We have discovered that by using a recombinant viral vector, preferably a pox virus vector having at least one insertion site containing a DNA segment encoding prostate-specific antigen (PSA), operably linked to a promoter capable of expression in the host, a specific humoral and cellular immune response to PSA can be generated. The method preferably comprises introducing a sufficient amount of the recombinant pox virus vector into a host to stimulate the immune response, and contacting the host with additional PSA at periodic intervals thereafter. The additional PSA may be added by using a second pox virus vector from a different pox genus. In another embodiment, additional PSA can be added by contacting the host with PSA by a variety of other methods, including in one preferred embodiment adding PSA. The PSA may be formulated with an adjuvant or in a liposomal formulation.