CONSTRUCTION AND CHARACTERIZATION OF A REOVIRUS DOUBLE TEMPERATURE-SENSITIVE MUTANT

The infectious reovirus RNA system tvas used to construct a mutant wit h two temperature-sensitive (ts) lesions in genome segments M2 and S2, respectively. The double mutant is about 300 times more ts than eithe r of its parents, which are about 1,500 and 170 times more ts than the ir wild-type parent reovirus ST3 strain Dearing. At 39 degrees C the d ouble mutant is essentially unable to multiply In spite of its strikin g temperature sensitivity, the double mutant elicits the formation of significant amounts of neutralizing antibodies in newborn mice. Possib le mechanisms responsible for this are discussed, as is the significan ce of this double ts mutant in relation to current searches for safe a nd efficient vaccine strains.