title: No increase in prevalence of hepatitis B surface antigen mutant in a population of children and adolescents who were fully covered by universal infant immunization.
abstract: BACKGROUND
  Mutants of the a determinant of hepatitis B surface antigen (HBsAg) can escape neutralization by vaccine-induced antibodies and prevail in an immunized population.
  
  
  METHODS
  We evaluated the a mutants in a pediatric population surveyed in 2004 and compared these findings with the data of previous surveys.
  
  
  RESULTS
  There were 38 children and 74 adolescents who were HBsAg positive, and serum hepatitis B virus (HBV) DNA was obtained and tested from 31 and 34 of them, respectively. The a mutants were found in 7 (22.6%) of 31 HBV DNA-positive children and in 7 (0.10%) of 7234 children, the entire population that was surveyed in 2004. After the beginning of universal immunization, the very low prevalence of mutants has remained unchanged for 20 years. More a mutants were found in immunized than in nonimmunized HBV DNA-positive children aged 1-4 years old (31% vs 4%, P = .016) but not in those children aged 5-12 years old. Approximately 68% of immunized, mutant-infected children had carrier mothers. More a mutants emerged in children immunized with plasma-derived vaccines than in those immunized with recombinant vaccines (14 of 5166 vs 3 of 4970, respectively; P = .04). HBV DNA levels were significantly lower in hepatitis B e antigen-positive sera containing the G145R mutant than were levels in sera containing wild-type virus. HBsAg-negative sera containing a mutants had very low HBV DNA levels.
  
  
  CONCLUSIONS
  Less infectivity of G145R, recombinant vaccine use, and mutant loss with older age seem to decrease the a mutant prevalence in an immunized population over time.
authors.affiliation: Department of Pediatrics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Hong-Yuan
authors.initials: HY
authors.lastname: Hsu
authors.forename: Mei-Hwei
authors.initials: MH
authors.lastname: Chang
authors.forename: Yen-Hsuan
authors.initials: YH
authors.lastname: Ni
authors.forename: Cheng-Lun
authors.initials: CL
authors.lastname: Chiang
authors.forename: Huey-Ling
authors.initials: HL
authors.lastname: Chen
authors.forename: Jia-Feng
authors.initials: JF
authors.lastname: Wu
authors.forename: Pei-Jer
authors.initials: PJ
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000097:blood; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000097:blood / Q000235:genetics / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D032541:Mass Vaccination; D009154:Mutation; D016133:Polymerase Chain Reaction; D016036:Seroepidemiologic Studies; D013624:Taiwan / Q000453:epidemiology; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology
chemical_list: D004279:DNA, Viral; D000939:Epitopes; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D014614:Vaccines, Synthetic