Huang C, Hess J, Gill M et al.: A dual-strain feline calicivirus vaccine stimulates broader cross-neutralization antibodies than a single-strain vaccine and lessens clinical signs in vaccinated cats when challenged with a homologous feline calicivirus strain associated with virulent systemic disease, J Feline Med Surg 12:129, 2010.
Feline calicivirus (FCV) is generally associated with mild upper respiratory disease. In recent years, a more severe disease syndrome with high mortality has been linked to FCV infection. Viral mutations responsible for the different disease presentations have not been identified. In addition, these viruses differ in antigenicity, or how they appear to the immune system of the cat. This has an impact on the effectiveness of vaccines to induce protection against all strains of the virus. This report describes the ability of a vaccine containing two different strains of FCV to induce protection in vaccinated animals against many strains of the virus. The two strains used were a traditional FCV strain and a strain isolated from a case of virulent systemic disease (VSD). Serum from vaccinated cats was tested for protection (neutralization antibodies) against various FCV isolates. Immunity, as indicated by levels of serum neutralizing antibodies in vaccinated cats was tested against 37 European isolates of FCV as well as six VSD isolates from the United States. It is not clear as to whether these isolates were characterized genetically or antigenically; thus, their similarity or dissimilarity could not be assessed. This is important when assessing cross-protectiveness of a vaccine against different virus strains. Serum from cats vaccinated with both FCV strains neutralized more FCV isolates than that from cats vaccinated with a single FCV strain. Not surprisingly, cats vaccinated with the VSD-producing strain were protected against challenge with the same, virulent virus. The researchers conclude that this vaccine containing two strains is more effective than those containing a single strain. But given that the diversity of the strains against which the vaccine was tested was not described, this cannot be definitively stated. [MK]
Radford AD, Addie D, Belak S et al.: Feline calicivirus infection ABCD guidelines on prevention and management, J Feline Med Surg 11:556, 2009.