CFMNPV BLOCKS ACMNPV-INDUCED APOPTOSIS IN A CONTINUOUS MIDGUT CELL-LINE

Morphological and molecular changes produced by Autographa californica nuclear polyhedrosis virus (AcMNPV) infection in a permissive cell li ne, IPLB-SF-21AE (SF-21), of Spodoptera frugiperda and a nonpermissive cell line, FPMI-CF-203 (CF-203), of Choristoneura fumiferana are desc ribed. CF-203 cells inoculated with AcMNPV showed a DNA ladder and mor phological 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-2 1 cells inoculated with AcMNPV and no apoptosis-like symptoms were obs erved. mRNA for the apoptosis suppressor gene p35 was detected 9 hr la ter in AcMNPV-inoculated CF-203 cells than in SF-21 cells. Only a trac e amount of mRNA for the AcMNPV-inhibitor of apoptosis homologue (Ac-i ap) gene and no mRNAs for the late genes, AcMNPV-polyhedrin (Ac-polh) and AcMNPV-p10 (Ac-p10), were detected in AcMNPV-inoculated CF-203 cel ls. Inoculation of CF-203 cells with CfMNPV at least 12 hr prior to in oculation with AcMNPV prevented apoptosis-like cell death, and mRNAs f or Ac-iap, Ac-polh, and Ac-p10 genes were expressed resulting in succe ssful virus replication and OB production. (C) 1996 Academic Press, In c.