Pustular calicivirus dermatitis on the abdomen of two cats following routine ovariectomy

Multiple Correspondence Analysis on Amino Acid Properties within the Variable Region of the Capsid Protein Shows Differences between Classical and Virulent Systemic Feline Calicivirus Strains

Feline calicivirus (FCV) is a widespread and highly prevalent pathogen of domestic cats, responsible for mild upper respiratory tract disease. Outbreaks of severe virulent systemic disease (VSD) associated with FCV infection have been reported worldwide. VSD FCV strains have a broader tropism and cause a systemic vascular compromise. Despite clear differences in the pathogenesis of VSD and oral respiratory infections, attempts to identify specific molecular markers of VSD strains on the major capsid protein VP1 have failed. Region E of VP1 is responsible for the interaction with the cell receptor Junctional Adhesion Molecule JAM-1 (FeJAM-1) and with VP2 minor capsid protein during the entry of the virus. We carried out an original analysis on the sequences from region E of VSD and classical strains. A Multiple Correspondence Analysis was performed on a Boolean matrix built by coding sequences on the basis of their amino acid properties. For the first time, this approach was able to differentiate VSD and classical FCV. Seven remarkable residue positions were shown to be statistically significant for pathotype differentiation, mainly located in the N-terminal hypervariable part of region E. As structural analysis suggested an interaction of these residues with FeJAM-1 or VP2, post-binding events, and specific conformational changes may explain the difference of pathogenesis between pathotypes.

Intranasal immunization with inactivated feline calicivirus particles confers robust protection against homologous virus and suppression against heterologous virus in cats

The protective efficacy of intranasal (IN) administration of inactivated feline calicivirus (FCV) vaccine against homologous or heterologous FCV infection was investigated. Groups of cats immunized with the experimental inactivated, non-adjuvanted FCV vaccine via either the IN or subcutaneous (SC) route were exposed to homologous or highly heterologous FCV. Both the IN and SC immunization protocols established robust protection against homologous FCV infection. Although neither immunization regimen conferred protection against the heterologous strain, clinical scores and virus titres of oral swabs were lower in cats in the IN group compared to those in the SC group, accompanying a faster neutralizing antibody response against the heterologous virus in cats in the IN group. The IN group secreted more IgA specific to FCV proteins in oral washes (lavage fluids from the oral cavity) than the SC group. IN immunization with an inactivated whole FCV particle, which protects cats from homologous virus exposure and shortens the period of heterologous virus shedding, may serve as a better platform for anti-FCV vaccine.

A nosocomial outbreak of feline calicivirus associated virulent systemic disease in France

This report describes a nosocomial outbreak of feline calicivirus (FCV) associated virulent systemic disease (VSD) in a French veterinary teaching hospital in 2005. The outbreak started in March and resolved within 1 month. Signs, clinical course, clinicopathological findings and lesions were typical of FCV-induced VSD. FCV infection was confirmed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Among the eight infected cats, two had to be euthanased, three died, and three recovered after medical treatment. Virus could not be confined inside the animal hospital and on two occasions, students' own cats became infected. Subsequent genetic sequencing studies confirmed that the eight cats were infected with the same strain of virus, and that it was distinct from those involved in the US and UK outbreaks of VSD. Virulence and viral excretion patterns of the isolated strain were further characterised by experimental infection.

Molecular virology of feline calicivirus

Caliciviridae are small, nonenveloped, positive-stranded RNA viruses. Much of our understanding of the molecular biology of the caliciviruses has come from the study of the naturally occurring animal caliciviruses. In particular, many studies have focused on the molecular virology of feline calicivirus (FCV), which reflects its importance as a natural pathogen of cats. FCVs demonstrate a remarkable capacity for high genetic, antigenic, and clinical diversity; "outbreak" vaccine resistant strains occur frequently. This article updates the reader on the current status of clinical behavior and pathogenesis of FCV.