THE WILD-TYPE AUTOGRAPHA-CALIFORNICA NUCLEAR POLYHEDROSIS-VIRUS INDUCES APOPTOSIS OF SPODOPTERA-LITTORALIS CELLS

Spodoptera littoralis cells infected with the Autographa californica m ultiple nuclear polyhedrosis virus (AcMNPV) yielded significantly towe r budded virus titers than Spodoptera frugiperda-infected cells and pr oduced very low levels of polyhedrin. Relative to AcMNPV-infected S. f rugiperda SF9 cells viral DNA replication was severely reduced in Spod optera littoralis SL2 cells. Microscopic examination of SL2-infected c ells revealed progressive cell blebbing starting at 6-8 hr postinfecti on and culminating in total cell destruction at 24 hr postinfection. T he data suggested that AcMNPV-infected SL2 cells undergo apoptosis. Th e occurrence of an active apoptotic process in the infected cells was confirmed by: (1) observation of fragmentation of the cell nuclei stai ned with the specific fluorescent dye DAPI (4',6'-diamidino-2-phenylin dole) and (2) the presence of low-molecular-weight DNA oligomers. Neit her SL2 cells infected with S. littoralis nuclear polyhedrosis virus ( SINPV) nor SF9 cells infected with AcMNPV, respectively, showed nuclea r fragmentation or oligonucleosomal ladder formation. (C) 1995 Academi c Press, Inc.