EN
The aim of this study was to select swine rotavirus strains for the production of a live vaccine against rotaviral porcine diarrhoeas. The estimation of biological properties of strains was carried out under laboratory and field conditions. Seventeen swine field rotavirus strains were used for the investigations. The in vivo experiments were performed on colostrum-free piglets infected per os or intramuscularly with individual rotaviral strains. The virulence of strains was determined on the basis of their clinical condition after infection and the duration of shedder-state for 14 days after infection. In the in vitro estimation of strains, molecular biology methods were used by which extracts of viral RNA were examined by the polyacrylamide gel electrophoresis technique (PAGE). In the in vivo experiments a distinct difference in virulence of particular strains was demonstrated. A correlation between the virulence of particular strains was demonstrated. A correlation between the virulence of rotaviruses for colostrum-free piglets and the presence of rotaviral particles in faeces was found in electron microscopic examinations of faecal samples collected in the from infected sucklings. In some cases no viruses were detected in the faeces of infected piglets. Different electrophoretic mobility of particular genome RNA segments in examined strains was determined by electrophoresis. A rotavirus strain showing lack of virulence for colostrum-free piglets was selected for vaccine production. This strain differed considerably in the distribution of electrophoretic bands from the virulent reference OSU strain of swine rotavirus.