[Comparative studies of plaque formation by strains of the mucosal disease-viral diarrhea virus (MD-VD)].

: Studied was the phenomenon of plaque forming with 2 local and 1 reference cytopathogenic strain of the MD-VD virus in cell cultures of calf kidney and testis. Studied was also the effect of trypsin in the preliminary treatment of the cell culture as well as the varying composition of the cover medium. The strains were found to form plaques that were varying in type and size. The ratio between the large and small plaques as well as the percent of plaques having unclear edges could serve as tentative strain features. It was established that at such experimental procedure the preliminary trypsin treatment of the cultures increased but slightly the plaque-forming capacity of the strains. The results obtained give grounds to the necessity of characterizing the vaccinal strains used through the type and ratio of the plaques formed.