A NEW SEROTYPE OF THE OUTER CAPSID PROTEIN-VP4 SHARED BY AN UNUSUAL HUMAN ROTAVIRUS STRAIN-RO1845 AND CANINE ROTAVIRUSES

The VP4 protein of human rotavirus (HRV) strain Ro1845 and canine rota virus strains K9 and CU-1 exhibited greater than 98% amino acid identi ty within their group, but showed less identity with VP4 proteins of o ther HRV and animal rotavirus strains, the simian rotavirus strain RRV VP4 being most similar to them (90% amino acid identity). To exclude the possibility that these three strains were members of the RRV VP4 s erotype P3, neutralization studies were performed using antisera to re assortant viruses containing the VP4 gene from each of Ro1845, CU-1 an d RRV. The result established close antigenic similarity among the VP4 proteins of Ro1845. K9 and CU-1 and revealed only a marginal degree o f similarity between the VP4 proteins of these three strains and that of strain RRV. These sequence and serological data suggest that the VP 4 proteins of Ro1845, K9 and CU-1 represent a new P serotype which we propose to assign P13.