Humoral Immune Response
As mentioned not much research has currently been performed, regarding the immune respsonses. What information that is available has shown that the humoral immunity does indeed play a key role in protection against N. meningitidis infection and that carriage of the bacterium results in an increased bactericidal antibody response (Yazdankhak et al., 2004). One study noted that carrying certain various strains of N. meningitidis resulted in a response against the outer-membrane proteins (PorA, PorB and Opa in particular) and the lipopolysaccharides (Jones et al., 1998); the response was found to be strain-specific with a small observed percentage of cross-reactivity between heterologous strains. Research has shown that the anti-meningococcal antibodies produced by the humoral response exhibit defensive properties via the binding of N. meningitidis surface antigens, "activation of the complement system that causes phagocytosis" (Yazdankhak et al., 2004).
Interestingly, it is not certain whether or not natural immunization against the bacterium results in long-term immunological memory (Yazdankhak et al., 2004).
More research is drastically needed to better understand the role of the humoral immune response to N. meningitidis infection.
References:
Jones, G.R., et al. "Dynamics of carriage of Neisseria meningitidis in a group of military recruits: subtype stability and specificity of the immune response following colonization." Journal of Infectious Diseases 178 (1998): 451–59.
Robinson, K., et al. "Characterization of humoral and cellular immune responses elicited by meningococcal carriage." Infection & Immunity 70.3 (2002): 1301–09.
Yazdankhak, Siamak P., and Dominique A. Caugant. "Neisseria meningitidis: an overview of the carrier stage." Journal of Medical Microbiology 53 (2004): 821-32.
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Email questions or comments to Jordan Sullivan.