Hyperimmune antisera prepared in gnotobiotic pigs against the attenuated, virulent and a recent isolate of TGEV immunoprecipitated the 3 major structural proteins of both the attenuated and virulent TGEV strains. Relative mol. wt. differences in the E 1 and E 2 proteins between the two virus strains were revealed using either the hyperimmune pig sera or MAbs. In addition to the 48 K N protein, a 44 K protein was coimmunoprecipitated by the hyperimmune sera and MAbs, but mainly from lysates of attenuated TGEV. |
The complete nonstructural NS5 gene of Japanese encephalitis virus (JEV) was amplified and cloned into an expression vector. The NS5 protein was expressed in Escherichia coli and purified by His-tag based affinity chromatography. This recombinant NS5 protein exhibited RNA-dependent RNA polymerase (RdRp) activity in vitro in the absence of other viral or cellular factors. The RNA polymerase activity was dependent on divalent cations, and Mn(2+) was found to be 20 times more effective than Mg(2+) in coordinating the catalytic reaction of RdRp, while Ca(2+) inhibited enzyme activity. The optimal reaction conditions for the in vitro RdRp reaction were established. Characterization of the RdRp reaction products demonstrated that the JEV NS5 protein can initiate RNA synthesis through a de novo initiation mechanism in our in vitro reaction system. Comparing the efficiency of different RNA templates, we found that JEV NS5 protein was more efficient in using negative-strand RNA templates, indicating that the JEV NS5 protein is involved in regulating the ratio of positive- to negative-strand RNA. Four amino acid sequence motifs crucial for RdRp activity were also identified using site-directed mutagenesis analysis. All substitutions of the conserved residues within these motifs led to a complete inactivation or severe loss of enzyme activity. |
A persistently-infected neuroblastoma culture [Neuro-2A (JHMV)] was established with the murine hepatitis virus JHM [MHV-JHM]. After 100 days of passage, the endogenous virus [Neuro-2A (JHMV) end] released by this culture was unable to induce the syncytia typical of MHV-JHM and the endogenous virus was not temperature-sensitive. The Neuro-2A (JHMV) culture was cured of virus production by passage under neutralizing antibody [Neuro-2A (JHMV) Ab]. The Neuro-2A (JHMV) and the Neuro-2A (JHMV) Ab cultures were as susceptible to heterologous infection with mengovirus and vesicular stomatitis virus as the uninfected Neuro-2A culture. However, the Neuro-2A (JHMV) and Neuro-2A (JHMV) Ab cultures were partially resistant to homologous superinfection by MHV-JHM and the closely related MHV-A59. Virus related to MHV-JHM was rescued from the antibody-cured cells by cell fusion. The synthesis of MHV-JHM specific antigens by Neuro-2A (JHMV) cells, Neuro-2A (JHMV) Ab cells and 17 Cl-1 cells infected by Neuro-2A (JHMV) end was studied by SDS-PAGE. The genomic RNAs of MHV-JHM and Neuro-2A (JHMV) end were compared by oligonucleotide mapping. The results of the protein and RNA studies indicated that the genome of Neuro-2A (JHMV) end was substantially modified from the genome of MHV-JHM, but the modifications did not significantly alter the molecular size of the viral-specific proteins. |
Treatment of homogenates from Borna disease virus (BDV)-infected brain tissue or cell cultures with Freon-113 yielded infectious particles with a buoyant density of 1.16–1.22 g/ml. Positive- and negative-stranded BDV-specific RNA species as well as three virus-specific proteins, known to be present in BDV-infected cell extracts, were demonstrated in these Freon-treated fractions. When the Freon-purified virus preparations were treated with RNase A prior to RNA extraction, only negative-stranded, genomic RNA was detected in Northern blot hybridizations using sense and antisense RNA probes. These data substantiate that BDV is a negative-stranded RNA virus. |
Experimental infection of 2-day-old gnotobiotic lambs with lamb astrovirus produced mild diarrhoea after an incubation period of about 48 hours. No other clinical symptoms developed. Infection was studied by immunofluorescent and histological examination of tissues from the lambs. Astroviruses infected only mature villus epithelial cells and subepithelial macrophages in the small intestine, where they produced partial villus atrophy. Infected enterocytes were replaced with cuboidal cells from the crypts, and the lesion gradually healed by 5 days after infection. No serological relationship was detected by immunofluorescence between lamb astrovirus antigen in gut sections and antisera to either calf or human astrovirus. |
The pathogenicity for mice of nine strains of mouse hepatitis virus was studied in mice free from the virus by the intracerebral, intraperitoneal, intravenous and intranasal routes of inoculation. |
Various prototype viruses and original specimens were comparatively titrated in cell cultures at 33‡ and 37‡ C. Higher titers at 37‡ were consistently obtained with adenoviruses; for other viruses (enteroviruses, herpesvirus hominis, vaccinia virus, parainfluenza viruses) the titers were mostly identical at either temperature. Original specimens and prototype strains showed the same behavior. The habit to cultivate viruses from throat swabs at 33‡ C is unsatisfactory for adenoviruses. |
Primary rhesus monkey kidney (MK) cells have long been the cells of choice for isolation and propagation of the human paramyxoviruses (parainfluenza 1, 2, 3, 4A, 4B, and mumps). However, problems with the supply and cost of MK cells and the presence of endogenous viruses, including herpes B virus and SV-5, necessitated a search for an alternative cell line. Continuous cell cultures of human origin (L132, A-549, HuT-292, HEK, G-293, G-401, A-498, A-704, CAKI-1, RD) and simian origin (LLC-MK2, BSC-1, MA-104, Vero) were evaluated for their capacity to support the growth of the human paramyxoviruses, as followed by cytopathic effect, hemadsorption, hemagglutination, and EIA. NCI-H292 (HuT-292) human lung mucoepidermoid carcinoma cells (ATCC # CRL-1848) proved to be the most sensitive line for cultivating all serotypes and strains of the paramyxoviruses. These cells were also shown to be a suitable substitute for MK in primary isolation of paramyxoviruses from clinical specimens. RPMI-1640 with 1.5µg/ml trypsin was the preferred maintenance medium; alternatively, Eagle's MEM supplemented with 1.5µg/ml trypsin and 0.1% ITS was satisfactory. NCI-H292 cells are a continuous line with excellent growth characteristics, although the genetic polyploidy of the cells may limit the number of passages of usable cells. |
Egg-grown infectious bronchitis virus, strain Beaudette, was concentrated and centrifuged on sucrose density gradients to separate the virus into five peaks with densities of 1.144, 1.160, 1.172, 1.191 and 1.218 g/cm(3). All peaks retained infectivity, complement fixation activity and were labelled with(3)H-uridine. Morphologically the densest peak consisted of very large virus particles and amorphous material, the other peaks consisted of mainly intact particles although small differences in size and pleomorphism were seen. Polyacrylamide gel electrophoresis of material from the density gradient peaks revealed four major polypeptides and at least 10 minor polypeptides. The proportions of the polypeptides were approximately similar for all peaks with the exception of the densest peak in which the major polypeptides were greatly reduced. The four major polypeptides had approximate molecular weights of 1. 52,000, 2. 45,000, 3. 34,000, 4. 32,000. The major polypeptides 1 and 4 were shown to be glycosylated as were two of the minor polypeptides. |
Isolates from two cases of acute measles, one case of acute measles encephalitis and three patients with subacute sclerosing panencephalitis were compared. This comparison was based upon the electrophoretic analysis of T(1) oligonucleotides from single-stranded, full-length RNA isolated from cytoplasmic nucleocapsids. Although all viruses have oligonucleotides in common, each isolate generated a unique pattern of oligonucleotides. However, no group of oligonucleotides was observed which would allow a differentiation between viruses isolated from acute infections and those isolated from CNS diseases; indicating that probably all measles viruses differ in their nucleotide sequence, regardless of origin. |
Maternally-derived antibody to enterotropic mouse hepatitis virus (MHV) strain Y was transferred to pups by both intrauterine (IgG) and lactogenic (IgA and IgG) routes. Antibody present in the gastric whey of pups suckling immune dams dropped to undetectable levels by weaning age (21 days post partum). MHV-specific IgG was found in the serum of passively immune pups up to 10 weeks of age. Immune dams transferred equal levels of antibody to 3 consecutive litters of pups, without evidence of decline. Immunoblots showed that IgA and IgG in whey and serum were directed against nucleoprotein N and glycoprotein S. MHV-specific IgM was not detected in any sample. |
A remarkable increase in HA titers for weakly haemagglutinating Norwegian arbovirus strains, Uukuniemi and Runde viruses, was achieved by including treatment with the colloidal silica gel Aerosil in the antigen preparation scheme. By combining this procedure with sonication, the titers of sucrose-aceton extracted, infected suckling mouse brains could be increased several hundred times. Good antigens also were obtained from virus grown in BHK 21/c 13 cell cultures and concentrated by polyethylene glycol 6000/NaCl. Rubella virus HA antigen and HB(s)Ag were adsorbed to the gel, and excluded from a preparation by treatment with Aerosil. This indicates a limitation to the universal use of the method, presumably related to the particle size. |
Using six monoclonal antibodies to epitopes a-f on the glycoprotein E2 of Semliki Forest virus (SFV) we found antigenic differences between E2 in infected cells and in virus particles, respectively, if glycosylation was impaired by 2-deoxy-D-glucose or inhibited by N-methyl-1-deoxynojirimycin. Furthermore we concluded that a conformational change of E2 takes place on virus budding. |
In order to differentiate recent isolates of avian infectious bronchitis virus (IBV) in Taiwan, polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and direct sequencing methods were used to type 25 IBV Taiwan isolates. Two conserved sequences that flank the hypervariable region I (HVR I) in the N-terminus of S1 protein gene were chosen as primers. Sequences of 228–231 base pairs (bp) were amplified by PCR from 25 Taiwan isolates and 4 reference strains (H120, Conn, JMK, Holte). PCR products were digested with 5 restriction endonucleases,BsoFI,DdeI,MboII,AluI,RsaI, and different IBV isolates were grouped according to their RFLP patterns. The RFLP patterns of the 4 reference strains in this study matched the published sequences in GenBank. Except 1 vaccine strain, the other 24 Taiwan isolates were different from these 4 and 18 other IBV strains whose sequences were published. The data from PCR-RFLP and sequencing of IBV genomes showed that the 24 Taiwan isolates can be divided into 2 distinct groups, I and II. Seven RFLP patterns are identified in group I and only 1 in group II. |
The cloning and sequencing of anEco RI-Pst I fragment derived from the replicative form of a canine parvovirus (CPV) vaccine strain are reported. The variability of the 5′ end of NS 1 protein gene in the genome is confirmed by comparison with previously determined DNA sequences. A 15 nucleotide deletion was also observed in this vaccine strain. In order to improve CPV diagnosis, radioactively labelled RNA or DNA and biotin labelled DNA obtained by random priming of the recombinant plasmid were used as probes mainly on gut or stool samples from naturally infected dogs. Results of filter hybridization correlated well with histopathological diagnosis of parvovirus infection and with hemagglutination tests performed on dog faeces. We propose that nucleic acid hybridization may be an alternative diagnostic method to ascertain the presence of CPV, especially in frozen samples. |
In Southern India the prevalence of neutralising antibody to Berne virus was high in sera obtained from cattle (49%), horses (38%), and sheep (36%). Neutralising antibody was not detected in sera from humans and monkeys. |
PA-X, a fusion protein belonging to influenza A viruses (IAVs), integrating the N-terminal 191 amino acids of PA gene and the ribosomal frame-shifting product that lengthens out to 41 or 61 amino acids. Since its discovery in 2012, multiple functions have been attributed to this small protein, including a process, where wide-spread protein synthesis in infected host cells is shut down (called host shutoff), and viral replication, polymerase activity, viral-induced cell apoptosis, PA nuclear localization, and virulence are modulated. However, many of its proposed functions may be specific to strain, subtype, host, or cell line. In this review, we start by describing the well-defined global host-shutoff ability of PA-X and the potential mechanisms underlying it. We move on to the role played by PA-X in modulating innate and acquired immune responses in the host. We then systematically discuss the role played by PA-X in modulating the virulence of influenza viruses of different subtypes and host origins, and finish with a general overview of the research advances made in identifying the host cell partners that interact with PA-X. To uncover possible clues about the differential effects of PA-X in modulating viral virulence, we focus on systemically evaluating polymorphisms in PA-X from various viral subtypes and hosts, including avian and human H5N1, H5N6, H9N2, and H7N9 viruses. Finally, we conclude with a proposition regarding the possible future research directions for this important protein. |
Gut contents of nude and normal mice were examined by electron microscopy in association with an outbreak of diarrhea in a colony of nude mice. Virus-like particles with a morphology consistent with previous descriptions of astroviruses of other species were demonstrated in a high percentage of the animals. |
Transmissible gastroenteritis virus was readily adsorbed onto chicken erythrocytes at 4°C. The hemagglutinin thus adsorbed could be eluted from the erythrocytes by incubating in phosphate buffered saline at 37°C. The on chicken erythrocytes for the hemagglutinin was inactivated by neuraminidase and potassium periodate, but not by trypsin, 2-mercaptoethanol and formalin. The hemagglutinin was inactivated by trypsin, papain, pepsin, α-amylase, phospholipase C, neuraminidase, formalin, 2-mercaptoethanol, potassium periodate, ethylether, chloroform, Tween-80 and β-propiolactone, but not by sodium deoxycholate and trichlorotrifluoroethane, suggesting that the active component of the hemagglutinin involved glycoproteins. The hemagglutinin was stable at 37°C or lower temperatures but not at 60°C or higher temperatures. The hemagglutinin activity was resistant to ultraviolet irradiation, while the infectivity was very susceptible. The hemagglutinin and the infectivity were readily sedimented by ultracentrifugation at 45,000 × g for 60 minutes. In rate zonal centrifugation of the hemagglutinin preparation on a sucrose density gradient, the hemagglutinin activity showed a sharp peak at 1.19 g/ml coinciding with the peak of infectivity. The activity in the peak fraction seemed to be structually associated with virus particles. |
We have determined 4380 bases of the sequence from a cDNA clone containing the 3′ end of feline calicivirus strain F9. We find four candidate open reading frames of which three are complete and comprise 245, 317 and 2012 nucleotides. The fourth continues toward the 5′ end. We have expressed the largest complete open reading frame inE. coli. Sera raised to this antigen react specifically with the capsid protein and its intracellular precursor molecule. N-terminal sequence analysis of purified, mature capsid protein confirms this assignment and has identified the position at which precursor is cleaved. |
The Smith strain of mouse cytomegalovirus (MCMV) was infectious for infant and mature DA strain laboratory rats as judged by development of neutralizing antibodies and specific spleen cell proliferation on stimulation with MCMV antigen. An i. p. inoculum of 10(6) PFU of MCMV was fatal for more than two-thirds of infant mice (1–7 days of age), and disseminated viral infection was documented by isolation of virus from body organs. In contrast, weanling and adult rats did not become ill as a result of infection with a larger inoculum of 10(7) PFU. However, these older MCMV infected rats did show transient reversals of T helper/suppressor cell ratios and alterations of immune cell function as detected byin vitro spleen cell proliferation assays. Seven days after MCMV infection, there was a generalized increase in(3)H-thymidine incorporation by spleen cells in both resting (unstimulated) cultures and cultures exposed to mitogens (Con A, PHA, LPS) and to MCMV antigen. At 14 days, the spleen cell proliferation in the unstimulated cultures returned to normal but was depressed compared to controls in response to Con A. These observations show that laboratory rats are susceptible to MCMV infection and that assymptomatic infection may occur and cause transient alterations in lymphocyte subsets and in their reactivity to mitogens. |
Infection of Aedes albopictus cells with Semliki Forest virus (SFV) leads to polykaryocyte formation below pH 6.2. This syncytium formation is accompanied by a decrease of the cellular ATP level. Addition of inhibitors of oxidative phosphorylation leads to a rapid, total depletion of ATP in infected cells at pH 6 and results in an inhibition of polykaryocyte formation. However, when cells were exposed for only a few minutes to pH 6 in the presence of the inhibitors and then kept at pH 7.2, the ATP level partially recovered to values sufficient for syncytium formation. Similar results were obtained after ATP depletion induced by 2-deoxyglucose. Thus, it can be concluded that SFV-induced syncytium formation is an ATP-dependent event. |
Autoreactive T cells specific for myelin basic protein (MBP), a major component of central nervous system (CNS) protein, are frequently found in blood and cerebrospinal fluid of patients with postinfectious encephalomyelitis. This autoimmune syndrome is a CNS complication after infections with a number of different enveloped viruses, e.g. mumps, measles, rubella, influenza and varicella. However, the pathophysiological mechanism leading to this breaking of natural self tolerance in the course of viral infection remains an enigma. A long-lasting hypothesis has suggested that incorporation of cellular (self) proteins into the envelope of budding viruses might be a possible mechanism leading to autosensitization. In a model study we demonstrate here that vesicular stomatitis virus (VS V), grown in myelin protein-expressing cell cultures, is highly efficient in triggering T cell responses to MBP in vitro and can prime autoreactive T cell immune responses in vivo. On the basis of these findings, we suggest that incorporation of CNS membrane components into the viral envelope and subsequent priming of self-reactive immune responses might be the common pathogenic mechanism underlying the postinfectious encephalomyelitis syndrome. |
Recent studies have reported the detection of rabies viral antigens and virions in astrocytes and microglia of rabies-infected animals. As a first step toward understanding whether these glial cells may be involved in rabies virus replication, persistence, and/or pathogenesis, we explored their potential to be infected in vitro. Primary cultures of murine, feline, and human microglia and astrocytes were infected with several different rabies viruses: two unpassaged street virus isolates, a cell culture-adapted strain, and a mouse brain-passaged strain. Infection, as determined by immunofluorescence, was detected in 15 of the 16 (94%) virus-glial cell combinations. Replication of infectious virus, determined by infectivity assay, was detected in 7 of the 8 (88%) virus-cell combinations. These results show that astrocytes and microglia can be infected by rabies viruses, suggesting that they may have a potential role in disease, perhaps contributing to viral spread, persistence and/or neuronal dysfunction. |
The complete genome sequence was determined for avian paramyxovirus (APMV-6) serotype 6 strain teal/Chany/455/2009, isolated from a teal (Anas crecca) in Siberia. Siberia is crossed by four major migration flyways and represents the major breeding area for many wild bird species in the Palearctic. Strain teal/Chany/455/2009 is genetically closely related to Kazakh and Chinese strains and belongs to the genetic group of duck/Hong Kong/18/199/77-like APMV-6 viruses. We show that the virus has low pathogenic potential according to genetic markers and animal model experiments. |
The nucleic acid of infectious bronchitis virus (IBV), like that of other enveloped viruses, consists of discontinuous single stranded RNA. However, unlike many other viruses, there is extreme heterogeneity in the sizes of the RNA fragments, as revealed by centrifugation in sucrose gradients or electrophoresis in polyacrylamide gels. Two principal classes of RNA fragments are present: a. A larger class comprising 74.9–85.4 per cent of total RNA and consisting of fragments having molecular weights ranging from 0.5×10(6) to considerably greater than 3.0×10(6) daltons and, b. A smaller class comprising 9.1–19.7 per cent of total RNA with the size approximately that of ribosomal 4S RNA. All IBV RNA's were fully susceptible to ribonuclease and had a buoyant density in caesium sulphate identical to that of tobacco mosaic virus RNA. No difference in the RNA profile for IBV was observed from the use of different methods of virus purification. The single-stranded RNA's of poliovirus and tobacco mosaic virus remained undegraded after preparation in the presence of IBV. |
Eighteen mouse ascitic fluids containing monoclonal antibodies (MAbs) directed against crystallized hexon of adenovirus (AV) type I were used to map the antigenic structure of the capsomer in reciprocal competitive binding ELISA. With the help of peroxidase-labelled MAbs at least nine epitopes (epitope clusters) located on three distinct antigenic sites were identified on the hexon. Epitope on antigenic site I recognized by two MAbs could be the genus specific antigenic determinant based on the broad reactivity patterns of the MAbs. Epitopes on the antigenic site II recognized by fifteen MAbs could be divided into seven epitope clusters according to the competition patterns. Antigenic site III recognized by one MAb completely differs from the antigenic site I and on the basis of one-way blocking with all the MAbs specific for antigenic site II, should be also different from the latter one. The data suggest that the seven epitope clusters of antigenic site II contain partially overlapping epitopes and may be a part of a large single immunodominant antigenic region on AV1 hexon as well as on hexons of heterologous types. |
Sialodacryoadenitis virus of rat readily propagated and induced marked cytopathic effect in a rat cell line, LBC cell culture, which provides a sensitive, practical assay system for viral infectivity and neutralizing antibody, and a satisfactory source of the virus. |
Two primers with the length of 22 bases each and 400 bases apart on the spike protein gene of avian infectious bronchitis virus (IBV) were prepared. Using these primers, the genome RNA from twelve strains of the various serotypes were reverse-transcribed to cDNA and amplified by polymerase chain reaction (PCR). With all strains, 400 base DNA was amplified, indicating that there were no apparent insertions or deletions in this region. However, the amplified DNA showed different cleavage patterns by the restriction enzymes. These 12 strains were classified into 5 groups. The strain typing based on a comparison of the cleavage patterns was consistent with the previous serological typing. This study thus provides a simple and rapid method for typing of IBV. |
Subgenomic mRNA from a virulent isolate of porcine transmissible gastroenteritis virus (TGEV) was used to produce cDNA clones covering the genome region from the 3′ end of the pelomer gene to the start of the integral membrane protein gene. The nucleotide sequence of this area was determined using clone pTG11 and a previously reported cDNA clone pTG22. Three open reading frames (ORFs) were identified encoding putative polypeptides of relative molecular masses (M(r)) 6,600, 27,600, and 9,200. The sequence encoding the M(r) 9,200 polypeptide was found to be present on the “unique” 5′ region of the 3.0 kb mRNA species whereas the other two ORFs mapped on the 3.9 kb mRNA species. Differences between the ORFs from this strain of TGEV and those from a previously reported avirulent strain of TGEV were compared. |
The growth, stability and seroprevalence in laboratory rodents of the two known strains of mouse adenovirus were compared. The FL strain of mouse adenovirus grew in both L 929 murine fibroblasts and in CMT-93 murine rectal carcinoma cells, whereas the K 87 strain grew only in CMT-93 cells. The bulk of the FL progeny virus was released from the host cells. K 87 virus was largely cell-associated. Both virus strains were stable at 37° C in liquid medium. The K 87 strain was completely inactivated after 5–15 minutes at 56° C, whereas FL infectivity was still detected after two hours at this temperature. Both virus strains were stable in the dessicated state for 14 days, although FL viability was more dependent on the presence of protein in the virus diluent. Seroepidemiologic data suggest that viruses antigenically related to mouse adenovirus are more prevalent among laboratory rats than among laboratory mice and that the virus(es) infecting rats differ from those infecting mice. Results of retrospective serologic testing suggest an association between mouse adenovirus and an outbreak of disease in a mouse breeding colony. |
Two day-old athymic (rnu/rnu) and euthymic (rnu/+) rat pups nursing immune or non-immune dams were inoculated oronasally with the Yale strain of rat virus (RV-Y). All athymic and euthymic pups (57/57) from immune dams remained clinically normal, whereas 51 of 66 athymic and euthymic pups from non-immune dams died within 30 days. Infectious RV was detected by explant culture in 12 of 15 surviving pups of both genotypes from non-immune dams 30 days after inoculation, but in none of the 57 surviving pups from immune dams. RV-Y DNA was detected by Southern blotting in kidneys of surviving athymic pups from non-immune dams but was not detected in pups from immune dams. Euthymic pups from immune dams appeared not to produce endogenous antibody to RV after virus challenge, whereas euthymic pups from non-immune dams produced high-titered RV immune serum. Pups of both genotypes given immune serum prior to or with RV were fully protected from disease and persistent infection, whereas pups given immune serum 24 hours after RV were partially protected. These studies show that RV antibody offers significant protection against lethal and persistent RV infection. |
Growth of fastidious adenovirus serotype 40 (Ad 40) in several cell lines was investigated. Ad 40 was able to readily propagate in human intestinal cell line, HRT 18. Coinfection assays were made in non-permissive and permissive cells between Ad 40 and Ad 5dl 312 or dl 1520, mutants deleted in E 1 A and E 1 B regions, respectively, to test the ability of Ad 40 to complement these mutants and vice versa. Ad 40 could enhance Ad 5dl 312 DNA synthesis in HRT 18 and HeLa cells, although its own DNA disappeared in the presence of this mutant in HRT 18 cells. In coinfection with dl 1520, Ad 40 DNA synthesis was inhibitied by dl 1520 in HRT 18 cells and dl 1520 DNA synthesis was inhibited by Ad 40 in 293 cells. This might reflect the presence of unusual products encoded by Ad 40 E 1 B region. |
Previous studies have shown that replication in vitro of the porcine parvovirus (PPV) isolate, KBSH, was restricted at 39°C but not at 37°C. In contrast, replication of the Kresse isolate was restricted at 37°C but not at 39°C. In this study, Kresse and KBSH isolates were passaged up to ten times in swine testicle (ST) cells at non-permissive temperatures, and at subsequent passage viral protein synthesis, viral DNA synthesis, and progeny virus were evaluated. KBSH became adapted for replication at 39°C upon serial passages, displaying an appreciable increase in viral progeny, viral polypeptides, and viral DNA concentration. This finding was also observed with Kresse virus isolate continuously passaged at 37°C. Neither isolate became adapted for replication at 32°C. In an attempt to examine the effect of in vitro passage at non-permissive temperatures on pathogenicity in swine, KBSH passaged 10 times either at 37°C or 39°C was inoculated into swine fetuses. Two of four fetuses inoculated with 39°C-passaged KBSH were dead and hemorrhagic or mummified. All four fetuses inoculated with 39°C-KBSH contained viral antigen and viral DNA. In contrast, fetuses inoculated with 37°C-passaged KBSH, or with cell culture fluid were normal in appearance. Viral antigen and viral DNA were not demonstrated in fetuses inoculated with 37°C-KBSH or cell culture fluids. These findings suggest the possibility that the ability to replicate at 39°C is associated with virulence in swine fetuses. |
The sequence of the MHV-A 59 non-structural gene 4 (ns 4) reveals two open reading frames. The upstream ORF potentially encodes a 19 amino acid (2.2 kDa) polypeptide and the downstream ORF potentially encodes a 106 amino acid (11.7 kDa) polypeptide. This is in contrast to MHV-JHM gene 4 which expresses a 15 kDa protein. Cell free translation of a synthetic mRNA containing both ORFs of MHV-A 59 ns 4 results in the synthesis of a 2.2 kDa poylpeptide; the predicted 11.7 kDa product of the MHV-A 59 downstream ORF is not detected during cell free translation nor in infected cells. These results add to the recent data suggesting that expression of some of the ns proteins of MHV is not necessary for efficient growth in tissue culture. |
Five prototype strains of mouse hepatitis virus (MHV) -1,-3, -S,- A59 and -JHM were analyzed for their ability to induce interferon (IFN) in seven cell lines of rodent origin. Induction of IFN by all of the prototype MHV strains was infrequent and unpredictable, while IFN was produced consistently by five cell lines treated with known inducers. Priming and/or aging of cells did not enhance IFN induction by the MHV strains except in the case of MHV-A59 which consistently induced moderate levels of IFN on L-cells which were both primed and aged. Kinetic studies of MHV-A59-induced IFN on primed and aged L-cells demonstrated that detectable levels of IFN were not produced until 24 hours post-inoculation (p.i.). Peak levels were attained at 30 hours p.i. with no additional IFN produced through 48 hours p.i. MHV-induced IFN was similar in composition and properties to Newcastle disease virus-induced IFN. The sensitivities of the five MHV strains to eight concentrations of preformed L-cell IFN were also assessed. All strains except MHV-S fit a linear model with MHV-3, MHV-A59 and MHV-JHM having similar slopes. At most concentrations MHV-3 was less sensitive than MHV-1, -A59 or -JHM to IFN. The response curve for MHV-S was non-linear. This strain was more sensitive to the antiviral effects of the pre-formed IFN except at the highest concentrations of IFN used. |
The cDNA sequence of the 3′-terminal genomic region of the Québec IAF-exp91 strain of porcine reproductive and respiratory syndrome virus (PRRSV) was determined and compared to those of other reference strains from Europe (Lelystad virus) and US (ATCC VR2385, MN-1b). The sequence (2834 nucleotides) which encompassed ORFs 3 to 7 revealed extensive genomic variations between the Québec strain and Lelystad virus (LV), resulting from high number of base substitutions, additions and deletions. The ORFs 5, 3, and 7 seemed to be relatively the most variable; the predicted encoding products of the Québec and LV strains displayed only 52%, 54%, and 59% amino acid identities, respectively. Nevertheless, in vitro translation experiments of the structural genes (ORFs 5, 6, and 7) and radio-immunoprecipitation assays with extracellular virions gave results similar to those previously reported for LV. In contrast, close genomic relationships were demonstrated between Québec and US strains. Taking together, these results indicate that, although structurally similar, North American PRRSV strains belong to a genotype distinct from that of the LV, thus supporting previous findings that allowed to divide PRRSV isolates into two antigenic subgroups (U.S. and European). |
The p19 matrix (MA) protein of human T-cell leukemia virus type I (HTLV-I) was exposed on the surface of MOLT-4#8 cells in the very early step of the virus infection. Transfer of the virus-binding MOLT-4#8 cells from 4°C to 37°C resulted in increased detection of the viral gp46 and p19 MA protein on the cells, which was, however, inhibited by 4°C or cytochalasin B treatment. These data showed that increased temperature and fluidity of the cell membrane were required for the increased detection of gp46 and p19 after viral adsorption. On the other hand, exposure of the p19 MA protein was not observed on the virus-treated U937 cells although gp46 was detected. This was not due to inefficient binding of the HTLV-I to the U937 cells, since the methanol-fixed cells were p19 MA protein-positive. MOLT-4#8 cells induced marked cell fusion when co-cultured with MT-2 cells, but U937 cells induced no fusion. All of these results indicated that these two cell lines differed in the property of plasma membrane in terms of degradation of HTLV-I envelope after viral adsorption. Uncoating of the HTLV-I might occur on the plasma membrane, especially on MOLT-4#8 cells. |
Plaque assay in DBT cells with DEAE-dextran and trypsin presents a titration system for MHV3 as sensitive as the LD(50) assay in mice. |
The predicted amino acid sequence and secondary structures of S1 of the spike protein (S) of infectious bronchitis viral (IBV) strains from Europe, the U.S.A., and Japan were compared. An antigenic determinant that was highly conserved in both the primary amino acid sequence and secondary structure of all strains was identified between amino acid positions 240 to 255. A synthesized peptide corresponding to this region was found to react with all polyclonal antisera examined from various IBV strains and with one monoclonal antibody (MAb), 9B1B6, out of nine known to react with the S of Gray. The specificity of the interaction with MAb 9B1B6 was confirmed by competitive ELISA using bound and unbound peptide. Interestingly, the previously described epitope for 9B1B6 had been characterized as cross-reactive with several strains of IBV, as conformation-independent but reacting only with intact whole S, and as associated with the functional integrity of other epitopes, including neutralizing epitopes on the S protein. The apparent critical functional and structural nature of this highly immunogenic determinant suggests a potential contribution in developing protective, cross-reactive subunit vaccines to IBV. |
Organ cultures of mouse trachea were infected with some indigenous mouse viruses. Mengovirus and reovirus type 3 grew to high titer; inocula of, respectively, 10(2) and 10(3) TCID(50) were required to initiate infection. Organ cultures supported also the growth of mouse hepatitis viruses, MHV-3 and MHV-S, though to a lesser extent. Viral production was noted for periods of as long as two weeks. None of the viruses had a noticeable effect on the ciliary activity or acquired such capacity on serial passage in organ cultures. |
Ten strains of avian infectious bronchitis virus (IBV) were titrated as plaqueforming units in primary chick embryo fibroblast cells. In the absence of trypsin, plaques were only formed by Beaudette-42 and Iowa-609 strains. When trypsin was incorporated in the overlay medium of cell monolayers, all the IBV strains tested produced plaques within 4 days after inoculation. Incorporation of 20–40 µg of trypsin per ml of the overlay medium seemed to be suitable for plaque formation of IBV. A preliminary investigation was made of the mode of action of trypsin. |
Canine rotavirus particles were visualized by direct electron microscopy in the feces from a clinically normal dog. The virus was subsequently propagated in cell cultures; it was chracterized and compared with rotaviruses from other species. Replication of the virus in cell culture was found to be less dependent upon trypsin than that of human, bovine and porcine rotaviruses. Reproducible, sharp-edged plaques of various sizes were produced by the canine rotavirus in an established cell line of fetal rhesus monkey kidney, MA104, under overlays of carboxymethyl cellulose or agarose. Intracytoplasmic inclusion bodies of different sizes and shapes were produced in infected MA104 cells. By plaque reduction neutralization assay, a two-way antigenic relationship was found between the canine (CU-1) and simian (rhesus MMU 18006 and SA-11) rotaviruses. The canine rotavirus had a one-way antigenic relationship with feline (Taka), bovine (NCDV), and porcine (OSU) rotaviruses. |
Suckling CD1 mice infected intracerebrally or extraneurally with OC43 virus developed a lethal neurotropic infection with high titres of virus in the brain. Examination of infected brain by routine H & E staining revealed no necrosis even in extensively infected tissue. Resistance to infection developed with increasing age, and by 20 days of age mice were completely insusceptible to i. c. inoculation. Virus replication was also demonstrable by FA staining, in spinal cord, dorsal root ganglia and retina. All other tissues were insusceptible and in particular, macrophages from both susceptible and resistant mice were found to be resistant to infection bothin vivo andin vitro. Immunosuppression rendered 15 day old mice more susceptible to infection but adult mice remained insusceptible. The transfer of immune or non immune spleen cells from resistant mice did not confer resistance to newborn mice. Treatment of resistant mice with anti interferon globulin (AIG) did not render them more susceptible. These results indicate that the immune response is partially responsible for the development of resistance to OC43 infection but that it is only partially protective and other factors must also be required. The basis for the unique susceptibility of neural tissues in suckling mice is being investigated. |
Viral and bacterial antigen and antibody assays were prospectively applied to study the microbial actiology of community-acquired pneumonia in 195 hospitalised children during a surveillance period of 12 months. A viral infection alone was indicated in 37 (19%), a bacterial infection alone in 30 (15%) and a mixed viral-bacterial infection in 32 (16%) patients. Thus, 46% of the 69 patients with viral infection and 52% of the 62 patients with bacterial infection had a mixed viral and bacterial aetiology. Respiratory syncytial virus (RSV) was identified in 52 patients andStreptococcus pneumoniae in 41 patients. The next common agents in order were non-classifiedHaemophilus influenzae (17 cases), adenoviruses (10 cases) andChlamydia species (8 cases). The diagnosis of an RSV infection was based on detecting viral antigen in nasopharyngeal secretions in 79% of the cases. Pneumococcal infections were in most cases identified by antibody assays; in 39% they were indicated by demonstrating pneumococcal antigen in acute phase serum. An alveolar infiltrate was present in 53 (27%) and an interstitial infiltrate in 108 (55%) of the 195 patients. The remaining 34 patients had probable pneumonia. C-reactive protein (CRP), erythrocyte sedimentation rate and total white blood cell count were elevated in 25%, 40% and 36% of the patients, respectively, CRP was more often elevated in patients with bacterial infection alone than in those with viral or mixed viral-bacterial infections. No other correlation was seen between the radiological or laboratory findings and serologically identified viral, bacterial or mixed viralbacterial infections. By using a comprehensive serological panel, the causative agent could be found in over 50% of patients with pneumonia. We conclude that RSV and pneumococcus are the two most common organisms causing pneumonia in children. Our results suggest that mixed viral-bacterial aetiology is common in lower respiratory tract infections affecting children. |
Two recently recognized viruses obtained from a dog with glossitis and from mink with hemorrhagic pneumonia were characterized by electron microscopy. The results of the negative-stained preparations indicated that the viruses were structurally compatible with the calicivirus group. |
Seven fragments of the spike (S) gene cDNA of transmissible gastroenteritis virus (TGEV), as well as the full length cDNA, were cloned and expressed in baculovirus vectors. Piglets were immunized with cells infected with the recombinant viruses. Each of the recombinants induced TGEV-specific antibodies detected in a fixed cell enzyme immunoassay. The amino terminal half of the S protein, containing all four major antigenic sites (A, B, C and D), and encoded by a 2.2 kb fragment of the S gene, induced virus neutralizing (VN) antibody titers comparable with those induced by the complete S protein. Recombinant proteins lacking the A antigenic site, or with a deletion including the putative receptor binding sites and the D antigenic site, were not capable of inducing levels of VN antibodies similar to those induced by the whole S protein. |
A polymerase chain reaction (PCR) based assay capable of detecting and differentiating seven strains of equine arteritis virus (EAV) from around the world was developed. The primers for the PCR were chosen from the ORF 6 gene encoding the unglycosylated membrane protein (M). Viral RNA from cell culture fluids infected with each of the seven EAV strains and RNA from the live vaccine, Arvac, was detected by PCR using four sets of primers. The sensitivity of detection was increased from 100 to 1000 times by performing nested PCR enabling the detection of RNA at a level of 0.5–5 PFU. Differentiation among the virus strains and the live vaccine was achieved by cutting the PCR-amplified products from three sets of primers with six restriction endonucleases. Using this procedure it was possible to distinguish among the seven EAV strains used. |
We report a naturally occurring human astrovirus (HAstV) strain detected in two different geographic locations. We identified two isolates of this strain in a diarrhea outbreak at a child care center in Houston, Texas; and two isolates in diarrhea stool samples from two children in Mexico City. All four isolates were detected in stool samples by enzyme immunoassay (EIA). One of the Mexican isolates was typed by EIA and all four isolates were HAstV-5 by typing RT-PCR. The four isolates were >97% nucleotide-identical in two different genomic regions: ORF1a (246nt), and the 3′ end of the genome (471nt). One isolate from each geographic location was further sequenced in the transition region from ORF1b to ORF2 (1255nt) and this region of the two isolates showed ≥ 99% nt identity. Phylogenetic analyses of sequences of eight HAstV antigenic types and the novel strain in the transition region demonstrated the new strain being closely related to HAstV-3 in ORF1b, but closest to HAstV-5 in ORF2. These results and high sequence identity among all HAstV antigenic types in the transition region and RNA structural predictions supported a potential recombination site at the ORF1b/ORF2 junction. This is the first evidence that recombination occurs among human astroviruses. |
Fifteen isolates of Infectious bronchitis virus (IBV) were obtained from the kidney, trachea, and cecal tonsil of IB suspected chickens between 2001 and 2002 years in Korea. The S1 glycoprotein gene of IBV isolates were amplified by reverse transcriptase – polymerase chain reaction (RT-PCR) and analyzed by restriction fragment length polymorphism (RFLP) analysis. Fifteen Korean IBV isolates were classified into 4 groups by their RFLP patterns using restriction enzymes, HaeIII, BstYI, and XcmI. The RFLP patterns for 3, 1, and 1 of 15 isolates corresponded to the patterns of IBV Arkansas, Connecticut, and Massachusetts strains, respectively. Ten of 15 isolates generated unique KM91 RFLP pattern that was observed in the IBV KM 91 strain previously isolated in Korea. To confirm genetic diversity in the S1 genes of IBV isolates, viral RNAs of representative 9 of 15 IBV isolates were amplified, cloned, sequenced and compared with published sequences for non-Korean IBV strains. Korean IBV isolates showed amino acid sequence similarity between 61.8% (K446-01 and K161-02) and 96.1% (K281-01 and K210-02) with each other and they showed amino acid sequence similarity between 42.9% (K161-02 and GA980470) and 96.5% (K203-02 and KB8523) compared to non-Korean IBV strains. By phylogenetic tree analysis, Korean IBV field isolates were branched into five clusters in which 3 clusters were differentiated from non-Korean IBV strains. Especially, Korean IBV isolates K069-01, K507-01, K774-01 and K142-02 formed a separate cluster. It seems that IBVs continue to evolve and IBVs showing various genetic differences may cocirculate in Korea. |
We have used Western blotting to examine the accumulation of feline calicivirus proteins within the infected cell. Experiments using elevated growth temperature to block post-translational cleavage have demonstrated two additional high molecular weight protein bands 125 kd and 123 kd respectively which may be precursor polyproteins. Inhibition of proteolytic processing withp-fluorophenylalanine led to the accumulation of several additional protein species which may represent intermediates in the protein processing pathway. None of these proteins were related to the 62 kd major capsid protein (cP 62) of the virus as judged by reaction with monoclonal antibodies. The production of a 76 kd capsid precursor protein (cpP 76) was demonstrated for the first time in FCV-infected cells. The pathway by which calicivirus polypeptides are made thus appears highly complex and may involve temporal regulation of protein synthesis as well as protein processing. Tentative identification of primary, intermediate and mature forms of virus proteins is discussed. |
Localization of neutralizing, serotype specific epitopes of infectious bronchitis virus has been difficult because these epitopes are conformationally dependent. We identified amino acids involved in a serotype specific, conformationally dependent epitope by analysis of the S1 gene of 13 monoclonal antibody-neutralization-resistant mutants. Substitutions in the predicted amino acid sequence of these mutants were located at residues 304 and/or 386. Most of the substitutions at residue 304 were from threonine to isoleucine, whereas the substitutions at residue 386 were from arginine to proline, histidine, cysteine, or tryptophan. Based on this data, it appears that AA residues at 304 and 386 on the S1 glycoprotein are involved in a virus neutralizing serotype specific epitope. |
To investigate the molecular mediators of poliovirus tissue tropism, the correlation between poliovirus replication and poliovirus receptor expression was examined in a primary human tissue system. Earlier work [M. Freistadt, H. Fleit, and E. Wimmer, Virology 195: 798–803 (1993)] showed that the cellular receptor for poliovirus is present in 87% of primary human monocytes and that peripheral blood mononuclear cells support poliovirus replication. In the current work, monocytes, obtained by adherence or by a novel negative selection procedure using specific monoclonal antibodies to lymphocyte surface antigens, supported poliovirus replication. However, total virus yield was low and infectious centers assays revealed that a minority (6%) of monocytes become productively infected. Viral yield from monocytes was lower than from the heterogeneous mononuclear cells; however, when uninfected lymphocytes were added back to infected monocytes, the higher viral yield was restored. The purity of the cells did not significantly affect the number of cells infected. These results suggest that more poliovirus is produced per cell from activated rather than unactivated monocytes. Furthermore, poliovirus replication in monocytes may reflect genuine in vivo replication and comprise a system in which to determine molecular mediators of poliovirus tissue tropism. |
The complete nucleotide sequence of Pelargonium line pattern virus (PLPV) has been determined. The PLPV genomic RNA comprises 3884 nt and contains six open reading frames (ORFs) potentially encoding proteins of 27 (p27), 13 (p13), 87 (p87), 7 (p7), 6 (p6), and 37 kDa (p37), respectively. The arrangement of these ORFs on the PLPV genome closely resembles that of members of the genus Carmovirus in the family Tombusviridae and, moreover, most of the putative PLPV gene products showed high identity with proteins of this viral group. However, several striking differences were noticed. Carmoviruses generate two subgenomic RNAs whereas PLPV produces a single one. In addition, only p7 showed similarity with movement proteins of carmoviruses whereas p6 (as p13) has no viral (or other) homologs. This protein might be expressed from a non-canonical start codon or, alternatively, through a −1 frameshift (FS) mechanism. Both, the production of one subgenomic RNA and the likely involvement of a −1 FS for expression of an internal ORF parallel the translation strategies reported for the unique species of the genus Panicovirus, belonging also to the family Tombusviridae. Overall, the results support the placement of PLPV in this family although its peculiar characteristics preclude its direct assignment to any of the current genera. |
Analysis of the nucleic acid of infectious bronchitis virus by SDS polyacrylamide gel electrophoresis revealed an RNA of molecular weight 9.0×10(6) Daltons. The RNA was shown to have a sedimentation coefficient of 50. |
Necrotising enterocolitis (NEC) is one of the most serious gastrointestinal diseases among newborns and it mainly affects those in intensive care units. The aetiology of the disease has been reported to be multifactorial and both sporadic cases and nosocomial outbreaks have occurred. In this report, we review 17 epidemics of NEC reported in the literature between 1973 and 1999. The number of confirmed cases ranged from 1 to 32 with an average of 10.5 confirmed cases. On average, 16.15% of cases required surgery (range 0–66.6%). The average mortality rate was 6.25% (range 0–87.5%). The mean age at disease onset was 9.5 days (range 6.6–29 days). Most of the infants had low birth weight (median weight 1,395 g; range 1,112–2,788 g, calculated on the reported mean weights). The main risk factors associated with NEC were: low birth weight, low gestational age, low Apgar score, perinatal complications, hyaline membrane disease, and umbilical catheterisation. The bacteria involved often included Enterobacteriaceae, particularly Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae type 3305573. The causative role of Clostridia in NEC is controversial. With regard to viral agents, coronarovirus, rotavirus and enterovirus, such as echovirus type 22, were isolated during some of the epidemics. The recommended control measures for NEC epidemics are those used for epidemics of other orofaecally transmitted infections. Conclusion Understanding the epidemiology of necrotising enterocolitis is fundamental if adequate preventive control measures are to be developed and applied. |
To investigate the role of Hantaan virus envelope glycoprotein in infection, a panel of monoclonal antibodies (MAbs) was examined in vitro with several serological tests and in vivo by passive transfer experiments in mice. An antigenic site, specific for the inhibition of infected cell focus was detected with the focus inhibition neutralization test (FINT), in addition to the neutralization related antigenic sites, which were revealed by the ordinary focus reduction neutralization test (FRNT). Suckling mice were given the MAbs by passive transfer followed by lethal Hantaan virus challenge. All neutralizing MAbs detected by either FRNT or FINT protected all mice from lethal infection, confirming the importance of the antigenic sites as a protective antigen. Mice given non-neutralizing MAbs by passive transfer, however, began to die earlier than the control group; mean time to death (18.2±2.1 to 21.5±2.8 days) being significantly shorter than that of the control group (25.8±1.8, p<0.01, Mann-Whitney,U probability test). Virus titers in brains of mice which died early, were about 10 times higher than those of control mice. These results indicated the early death phenomenon of mice which was mediated by the antivirus antibody. |
Several systems are available for the expression of foreign gene sequences inEscherichia coli. We describe the use of prokaryotic expression products of viral gene fragments in order to identify the regions that specify the binding sites of antibodies. This approach is particulary successful if the antigenicity does not depend on the native protein, but only on the amino acid sequence, i.e., if the epitope is sequential. Combining prokaryotic expression with the use of synthetic peptides often permits a fast and accurate mapping of an epitope. The occurrence of immunodominant sequential epitopes on the surface of viruses seems to be a widespread phenomenon. |
High-flow nasal cannula (HFNC) is a widely used ventilatory support in children with bronchiolitis in the intensive care setting. No data is available on HFNC use in the general pediatric ward. The aim of this study was to evaluate the feasibility of HFNC oxygen therapy in infants hospitalized in a pediatric ward for moderate–severe bronchiolitis and to assess the changes in ventilatory parameters before and after starting HFNC support. This prospective observational pilot study was carried out during the bronchiolitis season 2011–2012 in a pediatric tertiary care academic center in Italy. Interruptions of HFNC therapy and possible side effects or escalation to other forms of respiratory support were recorded. Oxygen saturation (SpO(2)), end-tidal carbon dioxide (ETCO(2)), and respiratory rate (RR), measured for a baseline period of 1 h before and at specific time intervals in 48 h after the start of HFNC were recorded. Twenty-seven infants were included (median age 1.3 months; absolute range 0.3–8.5). No adverse events, no premature HFNC therapy termination, and no escalation to other forms of respiratory support were recorded. Median SpO(2) significantly increased by 1–2 points after changing from standard oxygen to HFNC (p <0.001). Median ETCO(2) and RR rapidly decreased by 6–8 mmHg and 13–20 breaths per minute, respectively, in the first 3 h of HFNC therapy (p <0.001) and remained steady thereafter. Conclusions: Use of HFNC for oxygen administration is feasible for infants with moderate–severe bronchiolitis in a general pediatric ward. In these children, HFNC therapy improves oxygen saturation levels and seems to be associated with a decrease in both ETCO(2) and RR. |
Previous virological and immunological studies have suggested that multiple sclerosis (MS) is an auto-immune disease triggered by a virus infection. In order to inhibit the growth of measles virus in the patient's jejunum, we obtained an IgA-rich cow colostrum containing anti-measles lactoglobulin resistant to proteases. This colostrum was orally administered to patients with MS to investigate its effect on the course of the disease. Measles-positive antibody colostrum was orally administered every morning to 15 patients with MS at a daily dosage of 100 ml for 30 days. Similarly, measles-negative antibody (< 8) control colostrum was orally administered to 5 patients. As a clinical assessment, disability scores developed by the International Federation of Multiple Sclerosis Societies were used. As a result, of 7 high NT titre (512–5120) anti-measles colostrum recipients 5 patients improved and 2 remained unchanged. Among 8 low NT titre (8–32) anti-measles colostrum recipients 5 patients improved and 3 remained unchanged. However, of 5 negative NT titre (< 8) colostrum recipients 2 patients remained unchanged and 3 worsened. No side-effects were observed in colostrum recipients. These findings suggest the efficacy of orally administered anti-measles colostrum in improving the condition of MS patients (P < 0.05). |
Coxsackievirus B 5 (CB 5) labeled with tritiated uridine was used to trace the interaction of the virus with explant cultures of porcine ileum. Similarly labeled human poliovirus 1 (PO 1), which is not specifically retained by porcine tissue, was used as a control. The explant procedure employed could maintain ileal tissue in a differentiated state for up to 48 hours. Porcine ileum was acquired from both young (4–6 week-old) and adult (9–11 month-old) animals. Inoculated explants of either absorptive or lymphoid tissue were incubated at temperatures selected to permit either viral adsorption or penetration and elution to occur. Retention of radioactive virus was quantitated by liquid scintillation counting and localized by autoradiography. Only in absorptive tissue explants from young animals did adsorption of CB 5 at 6°C exceed penetration at 37°C. This suggested that incubation at 6°C may not be an appropriate condition for studying enterovirus adsorption in explants. CB 5 penetrated most efficiently into lymphoid tissue explants from young animals, indicating that these tissues could discriminate between CB 5 and PO 1. In explants from adults, CB 5 penetrated equally well into lymphoid and absorptive tissues. Virus penetrated into the absorptive epithelial cells and, possibly, the lamina propria near the villous tips. Low efficiency of penetration, and the non-critical function of these target cells, may help account for the characteristic lack of gastrointestinal symptoms in enterovirus infections. |
Enhancement of feline infectious peritonitis virus (FIPV) infection of feline macrophages was studied using monoclonal antibodies (MAbs) to the FIPV strain 79-1146. Adherent cells recovered from the feline lung and peritoneal cavity phagocytosed fixed red blood cells, and formed Fc-mediated rosettes. Enhancement of virus infection by MAb was investigated by inoculating alveolar macrophages with a mixtures of viral suspension and MAb, and examining the cells for intracellular viral antigen by the immunofluorescence assay and the amount of infectious virus in the supernatant fluid after incubation. The replication of FIPV in macrophages was enhanced by non-neutralizing MAbs recognizing peplomer protein (S) and transmembrane protein (M) of the virus. Even among the MAbs having the ability to neutralize FIPV strain 79-1146, some reversely enhanced virus infection when they were diluted. The enhancement was suppressed by pretreatment of the MAb with protein A. The enhancement was reduced by the use of F(ab′)(2) fragment of MAb. These results demonstrated antibody-dependent enhancement (ADE) of FIPV infection in macrophage. The replication of FIPV 79-1146 strain in macrophages from FIPV antibody-positive cats was more enhanced than in those from antibody-negative cats. |
Twenty-four volunteers at the Common Cold Unit were divided into two groups of twelve. One group was vaccinated orally with an enterovirus (LEV 4) and the other with nutrient broth. Both groups were challenged three days later with intranasal rhinovirus 4 and they were observed clinically and monitored by laboratory tests to see if any modification of the rhinovirus infection occurred. All the vaccinated volunteers were successfully infected with LEV 4 and were excreting the enterovirus in the faeces at near maximum titres at the time of the rhinovirus infection, following which 67 per cent of the volunteers were infected and 29 per cent developed symptoms. However, the vaccinated group did not differ from the unvaccinated in respect of the illness induced, the excretion of rhinovirus type 4 or the rise of RV 4 antibody titre. LEV 4 was isolated from the nasopharynx of some of the volunteers, but the rhinovirus infection was not modified even in these. Interferon was present in the serum and nasal washings of nine volunteers in all, of whom only 3 had received the LEV 4 vaccination. Two additional volunteers were shown to be insusceptible to reinfection with LEV4. It was concluded that live enterovirus vaccination does not induce viral interference. |
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