Bovine Enteroviruses in the Calf: An Attempt at Serologic, Biologic, and Pathologic Classification

Abstract

SUMMARY Bovine enteroviruses were classified into 8 serotypes to provide a basis for pathogenicity studies. Oral and subcutaneous inoculation of virus into 1-day-old to 8-week-old calves generally resulted in leukopenia and fever. Of 6 colostrum-deprived calves inoculated before they received their first milk, 3 died; however, a comparable proportion (9/17) of uninoculated colostrum-deprived calves also died. In 4- to 8-week-old calves exposed to the virus, fever and leukopenia developed but less than half of the calves developed diarrhea and few died. None of the colostrum-fed, uninoculated calves died. Infection of the fetus in utero seemed to be of common occurrence, as judged by the finding of antibodies to one or more bovine enteroviruses in fetuses aborted at 4 months or more of gestation. The antibodies were believed to be of fetal origin. It was postulated that in utero infection may contribute to early death or lack of resistance of the newborn calf to bacterial infection.