Hepatitis B virus DNA polymerase gene polymorphism based prediction of genotypes in chronic HBV patients from Western India

BACKGROUND Hepatitis B Virus (HBV) infection is one of the major causes of liver cirrhosis, hepatocellular carcinoma and deaths due to the acute or chronic consequences worldwide. HBV is distributed into various genotypes based on nucleic acid sequence variation. OBJECTIVES To develop a method of HBV genotyping and drug resistance interpretation using partial sequencing of polymerase gene. METHODS This study was performed on 98 HBV infected patients' serum samples from Western India. A nested PCR protocol was designed for amplification of pol gene from HBV genome and Sanger's sequencing of the gene fragment. Sequences were aligned with HBV reference sequences for phylogenetic analysis and for characterization of genetic diversity. Drug resistance mutations were screened using HBVSeq program from Stanford University. RESULTS Distribution of HBV genotypes showed predominance of genotype D, circulating in 76 (77.55%) patients (p < 0.05). Genotypes A and C were less prevalent and were identified in 4 (4.08%) and 18 (18.37%) patients, respectively. Anti-retroviral drug resistance mutations were not detected in any patient. CONCLUSION A method for determination of HBV genotypes using pol gene sequencing which simultaneously detects major drug resistance mutations has been established. HBV genetic diversity may play an important role in treatment decision.