Pathogenicity and vaccine efficacy of a thymidine kinase-deficient mutant of feline herpesvirus type 1 in cats

Abstract

We constructed a recombinant feline herpesvirus type 1 (FHV-1) which was deleted in a defined region (450 bp) within the thymidine kinase (TK) gene (C7301 dlTK) [Yokoyama et al. (1995) J Vet Med Sci 57: 709-714]. In this report, we carried out two experiments to assess the pathogenicity and vaccine efficacy of the recombinant C7301J/TK in cats. The first experiment showed that, following multiple inoculation of the recombinant C730WITK by intraocular, intranasal and oral routes, the virus was sufficiently attenuated in cats, although a high titer of the virus was recovered from target organs (eye, nose, and mouth). In the second experiment, two intramuscular vaccinations with the recombinant C7301dlTK protected cats to a significant degree against subsequent challenge with the parent FHV-1 strain C7301 at 4 weeks after the last vaccination. These results demonstrate that the recombinant C730WITK is effective as a live attenuated vaccine with a clear genetic marker. © Springer-Verlag 1996.