The involvement of survival signaling pathways in rubella-virus induced apoptosis

Cooray, Samantha; Jin, Li; Best, Jennifer M

This increase in speed and magnitude of RV-induced apoptosis is more strikingly observed in Fig. 3B , which shows the number of dead floating cells by trypan exclusion staining in the culture supernatant fluid of RV infected and LY294002 treated cells. LY294002 treatment doubles (and at 84 hours p.i. triples) the number of floating cells produced in RV-infected cells. Increases in the number of apoptotic floating cells are statistically significant at 84 and 96 hours p.i. (P < 0.05). Fragmented DNA patterns can be seen at 72 hours p.i. with both RV and RV in the presence of LY294002 (Fig. 3C) . However, the interesting feature of these apoptotic ladders is that in RVinfected cells, a significant proportion of genomic DNA is still intact, whereas when RV-infected cells are also exposed to LY294002, the majority of the genomic DNA is fragmented. The morphological changes caused by RVinfection and LY294002 were examined by light microscopy ( Fig. 3D ). At 72 hours p.i. CPE and induction of apoptosis by RV can be clearly seen. RV-induced CPE is characterized in the earlier stages by clumps of apoptotic cells, surrounded by healthy cells. In the later stages the cell sheet is completely destroyed and the majority of cells have become apoptotic floaters [6] . In the presence of LY294002, RV-infected cells are almost all dead by 72 hours p.i., resembling the later stages of RV-induced CPE.