Studies with a Cold-Recombinant A/Victoria/3/7S (H3N2) Virus. I. Biologic, Genetic, and Biochemical Characterization

Abstract

A cold-recombinant virus, CR 22, was derived from an attenuated cold-adapted parent strain, AIAnn Arbor/6/60 (H2N2), and a wild-type parent strain, A/Victoria/3/75 (H3N2). Antigenic analysis showed that CR 22 possesses the hemagglutinin and neuraminidase surface antigens derived from the A/Victoria/3/75 (H3N2) parent. From studies of virus-induced polypeptides using polyacrylamide gel electrophoresis, it was deduced that a polymerase protein, PI, is coded for by an RNA segment derived from the wild-type parent; all other genetic elements are derived from the attenuated parent. The attenuated parent and the recombinant CR 22 both possess temperature-sensitive (ts) lesions, evident by restriction of multiplication in fertile chicken eggs or in MadinDarby canine kidney cell cultures at ⩾38 C. Genetic analysis of CR 22 by complementation tests using Hong Kong and Wilson Smith neurotropic ts mutants gave evidence for a ts lesion in the genetic elements coding for complementary RNA.