title: Discordant diagnostic results due to a hepatitis B virus T123A HBsAg mutant.
abstract: HBsAg immunoassay results are occasionally discordant among primary and confirmatory assays or with respect to other markers of HBV infection. Such discordance has been observed repeatedly in Canada with samples having a mutation at HBsAg codon 123 (sT123A). Detection of recombinant expressed HBsAg protein having either sT123 or sA123 was evaluated with one manual and six automated HBsAg immunoassays. The recombinant mutant HBsAg was non-reactive by Abbott AxSYM, while the Abbott ARCHITECT Quantitative and Qualitative II, ADVIA Centaur, and VITROS ECi detection signal was reduced compared with the wild-type protein, approaching the assay cut-off for certain assays, dependent upon the level of protein. The Roche Elecsys and manual immunoassays detected both wild-type and mutant proteins comparatively. The sT123A mutation leads to loss of detection by immunoassays commonly used in Canadian diagnostic laboratories, which may produce misleading results and diagnoses.
authors.affiliation: Bloodborne Pathogens and Hepatitis, Division of Viral Diseases, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington St., Winnipeg, MB, Canada, R3E 3R2. Electronic address: carla.osiowy@phac-aspc.gc.ca.
authors.forename: Carla
authors.initials: C
authors.lastname: Osiowy
authors.affiliation: Bloodborne Pathogens and Hepatitis, Division of Viral Diseases, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington St., Winnipeg, MB, Canada, R3E 3R2. Electronic address: kaarina.kowalec@alumni.ubc.ca.
authors.forename: Kaarina
authors.initials: K
authors.lastname: Kowalec
authors.affiliation: Bloodborne Pathogens and Hepatitis, Division of Viral Diseases, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington St., Winnipeg, MB, Canada, R3E 3R2. Electronic address: elizabeth.giles@phac-aspc.gc.ca.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Giles
mesh_terms: D000328:Adult; D002170:Canada; D003951:Diagnostic Errors; D005260:Female; D006509:Hepatitis B / Q000175:diagnosis* / Q000821:virology; D006514:Hepatitis B Surface Antigens / Q000097:blood* / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008875:Middle Aged; D050505:Mutant Proteins / Q000097:blood* / Q000235:genetics; D017354:Point Mutation
chemical_list: D006514:Hepatitis B Surface Antigens; D050505:Mutant Proteins
keywords: Diagnostic immunoassay; Escape; HBV; HBsAg; Mutant