Further genetic analysis of a temperature-sensitive mutant of cowpea mosaic virus

The two reciprocal hybrids of wild-type cowpea mosaic virus (Sb) and the temperature-sensitive mutant N168 were constructed. Symptoms of both hybrids differed from those of the parent strains in three differential hosts indicating that N168 carries mutations in both components and that symptoms result from interactions between components. The occurrence of one or more temperature-sensitive mutations in the middle-component RNA was confirmed. In vitro recombination of the hybrids yielded isolates indistinguishable from the parent strains.