Efficacy of a 3C-like protease inhibitor in treating various forms of acquired feline infectious peritonitis

Pedersen, Niels C; Kim, Yunjeong; Liu, Hongwei; Galasiti Kankanamalage, Anushka C; Eckstrand, Chrissy; Groutas, William C; Bannasch, Michael; Meadows, Juliana M; Chang, Kyeong-Ok

Sequential ascites samples were collected from some of these same cats over the first 6-25 days of antiviral treatment and tested for levels of viral RNA by qRT-PCR. FIPV levels are frequently low or negative in blood from cats with FIP and are highest in cells from effusions. 10 Therefore, cells from ascites or pleural effusions were the most reliable source of FIPV RNA. Cats CT15, CT16 and CT17 had 955, 1699 and 2937 times higher levels of viral RNA, respectively, than CT02, which had the lowest virus load in effusion prior to treatment (Figure 7 ). Viral RNA levels decreased by up to 1,567,463-fold within 2 weeks compared with pretreatment values, except for cat CT16 (Figure 8 ), which had the second highest viral RNA levels prior to antiviral treatment among the 12 cats with effusion samples available for testing ( Figure 7 ). The failure of viral RNA levels of CT16 to rapidly decrease, along with severe lymphopenia, may explain why it did not respond to treatment. CT10 also had a somewhat slower drop in virus levels and relapsed twice after antiviral treatment. It is noteworthy that viral RNA levels in ascites cells from cats CT15, CT17 and CT18 decreased the fastest and were also among the five cats that went into a sustained disease remission. Whether this was a property of the individual FIPV isolates or the form and severity of the host's disease was not determined.