Difference of HBV genotype distribution between acute hepatitis and chronic hepatitis in Japan

Background: Recently genotype A which is rare in the patients in chronic hepatitis B (CHB) was frequently noted in patients with acute hepatitis B (AHB). To investigate their clinical and virological features, we studied the AHB patients in the past 5 years. Patients and Methods: 98 patients with AHB and 80 patients with CHB admitted to our hospital between 1998 and 2003 were studied. Results: Genotype A was not found in CHB but was frequently noted in AHB (p < 0.001). Comparison of the clinical features of acute hepatitis between the two major genotypes, A and C, homosexual and heterosexual with multiple partners were frequently seen among genotype A patients (p < 0.001). On the other hand, infection from steady partner showed a tendency to be more frequent in genotype C (p = 0.065). In genotype A, the levels of HBV-DNA on admission was higher (p = 0.007) and AHB has significantly more frequently progress to chronic infection than in genotype C (p = 0.028). Phylogenetic analysis of genotype A revealed that almost all strains from homosexual men belonged not to the African type A1 but to the Western type A2. Conclusions: Genotype A has increased recently among AHB in Japan. This fact may correlate to promiscuous intercourse in high risk group. Prophylactic efforts should be considered to prevent the prevailing of genotype A.