Fig. 2.

Detection of specific anti-GLU and anti-KT3 tag antibodies, as well as anti-PCV2 neutralizing antibodies, in specific-pathogen-free pigs infected with chimeric PCV1-2 containing the inserted KT3 or GLU epitope. Specific antibody responses were examined in the sera of pigs infected with PCV1-2 (■), PCV1-2-KT3 (●), PCV1-2-GLU (▵), or PBS (○) using three different ELISAs, (A) a PCV2 capsid-specific ELISA, (B) a KT3 tag-specific ELISA, and (C) a GLU tag-specific ELISA. The mean OD₄₅₀ ± the standard error of the mean is plotted for each treatment group throughout the experiment, with an asterisk indicating significant differences on that day. Treatments with different letters have statistically significant differences on that day. Statistical comparison was performed using repeated-measures analysis of variance, with the slice option of the Glimmix procedure, followed by Tukey's procedure for multiple comparisons. Statistical significance was set to alpha = 0.05. All analyses were performed using commercially available software (SAS version 9.2; SAS, Cary, NC). The dotted horizontal line indicates the cutoff of each assay. (D) PCV2-specific neutralizing antibodies (Ab) detected in sera of infected pigs at 42 dpi. Serum samples from each pig were tested for specific anti-PCV2a and anti-PCV2b neutralizing activity. Black bars represent PCV1-2, open bars represent PCV1-2-KT3, and shaded gray bars represent PCV1-2-GLU. The mean percentage of virus neutralization for each treatment group ± the standard deviation is plotted for five different serum dilutions.