Vaccinia virus-induced apoptosis in immature B lymphocytes: role of cellular Bcl-2

Apoptosis is a form of physiological cell death which can be initiated in r esponse to various stimuli including virus infections. We show that vaccini a virus (VV) infection induces apoptosis in an immature B lymphocyte line, WEHI-231. In these cells, several VV-specific proteins were synthesized dur ing the infection, bur neither virus production nor viral DNA synthesis wer e detected. The intracellular levels of the proto-oncogene Bcl-2, which eff ectively protects cells from programmed cell death, were found to be down-r egulated by the VV infection, suggesting that this down-regulation might be involved in the viral induction of apoptosis in WEHI-231 cells. Stable tra nsfectants overexpressing human Bcl-2 were shown to be resistant to the apo ptosis produced by the infection, a finding consistent with the proposed ro le for the down-regulation of endogenous Bcl-2 in W-induced apoptotic death . (C) 1998 Elsevier Science B.V. All rights reserved.