IDENTIFICATION, PREVALENCE AND ASPECTS OF MOLECULAR-BIOLOGY OF HEPATITIS-G VIRUS

Hepatitis G virus (HGV) is a newly identified member of the Flavivirid ae family, The positive-sense RNA genome of the virus contains a singl e open reading frame that encodes the viral polyprotein, Its genomic o rganization is similar to that of the hepatitis C virus (HCV) with whi ch it has only 25% homology at the nucleotide level, Nucleotide sequen ces from the NS-3 helicase region of HCV varied by 10-30%, HGV is ther efore much less variable than HCV, Construction of phylogenetic trees, and calculation of mean distances between possible subtypes, indicate d one level of variation in NS-3 sequences: the degree of variation be tween isolates was similar to that observed between HCV subtypes, Thus no evidence for clustering of sequences into multiple genotypes was f ound, The virus is transmissible through blood transfusion and by expo sure to blood products or intravenous drug use, and may result in acut e or chronic hepatitis, A causative role of HGV in acute and chronic h epatitis is not yet established, Concurrent infection with hepatitis B virus (HBV) and HCV is common and persistent viraemia has been docume nted for many years, in many cases, in the absence of transaminase ele vations.