It has been reported that hepatitis B virus (HBV) mutants carrying mutations in the pre-S region can be found in infected patients. In this study, we investigated the prevalence of the HBV variant with the pre-S mutant in different geographic regions, including countries with low and high levels of endemic HBV infection, and analyzed the correlation with clinical findings. We examined 387 HBV DNA-positive serum samples from individuals among 12 countries, consisting of Vietnam, Myanmar, Thailand, China, Korea, Nepal, Japan, Russia, Spain, United States, Bolivia, and Ghana. HBV pre-S mutants were detected in 71 (18.3%) of 387 serum samples tested. This mutant was the most prevalent in Vietnam (36%), followed by Nepal (27.3%), Myanmar (23.3%), China (22.4%), Korea (14.3%), Thailand (10.5%), Japan (7.7%), and Ghana (4.3%). In contrast, no case with this mutation was found in Russia, Spain, United States, and Bolivia. Among the HBV deletion mutations, 15.5% (11 of 71) occurred in the pre-S1 and 46.5% (33 of 71) in the pre-S2 regions. Eight (11.3%) cases had a mutation in both the pre-S1 and pre-S2 regions. In addition, a point mutation at the pre-S2 starting codon was observed in 19 (26.7%) cases. The detection rate of the HBV mutant in patients with hepatocellular carcinoma was significantly higher than in other patients (P < 0.05). Furthermore, these mutants were found more frequently in genotype B (25%) and genotype C (24.5%) than in the other genotypes (P < 0.05). Our results indicated that there was a high prevalence of HBV pre-S mutation in regions of endemic HBV infection in Asia. Furthermore, the pre-S mutation appeared to be correlated with hepatocellular carcinoma and HBV genotypes.Hepatitis B virus (HBV) is a small, enveloped 3.2-kb DNA virus with four open reading frames (ORFs). HBV envelope proteins are encoded by three overlapping envelope genes contained within a single ORF: pre-S1, pre-S2, and S. Depending on the translated initiation site among S, pre-S2, or pre-S1, three different-size proteins are produced: a small hepatitis B surface protein (small HBs), containing 226 amino acid residues; a middle hepatitis B surface protein (middle HBs), containing 55 additional amino acid residues; and a large hepatitis B surface protein (large HBs), containing 108 or 119 additional amino acid residues, depending on the serotype. The pre-S region has been proved to mediate hepatocyte attachment of the virus (amino acids 21 to 47 in pre-S1) (1,20,21,26), to contain B-cell and T-cell epitopes (5, 16, 17) and a binding site for neutralizing anti pre-S2 antibody (amino acids 120 to 145) (1,20,26); and an S promoter for controlling the production of middle HBs and small HBs. Naturally occurring HBV with the pre-S mutation has been reported in patients with chronic infections, fulminant hepatitis (32), post-lamivudine treatment (14), and post-liver transplantation (29). It is known that the rate of occurrence has varied in the literature (4, 7-9, 27, 31). However, the clinical significance of this mutation is still ...

A genomic characterization of hepatitis B virus (HBV) was done for 56 pre-S1/pre-S2 genes and 10 full-length HBV genotype C isolates from five Asian countries. Phylogenetic analysis of the pre-S1/pre-S2 genes revealed two major groups within genotype C: one for isolates from southeast Asia including Vietnam, Myanmar and Thailand (named HBV/C1) and the other for isolates from Far East Asia including Japan, Korea and China (named HBV/C2). This finding was confirmed by phylogenetic analysis based on the full-length sequence of 32 HBV genotype C isolates, including 22 from database entries. Two isolates from Okinawa, the island off the southern end of Japan, formed a different branch. Specific amino acid sequence changes were identified in the large S protein (amino acids 51, 54, 60, 62 and 73) and P protein (amino acids 231, 233, 236, 248, 252 and 304). Our results indicate that genotype C of HBV can be classified into at least two subgroups. INTRODUCTIONHepatitis B virus (HBV) infection is a global health problem, with more than 350 million people chronically infected worldwide (Lee, 1997). The infection is associated with a wide spectrum of clinical symptoms, ranging from acute or fulminant hepatitis to various forms of chronic liver disease, such as chronic hepatitis, cirrhosis and hepatocellular carcinoma. HBV has been classified into genotypes A-G, with an intergenotypic diversity of at least 8 % in the full genome sequence (Okamoto et al., 1988;Norder et al., 1994). HBV genotypes have a distinct geographical distribution and correlate with severity of liver disease (KiddLjunggren et al., 2002). Genotypes B and C are prevalent in Asia, and genotype C causes more serious liver disease than genotype B (Shiina et al., 1991;Orito et al., 2001). Moreover, HBV strains in the same genotype may differ in their capacity to induce clinical liver disease. Subgroup Ba of genotype B, which is recombinant with genotype C, is found predominantly in southeast Asian countries and appears to have more detrimental effects than subgroup Bj (Sugauchi et al., 2002a). Recently, a novel genotype C variant has been found in Australian aborigines (Sugauchi et al., 2001). Therefore, it is possible that virological differences in HBV genotype C exist in Asian countries resulting in different clinical outcomes for patients. To analyse this further, we carried out genomic characterization of HBV genotype C isolates and found that they could be classified into at least two subgroups. METHODSSource of sera, genotyping and serotyping of HBV. HBV DNA-positive sera were obtained from 56 patients in five different Asian countries: 17 from Vietnam, 21 from Myanmar, four from Thailand, nine from China and five from Japan (three from Tokyo and two from Okinawa). All sera were found to be HBV genotype C by PCR genotyping using type-specific primers as reported previously (Naito et al., 2001). The HBV serotype was inferred from the The DDBJ/GenBank/EMBL accession nos. of sequences reported in this study are HBV-VT101, AB112063; HBV-VT103, AB111946; ...

An unenveloped single-stranded DNA virus (TTV) has been reported in association with posttransfusion and acute and chronic hepatitis of unknown etiology. DNA of TTV was tested for by polymerase chain reaction with heminested primers in 127 patients with chronic liver disease and 105 healthy blood donors in Thailand. TTV DNA was detected in 23 (59%) of the 39 patients without hepatitis B surface antigen or RNA of hepatitis C virus, at a frequency significantly higher than the detection in 21 (36%) of the 59 patients with HBsAg (P < 0.05) or in 38 (36%) of the 105 blood donors (P< 0.05). Among patients with chronic liver disease, TTV DNA occurred in those with liver cirrhosis and hepatocellular carcinoma more frequently than in those with chronic hepatitis (35 of 65 or 54% vs. 20 of 62 or 32%, P< 0.05). There were no differences in age, sex, or markers of infection with hepatitis B, C and GBV-C/HGV viruses, indicating a mode of transmission of TTV different from those of the other hepatitis viruses. Phylogenetic analysis indicated three different genotypes of TTV with six distinct subtypes in Thailand. Based on these results, TTV would have a role in the development of chronic liver disease of unknown etiology in Thailand.