Detection and Characterization of Feline Calicivirus Associated with Paw and Mouth Disease

Simple Summary Feline calicivirus (FCV) is a common viral pathogen affecting domestic cats, which is responsible for diverse clinical presentations, commonly including upper respiratory tract signs, oral ulcerations, and a fever. In addition, FCV infection can be associated with severe pneumonia, lameness, and virulent systemic disease. In this study, we clinically and pathologically describe a rare case of FCV-associated paw and mouth disease in a febrile household cat. The FCV strains detected in the animal and in an overtly healthy cohabiting cat were analyzed to assess the phenotype and antigenic properties. Feline calicivirus (FCV) infection in cats can led to several diverse clinical presentations, ranging from mild upper respiratory signs to virulent systemic disease. Herein, we report a paw and mouth disease case in a 7-year-old household cat due to an FCV infection. An asymptomatic cat living in the same household was also infected with FCV. Clinical and pathological investigations were combined with the molecular and phenotypical characterization of the FCV strains. The RNA of the FCV was detected using qualitative and quantitative reverse transcription (RT)-PCR assays, and FCV antigen was confirmed by immunohistochemistry. After the whole genome analysis, the strains detected in the two cats appeared to be genetically diverse from FCVs previously detected in association with paw and mouth disease and with virulent systemic disease. Interestingly, the isolates obtained in this study were resistant to low pH conditions and slightly susceptible to bile salts, but they were susceptible to a trypsin treatment, revealing a phenotype pattern that is different from that which has been observed for respiratory FCVs.