Characteristics of Single- and Double-Stranded RNA Synthesis by a Rotavirus SA-11 Mutant Thermosensitive in the RNA Polymerase Gene

MUNOZ, MARIANNE; RIOS, MARITZA; SPENCER, EUGENIO

INTERVIROLOGY

KARGER

Lugar: Basel; Año: 1995 vol. 38 p. 256 - 263

0300-5526

The phenotype of a rotavirus SA-11 mutant, ts C, which carries a mutation in the gene coding for the viral RNA polymerase was studied in vitro, ts C viral transcription proved to be sensitive to temperature in a different way to that previously described. Like the wild type, the ts C mutant has an optimum for in vitro transcription at 45°, but mRNA synthesis was inhibited at temperatures over 50°. This mutant also showed a higher resistance to transcriptional inhibition by nucleotide analogues than the wild-type strain. The in vitro minus-strand RNA synthesis catalysed by ts C particles indicates that the mutant does not exhibit the expected increased sensitivity to temperatures over 31° shown by the in vivo phenotype. As with plus-strand synthesis, the optimal temperature for the minus-strand synthesis assay was 45°, but for temperatures over 55°, the number of double-stranded RNA products was altered. Our results suggest that when in vitro plus- and minus-strand RNA synthesis in ts C and wild type are compared, the mutated VP1 motif affects both transcription and minus-strand synthesis, but in different ways. In infected cell cultures, the results also show that the phenotype associated with ts C seems to mainly affect the function of plus-strand RNA synthesis