Determination of Optimal Labeling pH for p30 and p72 Protein
The pH of the gold solution was adjusted to 4–9 using 0.1 mg/mL K2CO3 solution; an appropriate amount of protein (60 μg/mL of p30 and 9.6 μg/mL of p72) was then added to the gold solution. After standing for 2h at room temperature, the solution was centrifuged at 12,000 rpm for 30 min at 4 °C; the supernatant was collected and coated on an ELISA plate; reactivity to ASFV-positive serum was measured by indirect ELISA. Finally, the pH was taken as the abscissa, and the OD450 nm value was drawn as a scatter diagram to determine the optimum pH.