Porcine pararotavirus: detection, differentiation from rotavirus, and pathogenesis in gnotobiotic pigs

Abstract

Some characteristics of a newly recognized porcine enteric virus are described. Tentatively, the virus was referred to as porcine pararotavirus (PaRV) because it resembled rotaviruses in respect to size, morphology and tropism for villous enterocytes of the small intestine. It was antigenically distinct from porcine, human and bovine rotaviruses and reoviruses 1, 2 and 3, and the electrophoretic migration pattern of PaRV double-stranded RNA was distinct from the electrophoretic migration patterns of the rotaviral and reoviral genomes. By passage in gnotobiotic pigs, PaRV was isolated from 2 suckling diarrheic pigs originating from 2 herds. After oral exposure of gnotobiotic pigs, villous enterocytes of the small intestines became infected as judged by immunofluorescence, resulting in villous atrophy and diarrhea. Mortality was high when gnotobiotic pigs < 5 days old were infected. The C strain of this virus was serially passed 10 times in gnotobiotic pigs and EM, immunofluorescence and serological tests indicated no extraneous agents. The virus was serially passed 5 times in cell cultures which contained pancreatin in the medium, but replication was negligible or absent, as the number of immunofluorescent cells decreased with each passage. Since rotaviral infections are frequently diagnosed by direct EM of fecal specimens, the presence of other morphologically similar viruses, such as PaRV, should be considered. The use of immune EM is suggested as a means of helping recognize this situation.