PPIB and Pleural effusion: Inhibits cyclophilins and thereby blocks replication of FCoV in vitro [345,346]. Associated with a reduction in blood FCoV viral load in three cats with suspected FIP, and reduced pleural effusion FCoV viral load and volume in one cat that survived 264 days after presentation before dying (see supplementary data in Tanaka et al. 2015 [347]). Can lead to immunosuppression, depending on the cyclosporine A derivative.