Virologic Polymorphism of Occult Hepatitis B Infection (OBI) Among Blood Donors in Abuja.

Occult Hepatitis B Infection (OBI) represents a major public health challenge in sub-Saharan Africa, especially in Nigeria, where HBV is endemic and molecular diagnostics are scarce. This study aimed to investigate the virologic polymorphisms of OBI among blood donors in Abuja, focusing on genotypic variation and mutations that enable diagnostic escape. A total of 250 HBsAg-negative blood donors aged 18–60 years were enrolled in this cross-sectional study. Samples were tested using the HBV-5 panel (Aria rapid kit) and confirmed through quantitative real-time PCR for HBV-DNA and viral load. DNA-positive samples underwent sequencing of S, X, and P genes to determine HBV genotypes. Of the 250 donors used, only 37 were vaccinated against HBV. Vaccinated donors exhibited 0.4% HBcAb with a viral load of 37.0 IU/ml. Unvaccinated donors showed 2.8% HBcAb, 0.8% HBeAg, and 1.2% HBeAb, with a mean viral load of 129.8 ± 11.3 IU/ml. All OBI isolates belonged to genotype E, with gene segment coverage: p-gene (LC 515470.1) at 98.25%, s-gene (LC 515465.1) at 99.0%, p-gene (LC 515470.1) at 97.89%, and S-gene (FN281477.1) at 92.0%., while no pre-S or Pre-core mutations were identified. These findings underscore a significant risk of transfusion-transmitted HBV, emphasizing the importance of nucleic acid testing (NAT) beyond HBsAg screening to enhance blood safety.