Coronavirus-like particles in laboratory rabbits with different syndromes in the Netherlands.

Virus-like particles were identified from the plasma of rabbits which developed pleural effusion disease after inoculation with different strains of Treponema pallidum. These particles were considered coronavirus-like on the basis of their size, morphology, and buoyant density. Clinical and pathological manifestations of pleural effusion disease, which is probably the same disease entity as rabbit cardiomyopathy, resembled those of feline infectious peritonitis which is caused by another probable member of the Coronaviridae family. Coronavirus-like particles also were demonstrated in the feces of rabbits which had been inoculated with a 450-nm fecal filtrate of rabbits which died from infectious intestinal disease.