Prevalence of hepatitis B virus core antibodies among blood donors in Nigeria: Implications for blood safety.

Background: Anti-hepatitis B core antibody (anti-HBc) testing improves transfusion safety by detecting past and current hepatitis B virus (HBV) infection while detecting hepatitis B surface antigen (HBsAg) in serology-negative HBV infection. However, occult HBV infection (OBI) (serum or liver HBV DNA-positive but HBsAg-negative) remains unaddressed among replacement blood donors - family members or friends who donate to replace blood transfused to a relative. Objective: This study assessed risk factors for a positive anti-HBc test among donors with OBI and determined the anti-HBc-positive status of replacement donors. Methods: The study was conducted at the University College Hospital Blood Bank, Ibadan, Nigeria, using blood samples collected from blood donors between April 2019 and May 2019. Donors were screened for HBsAg by rapid diagnostic test (RDT) and enzyme-linked immunosorbent assay (ELISA) and anti-HBc by ELISA, while HBV DNA was detected using a semi-nested polymerase chain reaction. Results: Of the 274 participants, 15 (5.5%) were HBsAg-positive by RDT and 36 (13.1%) by ELISA, while 133 (48.5%) were anti-HBc positive. Out of 232 HBsAg-negative donors, 107 (46.1%) were anti-HBc positive. Of the 107 HBsAg-negative but anti-HBc-positive samples, only one (0.93%) was HBV DNA-positive. The HBV DNA-positive donor was HBsAg-negative by both RDT and ELISA tests. Conclusion: This study establishes a potential risk for HBV transmission from isolated anti-HBc-positive donors to blood recipients. HBc immunoglobulin (antibody) M testing to identify blood units requiring further screening with polymerase chain reaction to detect OBI can prevent HBV transmission through blood transfusion.

Multiple expansions of globally uncommon SARS-CoV-2 lineages in Nigeria.

Disparities in SARS-CoV-2 genomic surveillance have limited our understanding of the viral population dynamics and may delay identification of globally important variants. Despite being the most populated country in Africa, Nigeria has remained critically under sampled. Here, we report sequences from 378 SARS-CoV-2 isolates collected in Oyo State, Nigeria between July 2020 and August 2021. In early 2021, most isolates belonged to the Alpha "variant of concern" (VOC) or the Eta lineage. Eta outcompeted Alpha in Nigeria and across West Africa, persisting in the region even after expansion of an otherwise rare Delta sub-lineage. Spike protein from the Eta variant conferred increased infectivity and decreased neutralization by convalescent sera in vitro. Phylodynamic reconstructions suggest that Eta originated in West Africa before spreading globally and represented a VOC in early 2021. These results demonstrate a distinct distribution of SARS-CoV-2 lineages in Nigeria, and emphasize the need for improved genomic surveillance worldwide.

Coincident rapid expansion of two SARS-CoV-2 lineages with enhanced infectivity in Nigeria.

The emergence of new SARS-CoV-2 variants with enhanced transmissibility or decreased susceptibility to immune responses is a major threat to global efforts to end the coronavirus disease 2019 (COVID-19) pandemic. Disparities in viral genomic surveillance capabilities and efforts have resulted in gaps in our understanding of the viral population dynamics across the globe. Nigeria, despite having the largest population of any nation in Africa, has had relatively little SARS-CoV-2 sequence data made publicly available. Here we report the whole-genome sequences of 74 SARS-CoV-2 isolates collected from individuals in Oyo State, Nigeria in January 2021. Most isolates belonged to either the B.1.1.7 Alpha "variant of concern" or the B.1.525 Eta lineage, which is currently considered a "variant of interest" containing multiple spike protein mutations previously associated with enhanced transmissibility and possible immune escape. Nigeria has the highest reported frequency of the B.1.525 lineage globally with phylogenetic characteristics consistent with a recent monophyletic origin and rapid expansion. Spike protein from the B.1.525 lineage displayed both increased infectivity and decreased neutralization by convalescent sera compared to Spike proteins from other clades. These results, along with indications that the virus is outpacing the B.1.1.7 lineage in Nigeria, suggest that the B.1.525 lineage represents another "variant of concern" and further underline the importance of genomic surveillance in undersampled regions across the globe.

Assessment of hepatitis B surface antigen negative blood units for HBV DNA among replacement blood donors in a hospital based blood bank in Nigeria.

BACKGROUND: Hepatitis B virus infection is one of the greatest threats to blood safety all over the world. The laboratory algorithm based on only the detection of hepatitis B surface antigen (HBsAg) leaves a gap for infected HBsAg negative donors to donate blood during the "window period" (WP) and late stages of infection. OBJECTIVE: To estimate the frequency of the presence of HBV deoxyribonucleic acid (DNA) in HBsAg negative blood units screened using two different assays for HBsAg in a high endemic region. METHODS: Frozen serum aliquot of 100 replacement blood donors who donated blood units that were HBsAg negative were retrieved and tested for HBV DNA. Sample positive for HBV DNA was sequenced by Sanger's method, genotyped and the viral load was determined. RESULTS: One sample (1%) was positive for HBV DNA. The HBV viral load of the sample was 768,000 IU/ml. The partial S-gene of the Hepatitis B virus isolated was genotype E using the NCBI viral genotyping tool. CONCLUSIONS: There is still a risk of HBV infected blood unit escaping detection when donor testing is limited to HBsAg screening. The use of NAT which can substantially reduce HBV infected blood donors from the donor pool should be considered.