3 FORMS OF AU-1 LIKE HUMAN ROTAVIRUSES DIFFERENTIATED BY THEIR OVERALL GENOMIC CONSTELLATION AND BY THE SEQUENCE OF THEIR VP8

Insight into the origin of human rotaviruses carrying the AU-1 VP4 all ele was gained by examining their genomic RNA constellation using RNA- RNA hybridization and by sequencing the VP8 portion (nucleotides 1-75 0) of their gene 4. AU-1 like viruses isolated in Israel from children attending outpatient clinics were classified into three sub-genogroup s based on RNA-RNA hybridization analysis: Subgenogroup 1 consists of two strains (Ro-5829 and Ro-5960) which belong to the AU-1 genogroup, since all their 11 segments hybridized to AU-1 segments. Subgenogroup 2 consists of one reassortant virus (Ro-5193) of which seven RNA segme nts hybridized to AU-1 segments and the remaining four segments hybrid ized to NCDV (bovine rotavirus). Subgenogroup 3 consists of four reass ortant viruses (Ro-6460, Ro-6584, Ro-6784 and Ro-7044) which had a com mon genome constellation: only four of their RNA segments hybridized t o AU-1 and the other seven segments hybridized to NCDV segments. Seque nce analysis of the VP8 gene also revealed. a three level pattern of homology with the AU-1 prototype and the local AU-1-like strains which was consistent with the overall genomic (RNA-RNA) constellation: Subg enogroup 1 had 98-98.1% homology with the AU-1 prototype; Subgenogroup 2 had 96.8% homology with the AU-1 prototype and 95.6-96.7% homology with Subgenogroup 1; Subgenogroup 3 had 95.3-95.6% homology with the p rototype AU-I and 93.4-94.3% homology with Subgenogroup 1. Possible ev olutionary pathways are discussed.