FIG. 4.

Strain NU14 induces cytochrome c release, and caspase 3 activity is blocked by Bcl_XL. (A) TEU-1 cultures were infected with strain NU14 at an initial MOI of 250 for 2.5 h in the presence or absence of 25 mM methyl α-d-mannopyranoside (Mann). S-100 extracts were prepared, and supernatants were analyzed for cytosolic cytochrome c by ELISA. Strain NU14 induced significant accumulation of cytosolic cytochrome c (P < 0.01) that was blocked by methyl α-d-mannopyranoside (P < 0.01 relative to NU14 treatment alone) and not observed for untreated cultures. Immunoblotting detected VDAC protein in S-100 pellets (P) but not in S-100 soluble fractions (S). Data are representative of duplicate experiments. (B) TEU-1 cultures were infected with adenoviruses encoding luciferase (AdLuc) or Bcl_XL (AdBcl_XL). The following day, cultures were infected with strain NU14, and then caspase 3 activity was quantified by DEVD-AFC cleavage. Strain NU14 induced caspase 3 activity that was not induced by the adenoviruses. Adenovirus encoding Bcl_XL inhibited NU14-induced caspase 3 activity, whereas adenovirus encoding luciferase did not. Data are representative of triplicate experiments.