Abstract:
Background: Previous studies in Nigeria have reported the presence of hepatitis B virus
(HBV) genotype E and the availability of immune escape mutants. There is a paucity of data
on chronic patients on long-term antiviral therapy for HBV infection.
Objective: This study assessed HBV genotypes and drug resistance variants among patients
with chronic HBV infection receiving tenofovir in Jos, Nigeria.
Methods: This cross-sectional study consecutively enrolled 101 patients (51 with HIV/HBV
co-infection and 50 with HBV infection only) on antiviral therapy from February 2018 to May
2019 at four hospitals in Jos, Nigeria. DNA quantification of HBV was performed on all
samples; 30 samples with detectable viral load were selected for genotyping using Sanger
sequencing by targeting the full-length sequences of reverse transcriptase gene of the
HBV genome. Phylogenetic analysis was performed with reference sequences from GenBank.
Escape mutant and drug resistance analysis were performed using HBV drug resistance
interpretation and Geno2pheno.
Results: Only 30 (29.7%) of the 101 study participants had detectable HBV DNA. Of these,
six (20.0%) isolates were successfully amplified and sequenced. The identified genotype was E,
including escape mutations L127R (16.7%) and G145A (16.7%).
Conclusion: This study revealed exclusive dominance of genotype E in Nigeria. The S gene
mutations G145A and L271R are known to be associated with modified antigenicity and
impaired serologic assays, which may cause false negatives in the detection of anti-HBV
surface antigen. The presence of mutants that are associated with vaccine immune escape
may also have diagnostic and vaccine immune response implications.
