Outer membrane vesicles of Neisseria lactamica as a potential mucosal adjuvant

Area of Science:

• Immunology
• Vaccinology
• Microbiology

Background:

• Mucosal vaccine delivery offers advantages like ease of administration and induction of localized immune responses at pathogen entry sites.
• Neisseria lactamica and Neisseria meningitidis are related bacteria, with potential for cross-protective immunity.

Purpose of the Study:

• To evaluate the immunogenicity and adjuvant properties of outer membrane vesicles (OMV) from Neisseria lactamica and Neisseria meningitidis via different administration routes.
• To assess the potential for cross-reactive immune responses and protective efficacy against Neisseria meningitidis infections.

Main Methods:

• Mice were immunized with N. lactamica or N. meningitidis OMV via subcutaneous (SC) or intranasal (IN) routes, or with live N. lactamica cells.
• Immune responses, including systemic IgG and mucosal IgA, were measured.
• Adjuvant activity was assessed by co-administering OMV with hepatitis B surface antigen (HBsAg).
• Bactericidal activity and passive protection assays were performed using serum antibodies.

Main Results:

• Both N. lactamica and N. meningitidis OMV induced systemic IgG and mucosal IgA responses.
• N. lactamica OMV induced antibodies cross-reactive with N. meningitidis, particularly after three IN doses.
• OMV acted as effective intranasal adjuvants for HBsAg, inducing specific IgG and IgA.
• IN administration of N. meningitidis OMV elicited bactericidal antibodies and passive protection against meningococcal disease.

Conclusions:

• Intranasal administration of N. lactamica OMV can elicit immune responses cross-reactive with N. meningitidis.
• OMV serve as effective mucosal adjuvants, enhancing immune responses to co-administered antigens.
• These findings support the potential of OMV-based intranasal vaccines for preventing infections caused by Neisseria species.