Superinfection of baculovirus-infected gypsy moth cells with the nuclear polyhedrosis viruses of Autographa californica and Lymantria dispar

Abstract

Abstract The ability of the multiple-embedded nuclear polyhedrosis viruses (NPVs) of Autographa californica (AcMNPV) or Lymantria dispar (LdMNPV) to replicate in either a permissive system, LdMNPV-infected gypsy moth cells, or a semipermissive system, AcMNPV-infected gypsy moth cells, upon superinfection, was studied. Inoculation of LdMNPV-infected cells with AcMNPV up to 8 h postinfection (p.i.) resulted in significantly reduced LdMNPV non-occluded virus (NOV) production, suggesting viral interference. In these same experiments, AcMNPV NOV production occurred with maximal titers at 48 h p.i. in cells superinfected by 6 h p.i. In the converse experiment, superinfection of AcMNPV-infected gypsy moth cells by LdMNPV during the early phases of replication (up to 8 h) resulted in the production of polyhedral inclusion bodies, unlike gypsy moth cells infected only with AcMNPV where virus particles are not produced. In both systems, DNA-DNA dot hybridizations detected simultaneous viral DNA replication of both viruses. Analysis of [35]methionine-labeled fractions from superinfected cells by SDS-polyacrylamide gel electrophoresis revealed polypeptides similar to those produced by AcMNPV and LdMNPV during solitary infections. These results suggest that both the primary and superinfecting viruses adsorbed, penetrated, and initiated macromolecular synthesis. Moreover, viral progeny were produced in the semipermissive system upon superinfection with LdMNPV during the early α phase of replication.