ANALYSIS OF HEPATITIS-C VIRUS ISOLATES AMONG HEALTHY BLOOD-DONORS ANDDRUG-ADDICTS IN CHIANG-MAI, THAILAND

Hepatitis C virus (HCV) isolates obtained from 25 anti-HCV antibody-po sitive healthy blood donors and 29 drug addicts in Chiang Mai, Thailan d, were analyzed. HCV RNA was detected in 23 blood donor samples (92%) and 24 drug addict blood samples (83%) by PCR for a portion of the NS 5 region. Subtype analysis revealed that HCV type 3a (HCV-3a) was the prevailing subtype (30%), which was followed in prevalence by HCV-1a ( 21%), -1b (13%), -3b (13%), and -6a (2%). Six (13%) of the 47 isolates showed low sequence similarities with known types and subtypes. The s equence variants could be grouped into four branches in a molecular ev olutionary phylogenetic tree.