Prevalence and molecular characterization of Hepatitis B in HIV infected individuals in Botswana

Abstract

Background: Hepatitis B Virus (HBV) is a major coinfection in HIV infected patients and it has emerged as an important cause of morbidity and mortality in this group since the start of HAART. HIV/HBV coinfection prevalence varies geographically even within the same country. In Botswana the coinfection prevalence data is very sparse and what is reported varies. Ten HBV genotypes and several sub genotypes have been described differing by geographic distribution, course of disease, response to treatment and development of mutations. Even though data have shown that genotypes are predictive of disease outcome, the circulating HBV genotypes in Botswana remain unknown. This study therefore aims at determining the HIV/HBV coinfection prevalence rate and the circulating HBV genotypes in Botswana. Methods: This is a retrospective cross sectional study of HIV adults initiating HAART. The study was conducted at Botswana Harvard Partnership laboratory. Hepatitis B surface antigen (HBsAg) was screened for in 300 baseline samples and those which were positive were also screened for HBeAg. A 415 base pairs fragment of the polymerase gene was amplified by semi-nested polymerase chain reaction (PCR) for the HbsAg positive. The PCR product was genotyped using Big Dye sequencing chemistry and the sequences were analysed for genotypes,subgenotypes and mutations using Stanford HBV Drug resistance and geno2pheno databases. Results: Of the 300 participants, 28(9.3%) were HBsAg positive and 5(17.9%) were HBeAg positive. Of the 27 samples that were successfully genotyped, genotype A was found in 23 (85.2%), 22 subgenotype A1 and 1 subgenotype A2, genotype D subgenotype D3 made up the remaining 4(14.8%). Known escape mutations were found in 12(44.4%) with the most common one being 131N found in 8(29.6%) of the participants. The other escape mutations were R122K, T123A, Q129R, G130N, M133T and F134V. No drug resistance mutations were detected. Conclusions: The HIV/HBV prevalence is consistent with what has been reported in the country. The predominant genotype in this cohort is A1 and its consistent with findings from the region. Escape mutations previously associated with failure of HBsAg detection and vaccine or immunoglobulin therapy were found in a significant number of participants. No known drug resistance mutations were found in the cohort.