| Abstract: | Groups of two or three day old pigs were inoculated intravenously with cell culture grown transmissible gastroenteritis virus. A single or a multiple dosage schedule was used. The magnitude of immune response was measured in terms of serum neutralization indices. A single dose of relatively attenuated virus caused mild clinical signs of transmissible gastroenteritis infection in the pigs and induced a low level of antibody in the serum by the seventh day after inoculation. Repeated injections of virus at seven day intervals stimulated little increase in antibody titers. However, high serum antibody titers were obtained for all pigs if the time interval between injections was extended to 15 days. Sera obtained early after exposure to live transmissible gastroenteritis virus contained mainly IgM antibody whereas sera obtained later after exposure contained mainly IgG antibody. Ten plaque purified isolates of transmissible gastroenteritis virus, comprising eight American isolates, one Japanese isolate and one British isolate were indistinguishable by means of reciprocal plaque reduction neutralization tests. |
