FIG. 3.
Naïve serum resistance of wild-type and ΔbrkA mutant strains of B. pertussis at various concentrations of serum. In vitro grown bacteria were diluted to a concentration of 500 CFU/50 μl and treated with various concentrations of naïve rabbit serum for 1 h at 37°C. Serum resistance is expressed as the percentage of bacteria that survived ± the standard error. All samples were run in triplicate, and each strain was tested at least twice.