Immunofluorescent cell assay of neonatal calf diarrhea virus.

A reliable plaque assay procedure has not yet been described for the neonatal calf diarrhea virus. Therefore, a previously developed immunofluorescent cell counting procedure was adapted to assay this virus. Adsorption of the virus to bovine kidney cells plateaued at 60 minutes. The optimal staining time was between 20 and 24 hours postinfection. Infected cells begun releasing from the coverslips if the cultures were incubated longer than 24 hours. This procedure has proven successful with virus grown in cell culture as well as virus present in fecal samples.