Hepatitis B Virus Genotypes in Latvia

Abstract

The aim of this study was to investigate the properties of HBV genomes isolated from patients with acute and chronic hepatitis, liver cirrhosis, and hepatic coma admitted to the Infectology Center of Latvia. HBV genotypes and HBsAg subtypes were determined by direct S-gene sequencing. Genotypes D (72.17%) and A (27.96%) were predominant. Only one case (0.87%) of HBV genotype E was found. Prevalence of genotype D over genotype A was more strongly pronounced in isolates from patients with acute hepatitis than from patients with chronic hepatitis- 74%- 24% and 68%-32%, respectively. Number of previously described and some new mutations (Ser21Thr in preC region, Tyr134Lys, Phe134Leu, Ile110Met, Thr118Ile and Ser136Tyr in S-gene) were discovered by direct sequencing of PCR fragments corresponding to preS/S and preC/C regions and to a fragment of the X gene of HBV genome. The most frequently mutations were found in the region of the basal core promoter, preC and major immunodominant region of core protein and domain a of S protein. In general the rate of mutations discovered in chronic patients was just 1,23 times higher then in patients with acute hepatitis, at the same time the ratio for the hot-spot preC 1896 stop mutation was higher and reached 1,81. A possible role of discovered mutations in the HBV pathogenesis is discussed. The findings are relevant to diagnosis and prognosis of HBV-induced liver disease.