3.4 IFA and Electron microscopy observation
The presence of FPV in the cell culture fluids at the fifth passage
level was confirmed by PCR assay using the FPV speculative primer pair.
IFA results showed green fluorescence in infected CRFK cells probed with
an anti-FPV monoclonal antibody (Figure 4A), in contrast, there was no
fluorescence in normal CRFK cells (Figure 4B). The diameter of the
virion was approximately 20-25 nm which was observed under the electron
microscope and revealed no
envelope,
spherical shape, and the
icosahedral structure, and these were consistent with the structural
characteristics of panleukopenia virus (Figure 5).