Identification of mutations in the genome of rotavirus SA11 temperature-sensitive mutants D, H, I and J by whole genome sequences analysis and assignment of tsI to gene 7 encoding NSP3.

The complete coding sequences of the four unassigned temperature-sensitive (ts) Baylor prototype rotavirus mutants (SA11ts D, H, I and J) were sequenced by deep sequencing double-stranded RNA using RNA-seq. Non-silent mutations were assigned to a specific mutant by Sanger sequencing RT-PCR products from each mutant. Mutations that led to amino acid changes were found in all genes except for genes 1 (VP1), 10 (NSP4) and 11 (NSP5/6). Based on these sequence analyses and earlier genetic analyses, the ts mutations in gene 7, which encodes the protein NSP3, were assigned to ts mutant groups I and H, and confirmed by an in vitro RNA-binding assay with recombinant proteins. In addition, ts mutations in gene 6 were assigned to tsJ. The presence of non-conservative mutations in two genes of two mutants (genes 4 and 2 in tsD and genes 3 and 7 in tsH) underscores the necessity of sequencing the whole genome of each rotavirus ts mutant prototype.