Development of a colloidal gold immunochromatographic assay strip using monoclonal antibody for rapid detection of porcine deltacoronavirus

Figure 1. The schematic representation of the GICA strip. (A) The strip included three pads (sample, conjugate and absorbent), an NC membrane, and a PVC plate. The conjugate pad contained the dried gold-labeled mAb-32#, which provided an easily visible red color. There were two lines on the NC membrane: the control line and the test line. The test line contained mAb-33#. The control line contained the goat anti-mouse IgG antibody. (B) The detecting principle of the GICA strip.

Figure 2. Characterization of mAb 32# and 33# by western blot. (A) mAb-32#; (B) mAb-33#. M-MW markers, 1-the purified rPDCoV-N protein, 2-the whole cell lysate without induction.

Figure 3. IFA analysis of mAb 32# and 33#. Both antibodies recognized the nucleocapsid protein in PDCoV-infected LLC-PK1 cells. The uninfected LLC-PK1 cells were used as a negative control.

Figure 4. Sensitivity of the GICA strip for detecting PDCoV. Different virus titers of PDCoV CZ2020 strain were detected by the strip. PBS and DMEM were used as the negative control.

Figure 5. Sensitivity of the GICA strip for detecting rPDCoV-N protein. Different concentrations of the protein (5.0, 1.0, 0.5, 0.25, 0.125, 0.0625 and 0.0313 μg/ml) were detected by the strip. PBS was used as the negative control (NC).

Figure 6. Specificity of the GICA strip. PDCoV cell culture supernatant as a positive control (+), LLC-PK1 cells as negative control (−), PEDV, TGEV, PoRV, PRRSV, PCV2, CSFV and PRV were tested with the strip.