Highlights
- •We confirmed presence of HBV IEM in Ibadan, Southwest Nigeria.
- •It shows for the first time that HBV IEMs are circulating in the region.
- •It also confirms the inclusion of Nigeria in the genotype E crescent.
- •Need for multiple HBV classification algorithms for isolates typing was confirmed.
- •HBV DNA detection alone is not sufficient for diagnosis.
Abstract
Background
In
2012, the first Nigerian Hepatitis B Virus (HBV) immune escape mutant
(IEM) case was detected in a pregnant woman in southwestern Nigeria.
Consequently, this study was designed to investigate the presence and
possible circulation of IEMs amongst asymptomatic community dwellers in
southwestern Nigeria.
Methods
Blood
specimens collected from 438 asymptomatic community dwellers were
screened for HBsAg using ELISA technique. Subsequently, the S-gene was
amplified in HBsAg positive samples by a nested PCR protocol, and
amplicons sequenced. Isolates were then subtyped by amino acid residues
at positions 122, 127, 134 and 160, and genotyped by phylogenetic
analysis.
Results
Of the 31 (7.08%)
samples positive for HBsAg, the ∼408 bp Sgene fragment was successfully
amplified and sequenced in 27. Samples obtained from 4 patients could
not be amplified due to low titres. Sequence data from only 15 of the
isolates could be analysed further as eight of the remaining 12 had
multiple peaks while the rest three showed no similarity to any HBV gene
when subjected to BLAST analysis. Thirteen of the 15 isolates were
identified as genotype E. Eleven of which were subtypeed as ayw4 while
the remaining two could not be subtyped due to sR122Q/P substitutions.
The last two isolates that could not be genotyped and subtyped had other
mutations in the “a‟ determinant associated with IEMs.
Conclusions
This
study confirmed presence and circulation of HBV IEM in Nigeria, the
country's inclusion in the genotype E crescent, and the value of
phylogenetic analysis in HBV identification.
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