The reassortment of viral genome segments has been reported to occur during coinfection of cultured cells with two different rotaviruses. Further, epidemiologic findings suggesting that genetic reassortment of viral RNAs may account for an antigenic shift in rotavirus in nature have also been accumulated. In the present study a reassortant virus, C148, was selected from fifty-one progeny virus clones obtained under an antibody pressure from a mixed infection of MA104 cells with human rotavirus serotype 3 (YO) and serotype 4 (Hochi) strains. Antigenic characterization and genotype analysis by polyacrylamide gel electrophoresis concluded that C148 virus possessed a mosaic antigenicity defined by two serotype-specific viral proteins (VP), i. e. the serotype 4-specific VP3 and the serotype 3-specific VP7. While the reassortant C148 was judged to belong to serotype 3 on the basis of its preferential neutralizability by serotype 3 antiserum, the antiserum prepared against C148 equally neutralized both serotype 3 and 4 viruses. These results seem to further support the possible emergence of a genetic reassortant in nature between human rotaviruses beloneinu to different serotypes
