EXPRESSION OF THE AUTOGRAPHA-CALIFORNICA NUCLEAR POLYHEDROSIS-VIRUS APOPTOTIC SUPPRESSOR GENE P35 IN NONPERMISSIVE SPODOPTERA-LITTORALIS CELLS

Apoptosis was postulated as the main barrier to replication of the Aut ographa californica nuclear polyhedrosis virus (AcMNPV) in a Spodopter a littoralis SL2 cell line (N, Chejanovsky and E, Gershburg, Virology 209:519-525, 1995), Thus, we hypothesized that the viral apoptotic sup pressor gene p35 is either poorly expressed or nonfunctional in AcMNPV -infected SL2 cells, These questions were addressed by first determini ng the steady-state levels of the p35 product, P35, in AcMNPV-infected SL2 cells, Indeed, very low levels of P35 were found in infected SL2 cells in comparison with those in SF9 cells, Overexpression of p35, in transient-transfection and recombinant-virus infection experiments, i nhibited actinomycin D-and AcMNPV-induced apoptosis, as determined by reduced cell blebbing and release of oligonucleosomes and increased ce ll viability of SL2, How ever, SL2 budded-virus (BV) titers of a recom binant AcMNPV which highly expressed p35 did not improve significantly , Also, injection of S. littoralis larvae with recombinant and wild-ty pe AcMNPV BVs showed similar 50% lethal doses, These data suggest that apoptosis is not the only impediment to AcMNPV replication in these n onpermissive S. littoralis cells, and probably in S, littoralis larvae , so p35 may not be the only host range determinant in this system.