Protective activities of monoclonal antibodies in complement-sufficient (HsdBrlHan:WIST and PVG/c+) and C6-deficient (PVG/c−) infant rats. a) Nmb735, B-PS-specific mouse IgG2a antibody; b) MN12H2, P1.16 PorA-specific mouse IgG2a antibody; c) hIgG1, P1.16 PorA-specific human IgG1 isotype derived from MN12H2. The results are given as GM bacteremia level (CFU per milliliter of blood) in each group of five or six animals. Error bars indicate upper 95% confidence levels. *, P < 0.05 compared to control animals not given antibody, LSD. **, P value obtained with one-way ANOVA.