A study on genotypes of hepatitis B virus among hemodialysis patients in Khuzestan province

Introduction and objective: Hepatitis B virus (HBV) is a member of Hepadnaviridae and a major causative agent of chronic and acute hepatitis, liver cirrhosis and hepatocellular carcinoma. Genotype determination of HBV is based on PCR-RFLP and sequencing of genome of the virus. The genotype formation is mainly due to mutations of HBV precore, S, and YMDD (tyrosine-methionine-aspartate-aspartate motif in the C domain of the HBV DNA polymerase gene) genome area. Moreover, some of the mutant HBV remains undetectable by serological tests (occult hepatitis). Since the genotypes of HBV and occult hepatitis B has not been studied in our area, this study was conducted to determine both occult hepatitis B infection and genotypes among hemodialysis patients.

Materials and methods: Two hundred and fifty hemodialysis patients were selected in this study. The sera of the patients were collected and the extracted DNA was used as template of PCR to amplify a 479bp fragment of the viral genome. The PCR products were digested by Ava2 and Mbo1 restriction enzymes. Based on RFLP patterns, the genotypes were determined. The HBV markers including; HBV surface antigen (HBsAg), hepatitis Bc antibody (HBcIgG), hepatitis B virus e antigen (HBeAg) and hepatitis B virus e antibody (HBeAb) were carried out for all the patients by ELISA test.

Results: Fifty (20%) out of 250 sera showed positive HBV by PCR. Out of the 50 positive cases for HBV, 46(92%) belonged to genotype D2 and 2(4%) cases of them were B6 genotype. Ten cases were positive for HBV by PCR test but negative by ELISA test (4% occult hepatitis).

Conclusion: Prevalence of HBV infection was high among the dialysis patients (20%), and occult hepatitis B was 4% in these patients. The dominant genotype of HBV was D2 (92%) followed by genotypes B6 (4%) in hemodialysis patients.