Neutralizing and Hemagglutination-Inhibiting Activity of Nasal Secretions Following Experimental Human Infection with A2 Influenza Virus

Abstract

Nasal washes from eight volunteers experimentally infected with A2 influenza virus were collected at frequent intervals prior to and following infection. Total protein and IgA concentrations increased following infection and remained elevated for 3 weeks. An early increase in protein concentration was associated with markedly increased nonspecific HI activity presumably related to the presence of mucoprotein inhibitor. Increased neutralizing activity for the infecting virus strain appeared 10 days following inoculation concurrently with the appearance of serum neutralizing antibody. Specific nasal wash neutralizing antibody was also related to total protein concentration but was consistently demonstrated only after serum neutralizing antibody had increased to significant titers. The presence of nasal wash neutralizing activity to strains not related to the infecting virus was almost associated with elevated nasal secretion protein and IgA concentrations. No serum antibody titer changes to these strains occurred. Nasal secretion A2 influenza neutralizing and HI activities were present following infection in association with 11S IgA predominantly and also 7S immunoglobulins.