Fig. 1

Characterization of the monoclonal antibody specific to PCV3 Cap. a The MAb CCC160 was examined by western blotting analysis for its recognition of various purified recombinant proteins, including three recombinant PCV3 Cap proteins (Cap110–214, Cap110–160, and Cap161–214), a recombinant PCV2 Cap protein, and the pET32a carrier protein. Lane M: marker. b ST cells were transfected with pcDNA4c/PCV3 Cap and pcDNA4c/PCV2 Cap, respectively, and fixed at 48 h post-transfection, followed by immunofluorescence assay with the MAb CCC160 or the commercial MAb 36A9 which is specific to PCV2 Cap. c Epitope mapping of MAb CCC160 was performed using a competitive ELISA. The results were presented as the mean ± SD of triplicate experiments. Statistical significance was assessed with one-way ANOVA. **** P-value ≤ 0.0001 when compared to the cell control group. d Characterization of the specificity of MAb CCC160 with immunohistochemistry (IHC). H&E staining of lymph node tissues from PCV3⁺PCV2⁻ pigs and PCV3⁻PCV2⁺ pigs showed macrophage proliferation and mild lymphocyte depletion, whereas that from PCV3⁻PCV2⁻ pigs showed normal morphology. The IHC staining results showed that MAb CCC160 specifically recognized PCV3-infected tissues and a positive signal was observed (arrowed) but was not observed in normal or PCV2-infected tissues. The MAb 36A9 was used as a control to recognize PCV2-infected tissue