title: Hepatitis B escape mutants in Scottish blood donors.
abstract: Hepatitis B virus (HBV) remains as the viral infection with the highest risk of transmission by transfusion. This risk is associated with window period donations, occult HBV infection (OBI) and the emergence of escape mutants, which render blood donations false negative for hepatitis B surface antigen (HBsAg) serological testing. A retrospective study was conducted to gain insights into the molecular epidemiology of HBV escape mutants in Scottish blood donors. The criterion for selection was HBV positivity either by serology or nucleic acid testing (NAT). HBsAg detection was compared across several commercial immunoassays. The full length S gene from plasma samples was PCR amplified, cloned and expressed in HepG2 cells. Eight samples showed HBsAg discordant results, while 5 OBI samples were found. Four escape mutants, containing missense mutations in the S gene, are described here. These mutations impaired HBsAg detection both from HBV infected plasma samples and from recombinant proteins derived from its infected donors. Phylogenetic analysis showed that most of the mutants were clustered in the genotype D and were closely related to strains from Asia and the Middle East. We report here a proline substitution, outside the major hydrophilic region, that impaired HBsAg detection in vivo and in vitro, warning about the risk for the emergence of vaccine escape mutants with mutations outside the major neutralisation site.
authors.affiliation: Microbiology and Components Group, RDI, Scottish National Blood Transfusion Service/NHS, 21 Ellen's Glen Road, Edinburgh, EH17 7QT, UK. olarralde-diaz@nhs.net
authors.forename: Osmany
authors.initials: O
authors.lastname: Larralde
authors.forename: Brian
authors.initials: B
authors.lastname: Dow
authors.forename: Lisa
authors.initials: L
authors.lastname: Jarvis
authors.forename: Fiona
authors.initials: F
authors.lastname: Davidson
authors.forename: Juraj
authors.initials: J
authors.lastname: Petrik
mesh_terms: D001782:Blood Donors; D002460:Cell Line; D003001:Cloning, Molecular; D016000:Cluster Analysis; D015870:Gene Expression; D006509:Hepatitis B / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology*; D006514:Hepatitis B Surface Antigens / Q000235:genetics / Q000276:immunology; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D017720:Molecular Epidemiology; D050505:Mutant Proteins / Q000235:genetics / Q000276:immunology; D020125:Mutation, Missense; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D012606:Scotland; D017422:Sequence Analysis, DNA
chemical_list: D006514:Hepatitis B Surface Antigens; D050505:Mutant Proteins