Persistent feline coronavirus infection in a cat with cardiac and gastrointestinal signs

Feline coronavirus infection causes feline infectious peritonitis in a subset of cats, but can also result in persistent infection. The tissue reservoirs of feline coronavirus and the role of viral persistence in pathogenesis are poorly understood. This study aimed to identify sites of feline coronavirus persistence in a naturally infected cat, identify disease correlates and characterise within-host viral evolution. The study followed a 5-year-old Bengal cat for 6 years and collected non-invasive samples, including faeces and conjunctival, oropharyngeal and saliva swabs. At 11-years-old, the patient was euthanised as a result of respiratory distress, and tissue samples were collected. The authors used hybridisation capture and next-generation sequencing methodologies focused on the feline coronavirus S gene, along with RNA in-situ hybridisation. During the study, the patient was diagnosed with inflammatory bowel disease, alimentary small cell lymphoma, chronic rhinitis and mitral valve regurgitation. Feline coronavirus was detected in the nasal cavity, intestine, faeces and conjunctiva in 2017, and in the intestine, faeces and heart in 2022. Sequence analysis showed that the virus adapted to tissue reservoirs over time. This study identifies potential feline coronavirus reservoirs. The relationship of persistent feline coronavirus infection to chronic conditions warrants further investigation.