Abstract

The effect of replacement of gene Ii of rotavirus SA-II by a gene carrying a head to tail duplication obtained from a swine rotavirus strain was studied. The swine rotavirus strain with a duplicated gene (CC86) exhibits both a phenotype that allows to overgrow other viral strains when coinfected and an increased plaque size when plated in both CV-1 and MA-104 monkey kidney cells. Using reassortment methods the duplicated gene of the swine rotavirus was introduced into the SA-11 virus, replacing the regular gene II. The reasserted strain was characterized to find out the origin of each of the other viral gene segments. Based on electrophoretic mobilities segments 1, 2, 3, 5, 7, 8 and 10 were identified as of SA-11. The SA-11 origin of the segments 4, 6 and 9 was confirmed by neutralization with polyclonal and monoclonal antibodies and by ELISA. The results suggest that the new reassortant virus was a monoreassortant carrying SA-11 genes except the duplicated gene originated from the swine virus CC86. The ability to in vivo replicate and to synthesize viral proteins was identical in the reasserted virus and the parental strains. Sequence analysis indicates that the new phenotype does not originate in the duplication of gene Il but possibly from mutations in the coding region of NSP5 gene that may result in different phosphorylation patterns of the protein.