Autographa californica nuclear polyhedrosis virus-induced proteins in tissue culture

The multiplication of Autographa californica nuclear polyhedrosis virus was studied in Trichoplusia ni and Spodoptera frugiperda insect cell lines. Using pulse labeling, 18 viral-induced proteins were identified by polyacrylamide gel electrophoresis. Based on infectivity curves and protein synthesis studies, replication could be divided into four phases. During the early phase of infection, four viral-induced proteins with molecular weights of 45, 35, 34, and 31 thousand daltons could be detected. Maturation of the nonoccluded form of the virus and synthesis of 10 viral-induced proteins with molecular weights of 67, 61, 49, 41, 39, 26, 24, 22, 21, and 16 thousand daltons were first detected during the intermediate phase of replication, 10 to 16 hr postinoculation (p.i.). During the transitional phase from nonoccluded to occluded virus formation (16 to 24 hr p.i.), four additional viral-induced proteins could be detected with molecular weights of 33, 27, 15.7, and 15 thousand daltons. No additional viral-induced proteins were detected during the late phase of occluded virus formation. Post-translational cleavage was not detected in pulse-chase experiments. The addition of varying concentrations of NaCl did not selectively inhibit cellular protein synthesis.