An outbreak of diarrhea in piglets caused by a coronavirus antigenically distinct from transmissible gastroenteritis virus.

Coronavirus-like particles were visualized by electron microscopy in the intestinal contents of piglets during a diarrheal outbreak on a Quebec pig farm. The precipitating antigens of transmissible gastroenteritis virus were not detected in the intestinal contents of diarrheic animals by counter-immunoelectrophoresis. Insignificant antibody titers against transmissible gastroenteritis virus were demonstrated in the sera of convalescent pigs by indirect immunofluorescence and these sera did not react with transmissible gastroenteritis virus when tested by immunoelectron microscopy. The causative agent could not be isolated in cell cultures. It was concluded that a coronavirus antigenically distinct from transmissible gastroenteritis virus was responsible for the enteric problems observed on this farm. The outbreak was controlled after oral inoculation of adult pigs with infected intestinal contents.