Intestinal, pulmonary, and serum antibody responses of feeder pigs exposed to transmissible gastroenteritis virus by the oral and the oral-intranasal routes in inoculation.

Specific antibodies against transmissible gastroenteritis (TGE) virus produced as a result of oral and oral-intranasal viral exposure of feeder pigs were isolated by molecular sieve column chromatography of lung wash, intestinal fluid, and serum samples. Selected fractions were analyzed for neutralizing antibody activity. Oral inoculation gave a predominantly immunoglobulin (Ig) G antibody response in lung wash and serum, as compared with the response in intestinal fluid in which neutralizing antibody activity was found in the IgA-containing fractions. Oral-intranasal inoculation produced a predominantly IgA antibody response in intestinal fluid. Lung wash contained IgA and IgG antibody, and serum antibody consisted primarily of IgG class of Ig. Neutralizing antibody (IgA, IgG, IgM) from the lung wash, intestinal fluid, and serum samples persisted beyond 56 days after oral and oral-intranasal viral exposures. The virus-shedding period in feces was 1 to 7 days after oral or oral-intranasal inoculation of feeder swine with virulent TGE virus. However, TGE virus was reisolated from lung and intestinal tissue for as long as 42 and 56 days, respectively.