Fig. 4
Experimental infection of cats with wild-type FFV and the FFV-Vif W/*1 chimera. Twelve SPF cats were separated into groups (n = 4 each) based on the inoculum type administered at day 0: naïve (N), wild-type FFV (WT), and chimeric FFV-Vif W/*1 (CH). Cats received 105 TCID50 of either wild-type or chimera. Animals were monitored daily for clinical signs of infection and blood samples were collected on days specified on the timeline above to characterize infection and immune responses. Samples were collected for baseline data on day -21. On day 53, cats in the CH group were re-inoculated with either undiluted wild-type FFV of 2.78 × 105 TCID50/ml (n = 2, referred to as CH1WT and CH2WT) or undiluted FFV-Vif W/*1 of 5.56 × 104 TCID50/ml (n = 2, referred to as CH3CH and CH4CH). Inoculation time points are marked by green stars. Animals were humanely euthanized and necropsied on day 176 p.i. (black X)