title: Hepatitis B virus infection in post-vaccination South Africa: occult HBV infection and circulating surface gene variants.
abstract: OBJECTIVE
  The aim of this study was to investigate the prevalence of occult hepatitis B virus (HBV) infection and the HBV surface (S) gene variants circulating in the South African population after nearly two decades of universal hepatitis B vaccination.
  
  
  METHODS
  From a previous serosurvey, 201 serum samples with serological evidence of exposure to HBV were identified and these were stratified into post- and pre-vaccine introduction populations. For all samples, HBV DNA was screened and quantified using a real-time PCR assay and results analysed together with HBV serological markers. Where HIV results were available, subset analysis was performed. The HBV S gene was PCR-amplified and sequences analysed for a total of 37 isolates.
  
  
  RESULTS
  The prevalence of occult HBV infection reduced from 70.4% in the pre-vaccine introduction era to 66.0% post-vaccine introduction. There was an association between HIV infection and an increase in prevalence of occult HBV infection within the post-vaccine introduction population, although this was not statistically significant. Furthermore, sequence analysis revealed the following HBV subgenotypes; A1 (n=34), A2 (n=2) and a rare D4 isolate. HBV S gene variants, including diagnostic escape mutants were isolated.
  
  
  CONCLUSIONS
  There was a decline in the prevalence of occult HBV infection in post-vaccination South Africa, although the disease burden remains significant in the HIV co-infected population. After nearly two decades of a universal hepatitis B vaccination programme, no positive selection of vaccine escape mutants were observed.
authors.affiliation: HIV and Hepatitis Research Unit, Department of Virology, University of Limpopo (Medunsa Campus) and National Health Laboratory Service, Pretoria, South Africa.
authors.forename: Edina
authors.initials: E
authors.lastname: Amponsah-Dacosta
authors.affiliation: HIV and Hepatitis Research Unit, Department of Virology, University of Limpopo (Medunsa Campus) and National Health Laboratory Service, Pretoria, South Africa.
authors.forename: Ramokone L
authors.initials: RL
authors.lastname: Lebelo
authors.affiliation: HIV and Hepatitis Research Unit, Department of Virology, University of Limpopo (Medunsa Campus) and National Health Laboratory Service, Pretoria, South Africa.
authors.forename: J Nare
authors.initials: JN
authors.lastname: Rakgole
authors.affiliation: HIV and Hepatitis Research Unit, Department of Virology, University of Limpopo (Medunsa Campus) and National Health Laboratory Service, Pretoria, South Africa.
authors.forename: Selokela G
authors.initials: SG
authors.lastname: Selabe
authors.affiliation: HIV and Hepatitis Research Unit, Department of Virology, University of Limpopo (Medunsa Campus) and National Health Laboratory Service, Pretoria, South Africa.
authors.forename: Maemu P
authors.initials: MP
authors.lastname: Gededzha
authors.affiliation: Department of Medical Virology, University of Pretoria/Tshwane Academic Division of NHLS, Pretoria, South Africa.
authors.forename: Simnikiwe H
authors.initials: SH
authors.lastname: Mayaphi
authors.affiliation: Division of Digestive Diseases, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: Eleanor A
authors.initials: EA
authors.lastname: Powell
authors.affiliation: Division of Digestive Diseases, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Blackard
authors.affiliation: HIV and Hepatitis Research Unit, Department of Virology, University of Limpopo (Medunsa Campus) and National Health Laboratory Service, Pretoria, South Africa. Electronic address: jeffrey.mphahlele@mrc.ac.za.
authors.forename: M Jeffrey
authors.initials: MJ
authors.lastname: Mphahlele
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000097:blood* / Q000737:chemistry / Q000235:genetics; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology* / Q000517:prevention & control*; D006514:Hepatitis B Surface Antigens / Q000097:blood* / Q000235:genetics; D017325:Hepatitis B Vaccines / Q000008:administration & dosage*; D006801:Humans; D007223:Infant; D008297:Male; D050505:Mutant Proteins / Q000097:blood / Q000235:genetics; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013019:South Africa / Q000453:epidemiology; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D050505:Mutant Proteins
keywords: Diagnostic escape mutants; HIV infection; Hepatitis B vaccine; Occult HBV infection; Subgenotype D4