IN-VIVO PROPERTIES OF A FELINE HERPESVIRUS TYPE-1 MUTANT CARRYING A LACZ INSERTION AT THE GI LOCUS OF THE UNIQUE SHORT SEGMENT

The major cause of upper respiratory tract disease in cats is the feli ne herpesvirus type I (FHV-1). FHV-1 replicates predominantly in the m ucosal epithelium of the oral and nasal cavities, local immunity shoul d therefore be the key target for vaccine development. Recombinant DNA technology enables accurate manipulation of the genetic content of th e FHV-1 genome, hopefully resulting in a next generation of safe vacci ne strains that can be used intranasally in cats. Integration of a rep orter gene into the glycoprotein I (gI) homologous gene of FHV-1, resu lted in strain C4-1-4-1 which displayed reduced replication not only i n cell culture but also in the respiratory tract of infected cats. Oro nasal application of strain C4-1-4-1 caused less severe clinical signs than local administration of the parent virus. In addition, oronasall y vaccinated cats were better protected against the clinical signs of a challenge infection than cats vaccinated subcutaneously.