H. Doi et al., HEPATITIS-C VIRUS (HCV) SUBTYPE PREVALENCE IN CHIANG-MAI, THAILAND, AND IDENTIFICATION OF NOVEL SUBTYPES OF HCV MAJOR TYPE-6, Journal of clinical microbiology, 34(3), 1996, pp. 569-574
Subtype analysis of hepatitis C viruses (HCVs) obtained from patients
with chronic liver disease in Chiang Mai, Thailand, was performed, Of
46 HCV isolates, 13 (28%) were shown to belong to HCV subtype 3a (HCV-
3a), 10 (22%) to belong to HCV-1a, 7 (15%) to belong to HCV-1b, 1 (2%)
to belong to HCV-3b, and 1 (2%) to belong to a variant group, as dete
rmined from partial nucleotide sequences of the NS5B region of the vir
al genome. Analysis of 5' untranslated region sequences identified fiv
e other isolates (11%) of HCV type 1 and two other isolates (4%) of ty
pe 3, Detailed phylogenetic positions for the variant described above
and those previously obtained from blood donors and drug addicts in Ch
iang Mai were determined by a six-parameter neighbor-joining method on
the basis of core, E1, and NS5B region sequences. The results reveale
d that those sequence variants represent novel subtypes of HCV type 6.
The HCV type 6 isolates appear to be antigenically different from iso
lates of HCV types 1 and 2, as determined by a serotyping method that
utilizes recombinant peptides corresponding to a portion of the NS4 pr
otein. The significance of subtype analysis around this area is discus
sed.