Characterization of the rabbit antiserum raised against A. actinomycetemcomitans affinity-purified serotype d-specific antigen. (a) ELISA plates were coated with whole-cell preparations of A. actinomycetemcomitans strains representing serotypes a to e, serial dilutions of antiserum raised against affinity-purified serotype d-specific antigen were added, and the binding of the antiserum was detected with peroxidase-conjugated rabbit IgG. (b) The control fraction (lane 1), A. actinomycetemcomitans affinity-purified serotype d-specific antigen (lane 2), and LPS isolated from A. actinomycetemcomitans serotype d (IDH781) (lane 3) were subjected to SDS-12.5% PAGE, transferred to a nitrocellulose membrane, treated with rabbit antiserum raised against affinity-purified serotype d-specific antigen, and detected with peroxidase-conjugated goat anti-rabbit IgG.