2.4 Antibody titer detection
M2e- and PCV2-specific antibodies in sera were determined by indirect
ELISA using 1 μg/mL of synthesized M2e peptides as coating antigens.
Twofold serially diluted immune serum samples were added into the ELISA
plates, followed by HRP-conjugated goat anti-mouse IgG. The highest
dilution which showing over twofold OD450 readout than that of the
control sample as the antibody endpoint titer. For the detection of
PCV2-specific antibodies, commercial PCV2 antibody test kit (BioChek,
Reeuwijk, Holland) was utilized.