title: Occult Hepatitis B Virus Infection in Nigerian Blood Donors and Hepatitis B Virus Transmission Risks.
abstract: BACKGROUND
  Occult hepatitis B virus infection (OBI) characterized by the absence of detectable HBsAg remains a potential threat in blood safety. We investigated the actual prevalence, viral factors and genotype of OBI infections in Nigerian blood donors.
  
  
  METHODS
  Serum collected from two blood banks were reconfirmed as HBsAg seronegative by ELISA. Forty HBsAg positive samples were employed as controls. HBV-DNA was amplified from all donors and viral loads were determined using quantitative real-time PCR. Antibodies to the HBV core, surface and HBe antigen (anti-HBc,anti-HBs,HBeAg) were measured. The PreS/S and PreC/C regions of the HBV genome were sequenced.
  
  
  RESULTS
  Of the 429 blood donors, 72(17%) were confirmed as OBI by DNA detection in different reference labs and excluded the concern of possible contamination. Of the 72 OBI samples, 48(67%) were positive for anti-HBc, 25(35%) positive for anti-HBs, and 2(3%) positive for HBeAg. Of the 72 OBI samples, 31(43%) were seropositive for either anti-HBc, anti-HBs or HBeAg, 21 (30%) positive for both anti-HBc and anti-HBs,one positive for both anti-HBc and HBeAg. None of the OBI samples were positive for all three serological markers. The viral load was <50copies/ml in the OBI samples and genotype E was predominant. The L217R polymorphism in the reverse transcriptase domain of the HBV polymerase gene was observed significantly higher in OBI compared with HBsAg positive individuals (P<0.0001).
  
  
  CONCLUSIONS
  High incidence of OBI is relevant in high endemic areas worldwide and is a general burden in blood safety. This study signifies the high prevalence of OBI and proposes blood donor samples in Nigeria should be pre-tested for OBI by nucleic acid testing (NAT) and/or anti-HBc prior to transfusion to minimize the HBV infection risk.
authors.affiliation: Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Deparment of Medical Microbiology and Parasitology, Ladoke Akintola University of Technology, Ogbomosho, Nigeria.
authors.forename: Opaleye O
authors.initials: OO
authors.lastname: Oluyinka
authors.affiliation: Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
authors.forename: Hoang Van
authors.initials: HV
authors.lastname: Tong
authors.affiliation: Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany; Department of Molecular Biology, 108 Military Central Hospital, Hanoi, Vietnam.
authors.forename: Sy
authors.initials: S
authors.lastname: Bui Tien
authors.affiliation: Deparment of Medical Microbiology and Parasitology, Ladoke Akintola University of Technology, Ogbomosho, Nigeria.
authors.forename: Ademola H
authors.initials: AH
authors.lastname: Fagbami
authors.affiliation: Obafemi Awolowo University, Ile Ife, Nigeria.
authors.forename: Olusegun
authors.initials: O
authors.lastname: Adekanle
authors.affiliation: Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Deparment of Medical Microbiology and Parasitology, Ladoke Akintola University of Technology, Ogbomosho, Nigeria.
authors.forename: Olusola
authors.initials: O
authors.lastname: Ojurongbe
authors.affiliation: Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany; Department of Molecular Pathology, University of Tübingen, Tübingen, Germany.
authors.forename: C-Thomas
authors.initials: CT
authors.lastname: Bock
authors.affiliation: Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kremsner
authors.affiliation: Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Fondation Congolaise pour la Recherche Medicale, Brazzaville, Republic of Congo.
authors.forename: Thirumalaisamy P
authors.initials: TP
authors.lastname: Velavan
mesh_terms: D000328:Adult; D001782:Blood Donors; D058731:Blood Safety / Q000379:methods; D003141:Communicable Diseases / Q000453:epidemiology / Q000276:immunology / Q000821:virology; D004279:DNA, Viral / Q000276:immunology; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology* / Q000276:immunology / Q000635:transmission* / Q000821:virology; D006510:Hepatitis B Antibodies / Q000276:immunology; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000276:immunology; D006513:Hepatitis B e Antigens / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology*; D006801:Humans; D008297:Male; D009549:Nigeria; D015995:Prevalence; D012306:Risk; D065227:Transfusion Reaction; D019562:Viral Load / Q000276:immunology
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens