Efficacy of an inactivated feline calicivirus (FCV) vaccine against challenge with United Kingdom field strains and its interaction with the FCV carrier state.

The efficacy of an inactivated vaccine derived from feline calicivirus (FCV) strain FS2 was assessed against challenge with three UK field strains of FCV. The mean clinical score, calculated on the number of signs recorded per day over 21 days after challenge, was lower for vaccinated cats when compared to unvaccinated animals though the difference was not statistically significant. All cats excreted FCV throughout the three weeks following challenge and there was no difference in the number of days of virus shedding during this period between vaccinated and unvaccinated animals. The development of FCV serum neutralising antibody titres following vaccination and challenge was recorded. In the second part of the study the ability of vaccinated and challenged cats to become FCV carriers and then infect susceptible in-contact animals was demonstrated.