Feline coronavirus-associated uveitis: The eye as a gateway to systemic spread and feline infectious peritonitis?

Feline coronavirus (FCoV) is a virus endemic in cat populations. Specific genomic mutations give it a strong tropism for macrophages, allowing systemic infection and the development of a disease known as feline infectious peritonitis. This disease takes various clinical presentations, and can manifest as uveitis. Two mutations in the spike protein have been identified as possibly associated with FIP: mutations M1058L and S1060A. 193 clinical samples of aqueous humor were collected, all PCR-positive for feline coronavirus. Samples were taken either from cats with a clinical picture compatible with an ocular form of FIP (with uveitis and general clinical signs), or from cats with uveitis only. We sequenced the region of the S gene coding for positions 1058 and 1060 for 77 samples. The aim of the study was to determine whether viruses from cats with clinical signs compatible with FIP were more likely to harbor the M1058L and S1060A mutations. Our results confirm that these mutations are associated with severe disease, and also show that ocular samples from cats with uveitis alone are more likely to contain FECV.