Infection of Spodoptera frugiperda cells with Autographa californica nuclear polyhedrosis virus : II. The viral DNA and the kinetics of its replication

Abstract

The kinetics of replication of Autographa californica nuclear polyhedrosis virus (AcNPV) DNA in Spodoptera frugiperda cells in culture were studied. Viral DNA replication started at about 5 hr postinfection, the rate of viral DNA replication reached a maximum at about 18 hr postinfection and thereafter decreased. Parental viral DNA could be detected within the first hour postinfection in the total intracellular DNA by the Southern technique. There was no evidence for the occurrence of AcNPV DNA sequences which became covalently linked to cellular DNA between 1 and 3 hr post-infection in the productive cycle. The AcNPV DNA appeared as a covalently closed circular molecule of about 92 × 10 6 daltons. The AcNPV DNA did not seem to be methylated, at least there were no 5′-C mCGG3′ sequences detectable in this DNA. Restriction enzyme analysis of viral DNA preparations derived from several single plaque isolates of AcNPV as well as of DNA from different virus stocks revealed a certain heterogeneity of the AcNPV DNA.