THE SEMLIKI-FOREST-VIRUS VECTOR INDUCES P53-INDEPENDENT APOPTOSIS

Three deletion mutants of the structural protein region of the Semliki Forest virus (SFV) genome, including one which encompassed all the vi ral structural protein genes, induced apoptosis in BHK cells at 48 h a fter transfection, as shown by DNA laddering and TUNEL staining, as di d the wild-type SFV4 RNA, A similar result was obtained for the SFV1 e xpression vector, which has a multicloning site inserted in place of t he structural protein genes. However, in cells transfected with viral RNA containing a deletion of the nsP2 gene, neither viral RNA synthesi s nor the induction of apoptosis occurred. Both SFV1 vector and wild-t ype SFV4 RNA induced apoptosis in human H358a lung carcinoma cells, wh ich have a homozygous deletion of the p53 gene. It is concluded that t he SFV vector encodes a function in the nonstructural coding region wh ich induces p53-independent apoptosis and is dependent on viral RNA sy nthesis.