Immunodiffusion studies on the myxoviruses. II. Identification of influenza A/PR8 precipitins in the serum of normal rabbits

Abstract

An investigation has been made to determine whether influenza virus precipitins, detected in the serum of normal rabbits, are immunoglobulins or non-specific inhibitors of virus haemagglutination. Of 12 normal rabbit sera screened by immunodiffusion reactions for the presence of these precipitins, 6 sera were found to be positive. Serum treatments for the removal of non-specific HA inhibitors, i.e. heat, periodate, trypsin, and neuraminidase, did not completely inactivate either the haemagglutination-inhibiting or the precipitating activity of the normal serum. Fractionation studies for the isolation and identification of the serum fraction responsible for the precipitating activity included DEAE-cellulose adsorption, rivanol treatment, and ammonium sulfate precipitation. The active component in the normal serum snowed a reaction of identity with specific antibodies against influenza virus contained in the gamma globulin fraction of immune serum. It is concluded that the precipitating component detected in the serum of some normal rabbits is immunoglobulin, presumably arising as a result of natural infection.