Genome heterogeneity of SA11 rotavirus due to reassortment with “O” agent

Derivatives of the rotavirus SA11-H96 strain, isolated in 1958 from an overtly healthy vervet monkey, have been used extensively to probe the viral life cycle. To gain insight into the phenotypic and genotypic differences among SA11 isolates, we sequenced the segmented double-stranded RNA genomes of SA11-H96 (P5B[2]:G3), two SA11-4F-like viruses (P6[1]:G3), two SA11-4F-like viruses with gene 5 rearrangements, and relevant segments of SA11 temperature-sensitive mutants and the “O” (Offal) agent (P6[1]:G8), a rotavirus isolated in 1965 from abattoir waste. This analysis indicates that the only complete genomic sequence previously reported for SA11 (Both) is instead that of a reassortant, originating like the SA11-4F-like viruses, from the introduction of an “O” agent gene into the SA11 genetic background. These results, combined with identification of mutations that correlate with altered growth properties and ts phenotype, emphasize the importance of considering segment origin and sequence variation in interpreting experimental outcomes with SA11 strains.