Replication of Heliothis zea Nuclear Polyhedrosis Virus in Insect Cell Culture: Virus-induced and Structural Proteins

Abstract

The replication of Heliothis zea nuclear polyhedrosis virus was studied in the H. zea (IPLB-HZ-1075A) insect cell line. Infectious extracellular virus was first detected at 24 h post-infection (p.i.) and reached maximum titre of 1 .times. 107 p.f.u./ml at 90 h p.i. Viral DNA synthesis was detected by 14 h p.i. and increased exponentially until 32 h p.i. Using [35S]methionine pulse-labelling, 38 virus-induced proteins were identified, ranging in mol. wt. from 13K to 128K. Virus-induced protein synthesis was temporally regulated, with new proteins detected between 8 and 28 h p.i. Host cell protein synthesis continued throughout the virus replication cycle (48 h), although at gradually decreasing rates. Fifteen extracellular virus structural proteins were identified, and all but one comigrated with virus-induced proteins. Thirty-two structural proteins of tissue culture-derived, occluded virus were identified using silver staining procedures.