Further characterization of the t-s mutant F207 of bluetongue virus.

Temperature-shift experiments verified that the t-s lesion of BTV mutant F207 is expressed late in the replication-cycle, that is, at a stage when all virus components have already been synthesized. All viral polypeptides were indeed found in the soluble but not in the particulate fraction of cytoplasmic extracts from infected cultures grown at the non-permissive temperature. This suggests that the t-s lesion could be a defect in one or both of the polypeptides P2 and P5, which are respectively reduced in amount and absent from the latter fraction. Alternatively, the lesion could be an inability of the core particle to bind these 2 outer capsid polypeptides.