Characterization of influenza antibodies by serum absorption

Absorptions of sera from groups of persons, both normal and after vaccination, resulted in complete removal of antibody to all strains of influenza virus within a type when a strain of antigenic configuration similar to that presumed to be the strain of first experience was employed. Absorption of these sera with strains encountered after the primary antigenic stimulus, removed antibody to strains recently experienced, but failed to absorb the primary antibody. By these methods, three age groups could be distinguished whose characteristic principal antibody was oriented to react with maximal efficiency either with FM1 or PR8 or Swine/1976 influenza viruses. Persons in these age groups had an initial experience with strains of the respective antigenic characteristics found in the variants of influenza virus mentioned. Basis for understanding these results was obtained with sera from successively infected ferrets, when serum absorptions demonstrated all type-specific antibody was oriented to react only with the strain of first infection. In view of this evidence there can now be little doubt as to the marked persistent influence an antigenic experience with influenza virus has upon the antibody-forming mechanisms of the virgin host.