2.2 | Extraction of CPV genome
Fecal swabs were rinsed with 1ml sterile phosphate-buffered saline (PBS), and centrifuged at 12,000 × g and 4°C for 10 min, and the supernatants were stored at −80℃. The small intestinal tissue homogenates were clarified by centrifuging at 12,000×g and 4°C for 10 min to separate the supernatant. Then, 200 μL of supernatant from each sample was filtered through a 0.22 μm filter (Millipore, USA). The viral DNA was extracted from the supernatant of the treated samples by an AxyPrepTMviral DNA miniprep kit (Axygen Scientific, Tewksbury, MA, USA) according to the manufacturer’s instructions.