FIG. 1.

ELISA inhibition with purified alpha C protein with different repeat numbers (1, 2, 9, and 16 repeats [rep]) as inhibiting antigen (Inh Ag) (left) and intact GBS with different repeat numbers (1, 2, 9, and 18 repeats) as inhibiting antigen (right). In both experiments rabbit antiserum to nine-repeat alpha C protein (final dilution, 1:8,000) was used. Microtiter plates were coated with purified nine-repeat alpha C protein at 0.125 μg/ml. Twofold dilutions were made from the inhibiting antigen (10-μg/ml starting dilution of purified alpha C protein; 10⁹-cell/ml starting dilution of intact GBS). The left panel has been modified from reference 8 and is shown here for comparison.