Feline herpesvirus-1 (FHV-1) is a major pathogen of cats with worldwide distribution. Commercially available live vaccines against FHV-1 are widely used but their recognized serious drawback is the lack of complete attenuation of the virus resulting in the occurrence of vaccine induced clinical signs. The overall objective of the proposed research is to develop a recombinant DNA vaccine against FHV-1 that is safer and more immunogenic then existing products. During phase I a panel of monoclonal antibodies against the surface glycoproteins of FHV-1- will be developed and screened for antigenic specificity and virus neutralizing ability. These monoclonal antibodies are the essential tools for isolation of individual glycoproteins with affinity columns, mapping of the glycoprotein genes and screening of expression vector products, the major objectives of phase II. The value of this system as a model for human herpesvirus vaccine development comes from the fact that it allows definition of glycoprotein induced immunity in the natural host of the disease.