Diversity of HBV genotypes and their association with precore/basal core mutations among HBsAg-positive patients in Ibadan, Nigeria

<b>Background.</b> Hepatitis B virus (HBV) is the most implicated cause of severe liver disease and hepatocellular carcinoma worldwide. Studies have shown that the basal core protein (BCP) and precore protein (PC) of HBV play a significant role in HBV-related carcinogenesis. There is a paucity of data on the type and effect of BCP and PC mutations in Nigeria. This study aims to genotype HBV and investigate any mutations within the BCP and PC among HBV patients in Ibadan, Nigeria. <b>Methods.</b> Forty HBV-DNA-positive patients were recruited into this study, and the viral load assay and genotyping by nested multiplex PCR were done. The partial X gene region was amplified and Sanger sequenced. The BPC and PC genomic regions were then analysed using bioinformatics. <b>Results.</b> Twenty-three participants recorded HBV DNA viral load of >20 000 IU, while 17 had <20 000 IU and 28 samples were genotyped. Five genotypes (A, B, C, D and E) and four mixed genotypes (AC, AD ACD and ABCD) were detected. Genotype AC was the most frequently encountered, while genotypes E and B were the least encountered. Mutation was highest in ages 34-45 years. Double mutation A1762T and G1764A within the BCP region was the most encountered mutation. <b>Conclusions.</b> We report a diverse HBV genetic landscape, with mixed infections between genotypes with BCP double-mutation A1762T/G1764A, signalling the likelihood of poor HBV-related liver disease prognosis. Our findings contribute to our understanding of the molecular characteristics of HBV and its potential implications for disease progression and management among HBV-infected Nigerians.