Isolation of Porcine Immunoglobulins and Determination of the Immunoglobulin Classes of Transmissible Gastroenteritis Viral Antibodies1

serum, colostrum, and milk in an attempt to identify the immunoglobulin classes of neutralizing antibodies to the porcine enteric virus, transmissible gastroenteritis (TGE). The results of these absorption studies suggest that in colostrum and milk from sows experimentally (orally) or naturally infected with live virulent TGE virus, IgA is the predominant immunoglobulin class of TGE antibodies. Both IgA and IgG TGE antibodies appeared to be present in the serum from these sows, but with IgG TGE antibodies predominating. In contrast, in the serum, colostrum and milk from sows vaccinated intramuscularly or intramammarily with live attenuated TGE virus, the TGE antibody activity was associated mainly with the IgG class of immunoglobulins. These results provide additional data indicating that the route of infection or vaccination markedly influences the immunoglobulin class of antibodies in colostrum and milk. Secondly, IgA antibodies in mammary secretions are probably essential for providing optimal passive immunity of nursing pigs against infection with TGE virus.