Suppression of apoptotic and necrotic cell death by poliovirus

To determine an antiapoptotic activity of poliovirus type 1 (PV-1), we exam ined the effect of PV-1 infection on apoptosis that was induced in HEp-2 ce lls by the treatment with I M sorbitol. The virus did not induce apoptosis in the infected cells and could suppress both the fragmentation of chromoso mal DNA and morphological cell and cell nuclei changes in the sorbitol-trea ted cells, indicating that PV-1 induces an antiapoptotic state. Comparison of the kinetics showed that this ability of the virus appeared in the infec ted cells at the time of progeny virus formation (maturation step of virus multiplication). Simultaneously with this antiapoptotic activity, PV-1 infe ction also suppressed non-apoptotic cell death induced by sodium chloride. Electron microscopic observation revealed that the cells killed by the sodi um chloride treatment had undergone liquefactive necrosis, indicating that PV-1 can inhibit both apoptosis and necrosis. In addition, PV-1 can grow in the apoptotic cells, although the virus yield was reduced to a quarter of the yield in normal cells.