Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 9, 1999
Publication Date: N/A
Technical Abstract: Apoptosis is an important cellular response in limiting viral infections by specifically killing infected cells. The cell death process is irreversible following the activation of cytoplasmic cysteine proteases (caspases). The caspases are responsible for the degradation of cellular structural and repair proteins as well as activation of other degradative enzymes. Infection of Vero cells with San Miguel sea lion virus serotype 1 (SMSV1) resulted in the rounding and detachment of cells between 10 to 16 h post-infection (PI). Cleavage and activation of caspase 3 was detected by Western blotting at 8 h PI. Cleavage of the caspase 3 substrate protein, PARP, was also seen at 8 h PI. However, CPE formation in SMSV1-infected cells was not inhibited by the addition of the caspase 3 inhibitor Ac-DEVD-CMK in the medium following infection. Inhibitors of caspases 8 and 9 also had no effect. Mitochondrial changes (swollen membranes) were visible by electron microscopy at 8 h PI and were pronounced by 8 h PI. Mitochondrial damage was probably accelerated by the cleavage of the cell death antagonist, Bcl-XL, presumably by caspase 3 beginning at 8 h PI. These data show that caspase 3 is activated and plays a role late in apoptosis but does not initiate CPE formation and cell death.