Fig. 3

Determination of concentrations of capture antigen & competitive antibody, and dilution of serum. a Determination of optimal concentrations of capture protein (C-strain E2) and competitive antibody (HRP-6B211); the optimal concentration of capture protein (0.625 μg/ml) and HRP-6B211 (1.25 μg/ml) was chosen as it consistently produced an OD₄₅₀ around 1.7 and at a point in the linear range that allowed optimal inhibition; b Determination of an optimal dilution of serum; To minimize the volume of serum required and background noise, serum dilution of 1:5 was chosen as the preferred dilution over lower dilutions that performed only slightly better. Data are expressed as the mean ± standard deviation from independently repeated experiments