Fig. 1. Cytopathic effects (CPEs) of CAV type 2 (CAV-2) isolates in infected Vero cells (A) and normal Vero cells (B). Indirect immunofluorescence assay using monoclonal antibodies against CAV-1 (C and D) and CAV-2 (E and F). Vero cells infected with the APQA1601 isolate showed specific CPEs, and intranuclear fluorescence (E) was observed in Vero cells stained with the CAV-2 antibody. 200× (A-F).
Fig. 2. Growth curves of the APQA1601 strain at passage 10 according to the time of harvest from Vero and Madin-Darby canine kidney (MDCK) cells. The APQA1601 strain showed higher proliferation in MDCK cells than in Vero cells.
Fig. 3. Viral particles from the APQA1601 strain propagated in Vero cells. CAV-2 particles of 60–80 nm in diameter are visible in the nucleus and cytoplasm. Scale bars = 500 nm (A), 100 nm (B).
Fig. 5. Comparison of the full nucleotide sequences among four CAVs (A). A phylogenetic analysis based on the nucleotide sequences of the fiber genes from 11 adenoviral strains (B). The APQA1601 strain had the highest homology with the Toronto A26/61 strain isolated in Canada. The phylogenetic tree was constructed based on alignments of nucleotide sequences obtained using the neighborjoining method.
Fig. 4. Three primer sets targeting the F gene of the APQA1601 isolate were used for polymerase chain reaction (PCR). PCR products of the expected sizes confirmed the identification of the isolate as CAV-2.
Table 1. List of primers used for polymerase chain reaction analysis of canine adenovirus (CAV) type 2
Table 2. Hemagglutination activity of CAV isolates using red blood cells from several species