FIG. 3.

Relationship between antibody (Ab) avidity and dose of antibody per rat required for passive protective activity (protective activity was defined as a 2-log₁₀ decrease in the number of CFU per milliliter, compared to that of control animals pretreated with preimmunization serum or PBS). (A) Challenge by group C OAc-positive strain 4243. The point shown as an open square was considered an outlier and was excluded for purposes of the curve fit. (B) Challenge by group C OAc-negative strain 4335. The respective r² values calculated by analysis of variance nonlinear regression were 0.60 for strain 4342 (P < 0.03) and 0.69 for strain 4335 (P < 0.01). Excluding the outlier for strain 4243, the r² value was 0.92 (P < 0.001).