Cepharanthine: A promising natural compound against feline infectious peritonitis virus infection and associated inflammation.

Feline infectious peritonitis (FIP), a fatal disease in cats caused by feline infectious peritonitis virus (FIPV), has limited treatment options and lacks effective vaccines. Cepharanthine (CEP), a natural isoquinoline alkaloid, possesses many medicinal properties, including antiviral activities. However, the role of CEP in management of FIPV infection remains poorly understood. Here, we identified that CEP had a potent ability to inhibit FIPV infection in vitro. CEP significantly inhibited FIPV infection when administered at different times, with co-treatment showing the most significant inhibitory effect. Time-of-addition assays demonstrated that CEP exerted antiviral activity during the post-entry stages of the FIPV infection. We also verified that CEP inhibited FIPV infection not through affecting type I interferon expression, and it could decrease pro-inflammatory factors expression induced by FIPV infection. The combination of CEP and GS-441524 exhibited synergistic antiviral effects against FIPV infection. Our findings highlight the therapeutic potential of CEP for treatment of FIP.