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.