Selected and point mutated BPV genes will be subcloned into the Venezuelan Equine Encephalitis Virus Replicon Particles (VRP). Five horse will be immunized with these VRP’s and cellular immune response will be determined. The prophylactic effect of the vaccine will be determined after inoculation of these immunized animals with BPV-1 plasmid DNA. The therapeutic effect will be evaluated on 5 horses with naturally occurring equine sarcoids.