The invention provides a gene transfer vector for inducing an immune response against Yersinia pestis in a mammal. The gene transfer vector comprises a nucleic acid sequence encoding an immunogenic portion of one or more proteins of Yersinia pestis and/or a nucleic acid sequence encoding a monoclonal antibody directed against Yersinia pestis. The invention further provides a method of producing an immune response against Yersinia pestis in a mammal comprising administration of the gene transfer vector to the mammal. The invention also provides a monoclonal antibody directed against the Virulence (V) antigen of Y. pestis, as well as a hybridoma cell line producing same and a nucleic acid sequence encoding same.