patients receiving chronic hemodialysis ( chd ) are at a high risk of infectious complications . prior to developing screening system and vaccines for hepatitis b virus ( hbv ) , the most common etiologic agent of hepatitis in chronic hemodialysis patients was hbv . afterwards , hepatitis c virus ( hcv ) was a main problem in chd ( 1 ) . from 1995 to 1996 , two independent laboratories in the usa isolated a new enveloped rna virus similar to flaviviruses . the first laboratory named it gb virus c / gbv - c and the second as hepatitis g virus ( hgv ) ( 2 ) . hgv is a virus in the flaviviridae family and known to be infectious for human , but it has not been established to cause human disease with certainly ( 3 ) . however , there is a suspicious link between hgv infection and acute or fulminant hepatitis , chronic hepatitis and hepatic fibrosis ( 4 , 5 ) . until now , five major genotypes of hgv are known as genotype 1 is the most common in the west africa , genotype 2 known in the us and europe , genotype 3 in parts of asia , genotype 4 is specific for myanmar , vietnam and indonesia and finally genotype 5 is frequently observed in south africa ( 6 , 7 ) . high prevalence is observed among subjects with risk of parenteral exposure including those with exposure to blood and blood products , such as chd patients and intravenous drug users ( 8) . chd patients and other kinds of chronic renal failure ( crf ) patients usually require blood transfusion . it is one of main risk factors of hgv transmission ( 9 - 11 ) . some studies suggested links between hgv and transfusion requirement , dialysis duration , renal transplantation and other kinds of viral hepatitis in chd patients ( 10 - 12 ) . approximately , 2% of healthy united states blood donors had viremia with hgv and up to 13% of blood donors had antibodies against e2 protein , indicating a possible prior infection ( 13 ) . sexual contact and vertical transmission could be another route of hgv transmission . furthermore , hcv and hiv-1 ( human immunodeficiency virus-1 ) infected patients have evidence of higher rate of hgv infection ( 14 , 15 ) . recently , several studies revealed that hgv could decrease progression of hiv virus and prolong the duration between hiv infection and aids ( 16 ) . increased chronic disorders such as diabetes ( dm ) , renal failure and end stage renal disease ( esrd ) have become important issues in health care policies . however , none of the studies indicated that hgv infection can cause any liver enzyme elevation or hepatic failure certainly , but coinfection with other hepatitis viremia can increase morbidity and mortality rates ( 17 ) . different surveys indicated prevalence of hgv in chd patients between 3.1% in japan and 57.5% in france ( 10 , 11 ) . therefore , estimating hgv infection in dialysis patients of different countries seems to be reasonable and applicable in health care system to design standard prevention and treatment plans . the aim of the present study was to determine the prevalence and risk factors of hgv in iranian esrd patients undergoing routine chd . this was a descriptive cross - sectional and multicentric study conducted in four major centers of hemodialysis in iranian army hospitals in tehran , iran from february 2012 to march 2013 . this survey covered 138 patients of 4 dialysis units , 81 males and 57 females , respectively . west , north , city center and east as well as southeast of tehran were covered by units of 1 , 2 , 3 , and 4 , respectively . in these hospitals , all dialysis patients are examined for detection of hiv-1 , hbv and hcv every six months , and patients with positive blood samples referred to one specific unit of hemodialysis . therefore , all known cases of other types of hepatitis and hiv-1 were referred to one specific hospital based on routine hospitals regulations . the following epidemiological data were obtained in all patients ; ( i ) history of previous blood transfusion , ( ii ) length of time on dialysis , ( iii ) history of major surgery , ( iv ) blood group , ( v ) household contact with hepatitis , ( vi ) family history of hepatitis , ( vii ) reasons of dialysis ( dm , hypertension , infection , renal stone , polycystic kidney and others ) , ( viii ) age and ( ix ) gender . prior to initiation , the survey was approved by aja medical university ethics committee and an informed consent was obtained from all patients . two milliliters of blood was sampled from every patient and centrifuged immediately , then plasma was separated stored at -20c and transferred to laboratory . immediately , hgv - rna was extracted from 100 l plasma samples using the guanidine isothiocyanate - phenolchloroform method and reverse transcribed using random primer and the moloney murine leukemia virus ( mmlv ) reverse transcriptase ( fermentas , lithuanian ) . the oligonucleotide primers for amplification of c - dna by pcr detected hgv rna based on highly conserved domains of the 5 non - coding regions . the nucleotide sequences of the primers were 5-cactataggtgggtcttaag-3 ( 150 - 169 nt and 5- gcctattggtcaagagagac-3 ( 352 - 333 nt ) for the first round of pcr and 5- gcgcacggtccacaggtgtt-3 ( 207 - 226 nt ) and 5 gggcgacgtggaccgtacgt-3 ( 326 - 307 nt ) for the second round of pcr . pcr amplification was performed for 30 cycles ( 94c for 30 seconds ; 55c for 90 seconds ; 72c for 90 seconds ) in the first round of pcr and 35 cycles with the same time temperature conditions in the second round of pcr . amplified products were separated with agarose gel ( 2% ) electrophoresis and visualized by ethidium bromide staining under uv - detector system . the limit of detection was 1000 copy / ml using the samples with determined hgv viral load ( determined with a homemade kit based on rna in vitro transcription ) . this was a descriptive cross - sectional and multicentric study conducted in four major centers of hemodialysis in iranian army hospitals in tehran , iran from february 2012 to march 2013 . this survey covered 138 patients of 4 dialysis units , 81 males and 57 females , respectively . west , north , city center and east as well as southeast of tehran were covered by units of 1 , 2 , 3 , and 4 , respectively . in these hospitals , all dialysis patients are examined for detection of hiv-1 , hbv and hcv every six months , and patients with positive blood samples referred to one specific unit of hemodialysis . therefore , all known cases of other types of hepatitis and hiv-1 were referred to one specific hospital based on routine hospitals regulations . the following epidemiological data were obtained in all patients ; ( i ) history of previous blood transfusion , ( ii ) length of time on dialysis , ( iii ) history of major surgery , ( iv ) blood group , ( v ) household contact with hepatitis , ( vi ) family history of hepatitis , ( vii ) reasons of dialysis ( dm , hypertension , infection , renal stone , polycystic kidney and others ) , ( viii ) age and ( ix ) gender . prior to initiation , the survey was approved by aja medical university ethics committee and an informed consent was obtained from all patients . two milliliters of blood was sampled from every patient and centrifuged immediately , then plasma was separated stored at -20c and transferred to laboratory . immediately , hgv - rna was extracted from 100 l plasma samples using the guanidine isothiocyanate - phenolchloroform method and reverse transcribed using random primer and the moloney murine leukemia virus ( mmlv ) reverse transcriptase ( fermentas , lithuanian ) . the oligonucleotide primers for amplification of c - dna by pcr detected hgv rna based on highly conserved domains of the 5 non - coding regions . the nucleotide sequences of the primers were 5-cactataggtgggtcttaag-3 ( 150 - 169 nt and 5- gcctattggtcaagagagac-3 ( 352 - 333 nt ) for the first round of pcr and 5- gcgcacggtccacaggtgtt-3 ( 207 - 226 nt ) and 5 gggcgacgtggaccgtacgt-3 ( 326 - 307 nt ) for the second round of pcr . pcr amplification was performed for 30 cycles ( 94c for 30 seconds ; 55c for 90 seconds ; 72c for 90 seconds ) in the first round of pcr and 35 cycles with the same time temperature conditions in the second round of pcr . amplified products were separated with agarose gel ( 2% ) electrophoresis and visualized by ethidium bromide staining under uv - detector system . the limit of detection was 1000 copy / ml using the samples with determined hgv viral load ( determined with a homemade kit based on rna in vitro transcription ) . the study population consisted of 81 males ( 59% ) and 57 females ( 41% ) . moreover , the mean dialysis onset of patients was 24.75  30.82 months and the mean weekly dialysis duration was 10.78  18.25 hours . only 2.5% of all patients had a positive family history of hepatitis diseases . in six of 138 patients , hgv was detected by nested rt - pcr and hgv rna positive and shown 120 bp bands length in 1.2% agarose gel electrophoresis . therefore , an overall prevalence of 4.3% was found for hgv among hemodialysis patients in our study . there was a significant difference between the two genders ( hgv positive and hgv negative ) ( p = 0.045 ) . furthermore , duration of dialysis in a week , had a substantial difference between hgv positive and hgv negative patients ( p < 0.001 ) , indicating that increasing dialysis duration could increase the risk of hgv infection in patients ( tables 1 and 2 ) . additionally , there was noother association between hgv and age , blood transfusion , major surgery , dialysis onset , dm and blood groups ( tables 1 , 2 and 3 ) . the secondary information of this study revealed the prevalence of cause of hemodialysis in tehran ( table 4 ) . here , we investigated the prevalence and risk factors of hgv infection in hemodialysis patients in tehran army hospitals . the results indicated a prevalence of 4.30% in those hemodialysis patients who all had negative results for hbv , hcv and hiv . as patients of the present study refer to hospitals three days a week , the risk of nosocomial transmission is increasing . several reports showed a high prevalence of hgv viremia ( 1 - 4% ) in europe and north american healthy population and widespread prevalence ( 10 - 33% ) among south american as well as african people ( 3 , 4 , 8 , 9 ) . a high rate ( 55% ) several studies showed that it would not cause major liver damage , whereas some others showed it might infect and replicate in hepatocytes ( 15 , 17 , 19 ) . there is a polish report comparable to our study evaluating hgv among dialysis patients with negative results for anti hcv antibody . in their survey , prevalence of hgv was 6.7% among 215 patients ( 19 ) . in a study in turkey , iran s neighboring country , prevalence of hgv was 14% among hemodialysis patients and 2% in blood donors ( 20 ) . in an iranian investigation , 3.89% of hemodialysis patients had positive results for anti e2 antibody , but none of their samples had positive results for hgv rna ( 17 ) . ramos filho et al . in brazil found that 14.6% ( 95% ci : 9.2 - 21.7 ) of samples had positive results hgv rna . a high positivity for hgv rna was observed in patients who received kidney transplant ( 16.7% ) followed by those on hemodialysis ( 15.3% ) and peritoneal dialysis ( 7.7% ) ( 15 ) . however , none of these studies showed any significant difference in demographic factors , but our study showed substantial difference between gender and duration of dialysis in a week and hgv positivity . there are some concerns in our study , which could cause misunderstanding of real prevalence of hgv . for instance , initially , hiv , hcv and hbv in our study had negative results , because patients with positive blood samples for hiv , hcv and hbv viruses referred to one specific unit of hemodialysis , based on routine hospitals regulations . secondly , a significant difference between gender and hgv positivity in the present study could be due to low percentage of hgv positive patients . here , we used rt - pcr technique for detecting hgv with an acceptable sensitivity ( 21 - 24 ) . the limit of detection was 1000 copy / ml using samples with determined hgv viral load ( determined with a home - made kit based on rna in vitro transcription ) . four hospital centers were included in this investigation , so this could be considered a multicenter study . in conclusion , patients on maintenance hemodialysis treatment are at high risk of acquiring parenterally transmitted viral infections . this study evaluated the prevalence of hgv among esrd and under hemodialysis patients in iranian army hospitals in tehran . the current results showed that 4.30% of hemodialysis patients in these hospitals had positive results for hgv rna . duration of dialysis in a week is important to increase the risk of hgv transmission . further studies are needed to elucidate real prevalence , risk factors and characteristics of hgv infection in iranian hemodialysis patients .
background : gb virus c ( gbv - c ) or hepatitis g virus ( hgv ) is a newly discovered and enveloped rna positive - stranded flavivirus - like particle , which has not yet been proven to have major negative effects on liver.objectives:increasing the risk of blood - borne infections in hemodialysis patients is a main health care concern in different countries . 
 therefore , it is important to estimate the prevalence and risk factors of hepatitis g virus infection in iranian hemodialysis patients to design standard prevention and treatment plans.patients and methods : in this multicenter observational or epidemiologic study , 138 patients who underwent hemodialysis in iranian army hospitals in tehran were included . 
 serum hiv antibody ( ab ) , hcv antibody and hbs antigen ( ag ) were assessed . 
 demographic data such as gender , age , blood group , cause of renal failure , dialysis onset and duration were collected from medical files . 
 gbv - c / hgv was evaluated by nested reverse transcription polymerase chain reaction ( rt - pcr ) method . 
 then , all data were analyzed by spss ver . 
 13.results:in total , 81 males and 57 females were included . 
 the mean age of patients was 62.16  14.86 years . 
 six ( 4.3% ) had positive results for gbv - c / hgv by rt - pcr . 
 except gender ( p = 0.045 ) and duration of dialysis in a week ( p < 0.001 ) , other demographic factors revealed no significant difference ( p > 0.05 ) . 
 all patients had negative results for hiv ab , hcv ab and hbs ag.conclusions:overall , 4.3% of patients had positive results for gbv - c / hgv and all negative for hiv , hcv and hbv . 
 further studies are needed to elucidate real prevalence , risk factors and characteristics of hgv infection in iranian hemodialysis patients .