7S IgM and IgA Influenza Fluorescent Antibodies in Serum

IgM antibodies following the injection of formalinized influenza virus vaccine in adjuvant have been demonstrated in the serum of mice (1) and in rabbits following intravenous administration of live virus (2) but others have reported that no significant antibody in either the IgM or IgA classes appeared in the serum of human volunteers infected by nasal spraying with live influenza virus (3). Although neutralizing antibodies developed to high titers the latter authors stated that all serum antibody was of the IgG type. Since both IgM and IgA antibodies were readily detected in human sera following naturally acquired rubella (4, 5) and mumps (6) by the indirect fluorescent antibody (FA) technique the same procedure was employed to ascertain whether these antibodies were present in persons convalescent from naturally acquired influenza infections. Although brilliant stain was obtained with such sera the reaction was not eliminated by treatment with 2-mercaptoethanol as with the other viral antibodies and therefore contamination of the conjugate by antibodies against IgG was suspected.