Fig 4.

SPPV14 can functionally replace F1L during vaccinia virus infection. (A to C) SPPV14 inhibits Bak activation during vaccinia virus infection. Wild-type (A), Bax/Bak-doubly deficient (B), or Bcl-2-overexpressing (C) Jurkat cells were mock infected or infected with VVEGFP, VVΔF1L, or VVΔF1L-FLAG-SPPV14 (F1L-deficient virus expressing FLAG-tagged SPPV14) vaccinia virus. Bak activation was detected 6 h later by flow cytometric analyses of cells stained with the conformation-specific anti-Bak Ab-1 antibody (28). Positive-control mock-infected cells were treated with the broad-spectrum kinase inhibitor staurosporine (+STS) (A, a), known to induce apoptosis in many cell types. The bars mark the populations that contained activated Bak. Experiments were performed in triplicate. Fractions of Bak-activated cells are given as percentages.