Feline calicivirus (FCV) is a small, unenveloped, single-stranded RNA virus that can cause feline upper respiratory tract disease (URTD). In order to understand some information about FCV infection in stray cats (not vaccinated), 145 oral/nasal swabs were randomly collected from different areas in China between 2014 and 2016. A FCV strain (named CH-JL4) was isolated and identified through PCR detection, cell culture, immunofluorescence assay (IFA), electron microscopy observation. Complete gene sequencing and phylogenetic analysis showed that it was 7709 nucleotides (nt) in length, excluding the poly (A) tail, and was genetically similar to other field FCV strains such as the HRB-SS strain (accession no. KM016908). All cats that were experimentally infected developed the typical clinical signs of FCV. However, the lung histology of the dying cats showed pulmonary congestion and hemorrhage, a small amount of fibrin exudation in the alveoli, shedding of alveolar epithelial cells, a small number of scattered neutrophils and oozing of red blood cells. The results indicated that virulent FCV infection in stray cat in China still existed. These results were beneficial for understanding the epidemic and pathogenicity in stray cats.

Key words: Feline calicivirus, Identification, Isolation, Pathogenicity