Figure 9.

Antibody neutralization assay against PCV2a. (A) Schematic representation of antibody neutralization assay against PCV2a. Serum samples collected from different groups of immunized mice were 2-fold serially diluted in MEM to the dilution ranging from 1:8 to 1:1024 and incubated with a predetermined amount of PCV2a (100 TCID₅₀) for 1 h at 37 °C. Subsequently, the virus–serum mixtures were added to PK-15 cells. The cells were incubated for 48 h, after which the infection was analyzed by immunofluorescence staining. The fluorescence spots were directly captured via Opera Phenix High-Content Screening System and counted via Columbus Server using the cell count function. The assay was conducted in technical duplicates. (B) Inhibition percentage of serially diluted sera against PCV2a viruses. Inhibition by each serum sample of groups 1 and 3 are shown in the two top panels with mean value at each dilution. Means with standard deviations of each group are shown (bottom panel). Asterisk (*) indicates a significant difference between the immunized group and the PBS control group (p < 0.05).