A new method for generating an immune response to prostate-specific antigen (I) involves: introducing a sufficient amount of a first pox virus (suipox virus, avipox virus, capri-pox virus, pigeon-pox virus, canary-pox virus, fowl-pox virus, swine-pox virus, or orthopox virus, especially vaccinia virus) vector to a host to stimulate an immune response, where the pox virus vector has at least one insertion site containing a DNA fragment encoding (I) operably linked to a promoter capable of expression in the host. At at least one periodic interval after introduction of the first pox virus vector contacting the host with extra (I) or a cytotoxic T-lymphocyte eliciting epitope of (I). The host is contacted with the extra (I) by introducing a second pox virus vector. A pharmaceutical composition of pox virus vector containing DNA encoding (I) is also new. Human (I)-specific cytotoxic T-lymphocytes produced by elicitation using (I) can be isolated from a human host and used in drug assays to map cytotoxic T-lymphocytes eliciting antigen epitopes or in adoptive immunotherapy.