Sialylation and human neutrophil killing of group C Neisseria meningitidis.

This study describes the association of lipooligosaccharide (LOS) and capsule sialylation with the survival of 25 serogroup C meningococcal strains in phagocytosis assays. Eleven strains isolated from children were of diverse protein serotypes or were nontypeable; 14 were serotype 2b:P1.2 and were isolated from children during or immediately after a focal epidemic in Texas. Degree of endogenous LOS sialylation and amount of sialic acid capsule were associated with each other and with susceptibility to killing by neutrophils for the non-2b:P1.2 strains. The 2b:P1.2 strains as a group had significantly greater survival in the presence of neutrophils than did the non-2b:P1.2 strains. The susceptibility of these strains to killing by neutrophils was not associated with endogenous LOS sialylation or amount of capsule. These data suggest that many virulent strains evade neutrophil killing, either by sialylation or another mechanism. Evasion of neutrophil killing might enhance a strain's epidemic potential.