FIG. 2.

STa competitive ELISA to detect expression of STa proteins in the STa recombinant 8330 (STa) and mutant strains 8413 (STa₁₁), 8415 (STa₁₂), and 8417 (STa₁₃). A 1.25-ng portion of STa-ovalbumin conjugate was applied to each well; anti-STa serum (1:10,000) was used as the primary antibody and horseradish peroxidase-conjugated goat anti-rabbit immunoglobulin (IgG; 1:10,000) was used as the secondary antibody. Optical densities were measured at 405 nm. Error bars indicate standard deviations.