FIG. 1.

Survival of N. meningitidis in pooled NHS. Bacterial strains were LNP10846 (wild type) and LNP13820 (mutant). Values represent the mean of three independent experiments ± standard deviation. The proportion of CFU surviving in sera after 30 min of exposure was significantly higher for the mutant than for the wild strain (P < 0.02, Student's t test). These findings were observed in three different settings: with sera obtained before the outbreak, with sera obtained after the outbreak from the CV inhabitants, and with sera obtained after the outbreak from Saumur inhabitants.