A total of 27 strains (positive rate=82%) were successfully isolated from fecal samples and showed positive in the PCR test. The specific CPE of CPV-2 in F81 cells was elongated and thinned cells with gaps between them(Figure 1). F81 cells incubated with CPV-2 emitted green fluorescence under the fluorescence microscope, indicating the reproduction and reproduction of CPV-2 in F81 cells.
Figure 1. CPV-2 isolation and direct immunofluorescent (DIF) assay results. (a) CPE of F81 cells incubated with CPV-2. (b) Normal F81 cell. (c) The DIF assay result of F81 cell incubated with CPV-2. (d) Negative control.
Amplification of VP2 Gene and GenotypeAnalysis
Full-length VP2 nucleotide sequences were amplified from 27 samples, which is 2293bp in length. After aligned with reference strains, extra sequences were cut off and simplified into 1755bp, namely the full VP2 gene. Table 1 provided the background information of CPV-2 strains isolated in this study.