title: Re-exposure to wild-type virus stabilizes measles-specific antibody levels in late convalescent patients.
abstract: BACKGROUND
  Infection with wild-type (wt) measles virus strains induces high antibody levels believed to provide life-long protection against disease.
  
  
  OBJECTIVE
  Humoral immunity was followed up in convalescent measles patients to assess the persistence of specific antibodies after measles disease in individuals without and with documented re-exposure to wt virus.
  
  
  METHODS
  Paired sera were collected from 43 late convalescents (LC) before re-exposure and 3.7-4.8 years after re-exposure to at least one measles patient (LC+ group). Antibody persistence in this group was compared to paired sera from 43 age- and sex-matched controls without documented exposure to wt virus (LC- group). Paired sera were also obtained from 26 measles patients 1.3-1.7 and 3.8-4.1 years after they had recovered from measles to observe the waning of antibodies in early convalescents (EC group).
  
  
  RESULTS
  Antibody levels decreased by 12.1% (CI: 3.2-20.3%, p=0.01) within 6.3 years in the LC- group of late convalescent measles patients. In contrast, in the LC+ group GMT of first and second sera were virtually identical, indicating that exposure to wt virus stabilizes antibody levels even in absence of a detectable secondary immune response. In a subset of late convalescents of group LC+ with a secondary immune response, antibody waning after re-exposure was as high as 15.6%/year (CI: 13.0-17.7%/year), corresponding to a half-life of 4.1 years (CI: 3.5-5.0 years), but antibodies were still higher than before re-exposure. In the EC group GMT decreased by 6.5% (95% CI: -13.3% to +0.1%) during 2.5 years but significance was low (p=0.08).
  
  
  CONCLUSIONS
  The maintenance of antibody levels in convalescent measles patients is at least partially dependant on recurrent exposure to circulating wt virus.
authors.affiliation: Institute of Immunology and WHO Collaborative Centre for Measles and WHO European Regional Reference Laboratory for Measles and Rubella, Laboratoire National de Santé, 20A Rue Auguste Lumière, L-1011 Luxembourg.
authors.forename: Jacques R
authors.initials: JR
authors.lastname: Kremer
authors.forename: Fabienne B
authors.initials: FB
authors.lastname: Bouche
authors.forename: François
authors.initials: F
authors.lastname: Schneider
authors.forename: Claude P
authors.initials: CP
authors.lastname: Muller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000097:blood*; D000918:Antibody Specificity; D002648:Child; D002675:Child, Preschool; D003289:Convalescence; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D008457:Measles / Q000276:immunology* / Q000821:virology*; D008459:Measles virus / Q000276:immunology / Q000472:pathogenicity*; D008875:Middle Aged; D013997:Time Factors
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G