Candidate vaccines based on the highly attenuated orthopoxvirus strain MVA are tested against various infectious and cancer diseases and, more profound, vaccines based on wildtype and recombinant viruses have been found safe and immunogenic in clinical trials. Compared to conventional vaccine strains, MVA lacks many functional genes for potentially important regulators of virus-host interactions. However, some gene functions responsible for counteraction of cellular antiviral pathways are still conserved in the genome of MVA and the inhibition of apoptosis seems to be one important mechanism, the virus is still able to interact with.rnrnVaccinia viruses encode several proteins which prevent the induction of virus-induced apoptosis. The vaccinia virus anti-apoptotic protein F1 was shown to counteract the activation of the mitochondrial pathway of apoptosis in a highly effective manner. Another vaccinia virus protein, N1, like F1 shows structural and functional similarity to members of the cellular anti-apoptotic bcl-2 family and was also shown to inhibit apoptosis. The vaccinia virus early protein E3 inhibits programmed cell death by binding to and sequestration of dsRNA molecules, normally inducing cellular antiviral pathways also driving the induction of apoptosis. All three anti-apoptotic genes were functionally analyzed during this work.rn