Macromolecular synthesis in cells infected by frog virus 3: I. Virus-specific protein synthesis and its regulation

Abstract

Heat-inactivated frog virus 3 inhibited protein synthesis in fathead minnow and baby hamster kidney cells but did not affect the replication of superinfecting infectious frog virus 3 in these cells. This method of controlling host-cell protein synthesis enabled us to identify 20 proteins induced by frog virus 3 infection. All detectable virus-specific proteins were synthesized within 2 hr after infection. Three viral structural proteins (VSP)—7, 9, and 13—were synthesized at maximum rates early in infection, and two others, VSP 5 and 11, reached their peak rate of synthesis late in infection. All structural and nonstructural proteins were made in the presence of cytosine arabinoside, an inhibitor of DNA synthesis. In the absence of viral DNA replication, the kinetics of synthesis of VSP 5 and 11 were similar to those during normal infection, but there was no reduction in the synthesis of VSP 7, 9, and 13 late in the infection. These results suggest that synthesis of all viral structural proteins is an early event in the FV 3 replication cycle, with progeny viral DNA required to regulate the synthesis of certain viral proteins.