Four eight-week-old cats, shown to be free from feline calicivirus, feline herpesvirus and Chlamydia psittaci were challenged with an aerosol of Bordetella bronchiseptica. Within five days the cats developed signs of respiratory disease, characterised by nasal discharge, sneezing, spontaneous or induced coughing and dry or wet rales at auscultation. These signs were present for about 10 days, after which they began to resolve. To test the protective capacity of an experimental fimbrial antigen-based subunit vaccine, 10 kittens were vaccinated twice, with two weeks between the vaccinations, and five kittens were left unvaccinated. Two weeks after the booster the 15 kittens were challenged with an aerosol of B bronchiseptica as the sole pathogen. On the day of challenge the vaccinated kittens had a mean bordetella antibody titre of 2(9.5) whereas the control cats remained seronegative (titre < 2(2)). The control cats developed signs of respiratory disease after challenge, whereas the vaccinated cats were almost completely protected. The degrees of protection against rhinitis, sneezing, spontaneous or induced coughing, and dry or wet rales at auscultation were 100 per cent, 95 per cent, 95 per cent and 100 per cent, respectively. Furthermore, the vaccinated kittens cleared the challenge bacteria more quickly than the controls, resulting in a reduction of 80 per cent on days 15 and 18 after challenge and a reduction of 99 per cent on days 22 and 29 after challenge. The results show that B bronchiseptica can act as a primary pathogen in cats and that a vaccine containing the fimbrial antigen induces a protective immune response.

Nobivac Tricat, a lyophilised trivalent modified live attenuated vaccine is routinely used to protect cats against three commonly diagnosed feline viral pathogens namely herpesvirus, calicivirus and panleukopenia virus. The recognition of feline leukaemia virus (FeLV) as an important viral pathogen has prompted the development of an efficacious liquid recombinant subunit FeLV vaccine (p45 envelope protein). Lyophilised Tricat vaccine was dissolved in the liquid FeLV vaccine and no detectable deleterious effect on the titre of any of the live virus components was observed after 2h incubation. In vivo studies where the vaccines were mixed in the same syringe prior to inoculation showed no alteration to the safety profile assessed by repeat and overdose studies. Serological comparisons of the modified live viral antibody titres showed no evidence of reduced responses following administration of the mixed products. Challenge studies using pathogenic herpesvirus and FeLV revealed no difference in the degree of clinical protection. This paper shows that neither safety nor efficacy is adversely affected as a result of mixing the two vaccines.