FIG 6.

Complement-mediated colostrum bactericidal activity of BCP. ProMilk, IMM-124E, and Travelan were tested for the ability to mediate killing of strain H10407 in the presence of complement. (A) Serially diluted ProMilk, IMM-124E, and Travelan supernatants were incubated with strain H10407 in the presence of baby rabbit complement for 1 h at 37°C, and the remaining viable organisms were quantified. Endpoint titers were determined as the dilution at which 50% of bacteria were killed using Reed-Muench regression. Data represent mean bactericidal titer plus SD from three experiments. Values that are significantly different (P < 0.001) between HBC and ProMilk by paired t test or Fisher's combined probability test are indicated by asterisks. (B) Inhibition of bactericidal activity by ETEC O78. Increasing concentrations of O78 COPS were preincubated with BCP (diluted at 1:25) to capture O78-specific antibodies, and the complement killing assay was performed as described above. Data represent the percent bacteria killed with respect to bacteria and complement-only control from three experiments. Values that are significantly different (P < 0.001) in the presence of O78 COPS by Fisher's combined probability test are indicated by asterisks.