Abstract B82: First report of genotype F and novel mutations in the core promoter region of HBV isolates from a northern Indian population

Abstract

Abstract B82 Hepatitis B virus (HBV) isolates (35) from North India having different stages of hepatitis were studied for genotypes distribution, core promoter mutations and phylogenetic origin. Assays of SGOT, SGPT and HBeAg were performed in all samples using commercial available kits. Genotypes were determined in all the studied subjects by restriction fragment length polymorphism and core promoter mutations by direct sequencing of PCR products. HBV genotype D was found in 57% of the isolates while 40 % isolates have genotype A and 3% have genotype F. This is the first report of genotype F in Indian population. Earlier it was reported from population from Japan, USA, Argenita and Venezuela. Subgenotype D 1 was predominant among genotype D isolates followed by genotype D2 and D6. Subgenotype A1 was predominant among genotype A followed by A3. Genotype F has subgenotype F2. 1762A -T and 1764G-A mutations were observed in 50% isolates having active viral replication of HBV virus. These are also present in the sera of HCC patients. Wild types were observed in many asymptomatic patients. Novel mutations like 1697G 1698C1727A 1740T were observed in the 50% isolates having nearly normal or slightly high ALT/AST level and all the samples were positive for HBeAg. 1811C 1812C1813T mutations were observed in 15% isolates with slightly high ALT/AST level. 1858T was observed in genotype D with HBeAg positive. 1898A stop codon mutations responsible for HBeAg negativity as observed in Japanese, South African and other world populations could not be observed in the isolates under study. Phylogenetic tree of HBV isolates based on the precore/core gene sequences was drawn with HBV sequences from other parts of the world and previously reported Indian strains from eastern part. Majority of strains shows a high degree of closeness with Chinese and eastern Indian strains. Two rare sequences having nearly 46% and 26% difference in the nucleotide sequence with the available wild type with respect to the CP region were also observed. Efforts are going on to amplify the genotype F to full length. The studies regarding mutations, their role in disease progression and potential as biomarkers of hepatitis B is actively underway. Citation Information: Cancer Prev Res 2008;1(7 Suppl):B82.