Viral and host cellular transcription in Autographa californica nuclear polyhedrosis virus-infected gypsy moth cell lines

Abstract

Infection of two gypsy moth cell lines (IPLB-Ld652Y and IPLB-LdFB) by the Autographa californica multiple-enveloped nuclear polyhedrosis virus (AcMNPV) is characterized by extremely attenuated viral protein synthesis followed by a total arrest of all viral and cellular protein production. In this study, AcMNPV- and host cell-specific transcription were examined. Overall levels of viral RNAs in infected gypsy moth cells were, at most measured times, comparable to RNA levels from an infected cell line (TN-368) permissive for AcMNPV replication. Northern blot (RNA) analyses using viral and host gene-specific probes revealed predominantly normal-length virus- and cell-specific transcripts postinfection. Transport of viral RNAs from the nucleus to the cytoplasm and transcript stability in infected gypsy moth cells also appeared normal compared with similar parameters for AcMNPV-infected TN-368 cells. Host cellular and viral mRNAs extracted from gypsy moth and TN-368 cells at various times postinfection and translated in vitro yielded similar spectra of host and viral proteins. Treatment of infected gypsy moth cells with the DNA synthesis inhibitor aphidicolin eliminated the total protein synthesis shutoff in infected IPLB-LdFB cells but had no effect on protein synthesis inhibition in infected IPLB-Ld652Y cells. The apparent selective block in the translation of viral transcripts early in infection and the absence of normal translation or transcription of host cellular genes at later times is discussed.