ANALYSIS OF GENE SELECTION IN REASSORTANT FORMATION BETWEEN CANINE ROTAVIRUS K9 AND HUMAN ROTAVIRUSES WITH DIFFERENT ANTIGENIC SPECIFICITIES

A number of antigenic mosaic reassortants which have neutralization pr oteins VP4 and VP7 derived from different parental strains were analys ed in order to study gene selection in reassortant formation between a nimal human rotaviruses (HRV). These reassortants were isolated from m ixed infection of MA-104 cells with canine rotavirus strain K9 (subgro up I and G serotype 3) and HRV strains (with subgroup I or II antigen and G serotype 1-4, 9 or 12 antigen), through repeated selections with anti-VP4 and anti-VP7 neutralizing monoclonal antibodies directed spe cifically at HRV and K9, respectively. By serological and genomic anal yses, all the isolated clones were found to be antigenic mosaic reasso rtants possessing VP4 of K9 and VP7 of HRV. In the reassortants betwee n strain K9 and one of the six strains of subgroup II HRV, a single or a few genotypes with particular constellations of RNA segments were p redominant, with only a few RNA segments including gene 4 (encoding VP 4) being derived from K9. In contrast, in the reassortants between str ain K9 and any one of the subgroup I HRV, more than nine different gen otypes were identified and various RNA segments, except for segments 8 and 10, were derived from K9. These findings indicated that the RNA s egments of K9 might be reassorted more readily with those of subgroup I HRV than with those of subgroup II HRV, suggesting the possible exis tence of functional mechanisms which determine the extent of diversity of genome selection depending on the pairs of parent strains in the r eassortant formation.