SELECTION OF ROTAVIRUS VP7 GENE IN THE GENETIC BACKGROUND OF SIMIAN ROTAVIRUS SA11 - IMPLICATIONS FOR ROTAVIRUS REASSORTANT VACCINE DEVELOPMENT

We previously reported that the VP7 gene from simian rotavirus SA11 wi th G-serotype 3(G3-VP7 gene) was preferentially selected in the geneti c background of SA11 compared with the G1- or G2-VP7 gene. In the pres ent study, selection of the G4-VP7 gene in competition with G1-, G2- o r G3-VP7 gene in the SA11 background was analyzed through mixed infect ion experiments using SA11 and SA11-human rotavirus single-VP7 gene-su bstitution reassortants with G-serotypes 1. 2, and 4 (G1-, G2- and G4- reassortant). In virus clones from coinfection of SA11 and G4-reassort ant. the frequency of G4 virus decreased to 7% at the 3rd passage and the G4 virus disappeared at the 10th passage, whereas the majority of the clones possessed G3 specificity. However, the predominance of eith er of the viruses coinfected was not observed in the mixed infection w ith G4-reassortant and G1- or G2-reassortant. Although growth kinetics of SA11 and G4-reassortant was similar, G4-reassortant showed signifi cantly smaller plaque size than SAIL. G1- and G2-reassortant did. Thes e results indicated that the G3-VP7 gene from SAIL might be preferenti ally selected in the SAIL genetic background compared with the G4-VP7 gene, and suggested that the introduction of a single G4-VP7 gene may affect growth characteristics of recipient virus SA11. These results t ogether with our previous findings suggested the significance of genet ic compatibility between recipient viral genes and foreign VP7 gene in the development of multivalent reassortant rotavirus vaccines.