2.5 Virus isolation
Samples were collected from the spleen of dead lion cub from a park in Zheng zhou Province, China. Samples were tested by a PCR assay as described previously (Wu et al., 2015). FPV-positive samples were dissolved in phosphate-buffered saline (PBS) and then homogenized with a vortex. The samples were then centrifuged at 5000g for 5 min at 4 °C. Next, the supernatants were filtered using a 0.22 μm microporous filtering film. The filtered supernatants were inoculated into CRFK. Cell cultures were observed every 6 h for a cytopathic effect (CPE).