Rotavirus isolation and cultivation in the presence of trypsin

Abstract

Rotaviruses are generally difficult to isolate and culture in vitro; therefore, virus isolation was not used as a method of diagnosing this group of agents. The present report describes a simple procedure for isolating bovine rotaviruses directly from [calf] feces after pretreatment of fecal samples with trypsin. This procedure resulted in virus isolation from 5 of 5 samples that contained virus particles, as demonstrated by EM, and 4 of 7 samples where virus particles could be observed but were considered positive by the presence of immunofluorescent-staining cells in feces. Virus could not be isolated from normal feces. If the virus was not passaged in the presence of trypsin, the infectivity was gradually lost, but infectivity could be restored again if trypsin was added, resulting in increased virus spread and concomitant increase in virus yield. The application of this technique as a diagnostic tool for bovine and other rotaviruses is briefly discussed.