CfMNPV BlocksAcMNPV-Induced Apoptosis in a Continuous Midgut Cell Line

Abstract Morphological and molecular changes produced by Autographa californica nuclear polyhedrosis virus ( Ac MNPV) infection in a permissive cell line, IPLB-SF-21AE (SF-21), of Spodoptera frugiperda and a nonpermissive cell line, FPMI-CF-203 (CF-203), of Choristoneura fumiferana are described. CF-203 cells inoculated with Ac MNPV showed a DNA ladder and morphological changes such as plasma membrane granulation, blebbing, and nuclear fragmentation, which are characteristic of apoptosis. Typical virus replication and occlusion body (OB) production were seen in SF-21 cells inoculated with Ac MNPV and no apoptosis-like symptoms were observed. mRNA for the apoptosis suppressor gene p35 was detected 9 hr later in Ac MNPV-inoculated CF-203 cells than in SF-21 cells. Only a trace amount of mRNA for the Ac MNPV-inhibitor of apoptosis homologue ( Ac-iap ) gene and no mRNAs for the late genes, Ac MNPV-polyhedrin ( Ac-polh ) and Ac MNPV-p10 ( Ac-p10 ), were detected in Ac MNPV-inoculated CF-203 cells. Inoculation of CF-203 cells with Cf MNPV at least 12 hr prior to inoculation with Ac MNPV prevented apoptosis-like cell death, and mRNAs for Ac-iap, Ac-polh, and Ac-p10 genes were expressed resulting in successful virus replication and OB production.