title: Molecular characterization of occult hepatitis B virus in genotype E-infected subjects.
abstract: Occult hepatitis B virus (HBV) infection (OBI), defined as the presence of HBV DNA without detectable HBV surface antigen (HBsAg), is frequent in west Africa, where genotype E is prevalent. The prevalence of OBI in 804 blood donors and 1368 pregnant women was 1.7 and 1.5%, respectively. Nine of 32 OBI carriers were evaluated with HBV serology, viral load and complete HBV genome sequence of two to five clones. All samples except one were anti-HBV core antigen-positive and three contained antibodies against HBsAg (anti-HBs). All strains were of genotype E and formed quasispecies with 0.20-1.28% intra-sample sequence variation. Few uncommon mutations (absent in 23 genotype E reference sequences) were found across the entire genome. Two mutations in the core region encoded truncated or abnormal capsid protein, potentially affecting viral production, but were probably rescued by non-mutated variants, as found in one clone. No evidence of escape mutants was found in anti-HBs-carrying samples, as the 'a' region was consistently wild type. OBI carriers constitute approximately 10% of all HBV DNA-viraemic adult Ghanaians. OBI carriers appear as a disparate group, with a very low viral load in common, but multiple origins reflecting decades of natural evolution in an area essentially devoid of human intervention.
authors.affiliation: Division of Transfusion Medicine, Department of Haematology, University of Cambridge, Cambridge, UK.
authors.forename: Astrid
authors.initials: A
authors.lastname: Zahn
authors.affiliation: National Health Service Blood and Transplant, Cambridge Blood Centre, Cambridge, UK.
authors.forename: Chengyao
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Obstetrics and Gynaecology, Komfo Anokye Teaching Hospital, Kumasi, Ghana.
authors.forename: Kwabena
authors.initials: K
authors.lastname: Danso
authors.affiliation: National Health Service Blood and Transplant, Cambridge Blood Centre, Cambridge, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Candotti
authors.affiliation: Transfusion Medicine Unit, Department of Medicine, Komfo Anokye Teaching Hospital, Kumasi, Ghana.
authors.forename: Shirley
authors.initials: S
authors.lastname: Owusu-Ofori
authors.affiliation: Division of Transfusion Medicine, Department of Haematology, University of Cambridge, Cambridge, UK.
authors.forename: Jillian
authors.initials: J
authors.lastname: Temple
authors.affiliation: Division of Transfusion Medicine, Department of Haematology, University of Cambridge, Cambridge, UK.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Allain
mesh_terms: D002353:Carrier State / Q000821:virology*; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D005838:Genotype; D005869:Ghana / Q000453:epidemiology; D006509:Hepatitis B / Q000453:epidemiology / Q000635:transmission / Q000821:virology*; D006510:Hepatitis B Antibodies / Q000097:blood; D006512:Hepatitis B Core Antigens / Q000235:genetics / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D007231:Infant, Newborn; D008969:Molecular Sequence Data; D010802:Phylogeny; D019562:Viral Load
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens