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Sialylation and human neutrophil killing of group C Neisseria meningitidis
M M Estabrook1, N C Christopher, J M Griffiss
1Center for Immunochemistry, VA Medical Center, San Francisco, CA.
Abstract:
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.
Insights
Certain meningococcal strains evade immune defenses. Sialylation and capsule presence impact survival against neutrophil killing, potentially increasing epidemic spread.
Area of Science:
- Microbiology
- Immunology
- Bacteriology
Background:
- Neisseria meningitidis serogroup C causes invasive disease.
- Lipooligosaccharide (LOS) and capsule sialylation are key bacterial surface components.
- Understanding immune evasion mechanisms is crucial for controlling meningococcal infections.
Observation:
- The study analyzed 25 serogroup C meningococcal strains, including epidemic-associated isolates.
- Strain survival was assessed in phagocytosis assays against human neutrophils.
- The association between LOS sialylation, capsule amount, and neutrophil resistance was investigated.
Findings:
- For non-2b:P1.2 strains, LOS sialylation and capsule amount correlated with neutrophil susceptibility.
- Serotype 2b:P1.2 strains exhibited significantly higher survival against neutrophils.
- Neutrophil resistance in 2b:P1.2 strains was independent of LOS sialylation or capsule amount.
Implications:
- Virulent meningococcal strains may possess alternative mechanisms for evading neutrophil clearance.
- Evasion of neutrophil killing could be a critical factor in the epidemic potential of meningococcal bacteria.
- Further research into these evasion strategies may inform vaccine development and public health interventions.