the viral envelope with the endosomal membrane. Thus, the capsid reaches the cytosol, decays and releases the genome The (+)ssRNA (positive, single-stranded RNA) at first only acts as a template for the translation of the non-structural proteins, which are synthesized as a large polyprotein and are then cut into single proteins. The sequences for the structural proteins are first replicated by the viral RNA polymerase (Replicase) via a complementary (-)ssRNA as a template and translated as a separate short mRNA. This short subgenomic RNA is additionally packed in a virion. Translation of the structural proteins produces a large polypeptide (110 Dalton). This is then endoproteolytically cut into E1, E2 and the capsid protein. E1 and E2 are type I transmembrane proteins which are transported into the endoplasmatic reticulum (ER) with the help of an N-terminal signal sequence. From the ER the heterodimeric E1·E2-complex reaches the Golgi apparatus, where the budding of new virions occurs (unlike alpha viruses, where budding occurs at the plasma membrane. The capsid proteins on the other hand stay in the cytoplasm and interact with the genomic RNA, together forming the capsid. Transmission RuV is transmitted via respiration between humans. Epidemiology On the basis of differences in the sequence of the E1 protein, two genotypes have been described which differ by 8 - 10%. These have been subdivided into 13 recognised genotypes - 1a, 1B, 1C, 1D, 1E, 1F, 1G, 1h, 1i, 1j, 2A, 2B and 2C. For typing, the WHO recommends a minimum window that includes nucleotides 8731 to 9469. Genotypes 1a, 1E, 1F, 2A and 2B have been isolated in China. Genotype 1j has only been isolated from Japan and the Philippines. Genotype 1E is found in Africa, the Americas, Asia and Europe. Genotype 1G has been isolated in Belarus, Cote d'Ivoire and Uganda. Genotype 1C is endemic only in Central and South America. Genotype 2B has been isolated in South Africa. Genotype 2C has been isolated in Russia. Literature David M. Knipe, Peter M. Howley et al. (eds.): Fields Virology 4. Auflage, Philadelphia 2001 C.M. Fauquet, M.A. Mayo et al.: Eighth Report of the International Committee on Taxonomy of Viruses, London San Diego 2005 References External links Viralzone: Rubivirus Rubella Togaviruses