Detection and circulation of hepatitis B virus immune escape mutants among asymptomatic community dwellers in Ibadan, southwestern Nigeria.
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 subtyped 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.
Department of Virology, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria; Department of Microbiology, Faculty of Science, Ekiti State University, Ado Ekiti, Ekiti State, Nigeria. Electronic address: faleyetemitope@gmail.com.
Temitope Oluwasegun Cephas
TO
Faleye
Department of Virology, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria. Electronic address: adewumi1@hotmail.com.
Olubusuyi Moses
OM
Adewumi
Department of Surgery, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria. Electronic address: maryjoy1023@yahoo.ca.
Ijeoma Maryjoy
IM
Ifeorah
Department of Medicine, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria. Electronic address: adeakere@yahoo.co.uk.
Adegboyega
A
Akere
Institute for Advanced Medical Research and Training, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria. Electronic address: drbakarey@yahoo.com.
Adeleye Solomon
AS
Bakarey
Institute of Child Health, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria. Electronic address: omochukwu2001@yahoo.com.
Ewean Chukwuma
EC
Omoruyi
Department of Science Laboratory Technology, Faculty of Science, Ekiti State University, Ado Ekiti, Ekiti, State, Nigeria. Electronic address: oluwakemisolavera@gmail.com.
Kemi
K
Oketunde
Department of Science Laboratory Technology, Faculty of Science, Ekiti State University, Ado Ekiti, Ekiti, State, Nigeria. Electronic address: b_jummy@yahoo.com.
Oluwajumoke Bosede
OB
Awonusi
Department of Microbiology, Faculty of Science, Ekiti State University, Ado Ekiti, Ekiti State, Nigeria. Electronic address: ajayimodupe@yahoo.com.
Modupe Racheal
MR
Ajayi
Department of Virology, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria; WHO National Polio Laboratories, University of Ibadan, Ibadan, Oyo State, Nigeria. Electronic address: adek1808@yahoo.com.
Johnson Adekunle
JA
Adeniji
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009549:Nigeria; D010802:Phylogeny; D055815:Young Adult
D006514:Hepatitis B Surface Antigens
HBV; Hepatitis B virus; IEM; Ibadan; Immune escape mutant; Nigeria