This project is designed to cultivate directly in cell culture a variety of human and animal rotavirus strains from diverse geographical areas and populations in order to define antigenic differences and to identify and develop potential vaccine candidates. Over 80 strains of human rotaviruses have been cultivated in MA104 or AGMK cells. Four distinct serotypes of human rotavirus have been identified and compared with each other and with 12 animal rotavirus strains. Three distinct serotypes represented only by animal rotavirus strains were defined, but 6 animal rotaviruses were also found which are serotypically similar if not identical to human rotavirus belonging to serotype 3 or 4. Potential candidate vaccine strains of different serotypes have been grown either in primary or secondary African green monkey kidney or in diploid cells which are suitable for vaccine production, and these now can be evaluated further for safety and efficacy.