title: Emergence of an S gene mutant during thymosin alpha1 therapy in a patient with chronic hepatitis B.
abstract: The presence of a hepatitis B virus S gene mutant was investigated in a patient being treated with thymosin alpha1. He was seropositive for hepatitis B e antigen throughout therapy but was intermittently seronegative for hepatitis B surface antigen (HBsAg) by an RIA. Sequence analysis revealed an S gene mutant in HBsAg-seronegative serum with two consecutive amino acid substitutions: threonine115-to-isoleucine and threonine116-to-asparagine, whereas no amino acid substitution or deletion was found in the pre-S region. A site-directed mutagenesis experiment confirmed that these mutations were responsible for the failure to detect HBsAg. In summary, an S gene mutant was identified in an HBsAg-seronegative patient. The mutations were located outside the putative "a" determinant. The emergence of an S gene mutant during thymosin alpha1 treatment suggests that enhanced host immunity against HBsAg may play a role in its antiviral activity.
authors.affiliation: Department of Pathology, Chang Gung Memorial Hospital and University, Taipei, Taiwan.
authors.forename: J H
authors.initials: JH
authors.lastname: Tang
authors.forename: C T
authors.initials: CT
authors.lastname: Yeh
authors.forename: T C
authors.initials: TC
authors.lastname: Chen
authors.forename: S Y
authors.initials: SY
authors.lastname: Hsieh
authors.forename: C M
authors.initials: CM
authors.lastname: Chu
authors.forename: Y F
authors.initials: YF
authors.lastname: Liaw
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000627:therapeutic use*; D005814:Genes, Viral; D006514:Hepatitis B Surface Antigens / Q000235:genetics* / Q000276:immunology; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology; D019694:Hepatitis B, Chronic / Q000097:blood / Q000188:drug therapy / Q000276:immunology / Q000821:virology*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D000077596:Thymalfasin; D013947:Thymosin / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D000998:Antiviral Agents; D006514:Hepatitis B Surface Antigens; D013947:Thymosin; D000077596:Thymalfasin