GENETIC-HETEROGENEITY OF HEPATITIS-G VIRUS ISOLATES FROM DIFFERENT PARTS OF THE WORLD

Comparative sequence analysis of a 354 nt fragment of the NS5 region o f hepatitis G virus (HGV) isolates was performed to assess two levels of HGV genomic variability: (1) heterogeneity of HGV within an infecte d individual, and (2) heterogeneity of different HGV isolates. Compari son of nucleotide sequences of DNA clones from two virus isolates demo nstrated that in each infected individual HGV is represented by a popu lation of virions with closely related but heterogeneous genomes (quas ispecies). Phylogenetic analysis of nucleotide sequences of 42 isolate s collected from 14 countries revealed less significant genome variabi lity of HGV as compared to hepatitis C virus. Sequences of all HGV iso lates fell into one group of distribution of evolutionary distances. O n a phylogenetic tree all HGV sequences segregated into numerous branc hes. All sequences of isolates from Africa, South and South-East Asia, however, were clustered together and were separated from those of oth er isolates collected in Europe, North America and Central Asia.