High frequency of drug resistance mutations in the HBV genome in ART-experienced HIV-coinfected patients in southwestern Nigeria.

Background: HBV and HIV infections are highly endemic in sub-Saharan Africa and Nigeria while HBV-HIV coinfection is not uncommon. Antiretroviral (ART)-treatment for HIV can affect HBV whereby antiviral resistance mutations in the HBV genome can be selected. Here, we determined the prevalence of resistance mutations among ART-experienced and ART-naive HIV-HBV-coinfected patients in southwestern Nigeria. Methods: A total of 81 serum samples from HBV-HIV-coinfected patients who were either ART-naive or received lamivudine (3TC)-containing ART-therapy and HBV-monoinfected patients were analysed. Hepatitis B surface antigen (HBsAg) was detected using ELISA. HBV-positive samples were confirmed by PCR amplification of the surface and polymerase regions. Mutations conferring drug resistance to HBV were analysed by direct sequencing. Phylogenetic analysis was performed to identify the HBV genotype. Results: Of the 81 HBsAg-positive samples, 27 had detectable HBV DNA by real-time PCR with mean viral loads of 6.77 log IU/ml. Phylogenetic analyses showed a predominance of HBV genotype E. A high prevalence (22.2%; 6/2 7) of HBV resistance mutations among ART-experienced HBV-HIV-coinfected patients was detected. However, a relatively high selection rate of resistance mutations in drug-naive HIV-HBV-coinfected (3.7%; 1/27) and in HBV-monoin-fected patients, potential drug resistance mutations (7.4 0 10; 2/27) were also observed. HBV polymerase amino acid substitutions found included rtV173L, rtL180M, rtM204V, rtK212R, rtS213T, rtV214A, rtL229V and rtP237A/S. Conclusions: Drug resistant mutations were detected frequently in ART-experienced HIV-HBV patients. Well-coordinated antiviral therapy for HIV patients coinfected with HBV should include proper HBV diagnosis and resistance testing to minimize the emergence and spread of antiviral drug resistance.