Fig 4.

Effect of LPS on serum bactericidal activity. (A) Adult and child serum samples were analyzed by ELISA to determine levels of IgM and IgG antibodies reactive with S. Typhimurium LPS. *, P = 0.011. (B) S. Typhimurium strain SL1344 was incubated with PBS or adult serum that had been preincubated or not preincubated with 100 μg/ml of S. Typhimurium (St) or E. coli (Ec) LPS. After 60 min at 37°C, the numbers of surviving bacteria were determined by plating serial dilutions of the reaction mixtures. *, P < 0.0001; **, P < 0.0001. The dashed line indicates the starting inoculum.