Sample collection
A total of 33 samples were collected from small animal clinics between 2018 and 2020. When the dogs were tested positive using Rapid CPV/CCV Ag Test Kit (Anigen, Korea) or showed some specific clinical symptoms, their fecal swabs will be mixed with normal saline and preserved in centrifuge tubes, which will be packed and mailed to our department and kept in a -80 °C refrigerator.
Virus isolation
The cell line used is the cat kidney F81 cell line. Added 1 mL PBS to each centrifuge tube and oscillated using an oscillator, then drew 500 μL liquid and filtered through a 0.22μm filter (Millipore, USA). At the same time, the cell suspension was prepared, which was digested by 0.05% pancreatin and maintained in Minimal Essential Medium (MEM, Gibco, USA) supplemented with 10% calf serum. The cell suspension was added to the culture flask and inoculated with CPV-2 with a proportion of 5%. The culture flask was kept in a CO2 incubator (MEMMERT, German). We harvested the virus when the cytopathic effect (CPE) was about 80%. The third passage of viruses was used for analysis.