Bactericidal Antibody Responses to Meningococcal Recombinant Outer Membrane Proteins

Area of Science:

• Microbiology
• Immunology
• Vaccinology

Background:

• *Neisseria meningitidis* is a significant cause of bacterial meningitis.
• Outer membrane proteins like PilQ and PorA are key targets for vaccine development.
• Serogroup B *N. meningitidis* remains a challenge for prevention due to limited vaccine options.

Purpose of the Study:

• To evaluate the immunogenicity and functional activity of a recombinant PilQ protein (rPilQ406-770) as a potential vaccine candidate against serogroup B *N. meningitidis*.
• To compare the immune response elicited by rPilQ406-770 with that of a known vaccine antigen, PorA.

Main Methods:

• BALB/c mice were immunized with rPilQ406-770 or rPorA with Freund's adjuvant.
• Serum antibody responses were measured by ELISA against whole cells and purified proteins.
• Functional antibody activity was assessed using serum bactericidal assays (SBA).

Main Results:

• Immunization with both rPilQ406-770 and rPorA significantly increased serum IgG responses compared to controls.
• rPilQ406-770 induced a significantly higher IgG antibody response (OD at 450 nm = 1.6) than rPorA (OD at 450 nm = 0.83).
• Antisera against rPilQ406-770 and rPorA showed strong surface reactivity to serogroup B *N. meningitidis* and high SBA titers (1/1024 to 1/2048), with rPilQ406-770 demonstrating the strongest bactericidal activity.

Conclusions:

• Recombinant PilQ (rPilQ406-770) is immunogenic and elicits a robust bactericidal immune response against serogroup B *N. meningitidis* in a mouse model.
• rPilQ406-770 demonstrates superior immunogenicity compared to rPorA in this study.
• rPilQ406-770 represents a promising candidate for the development of a serogroup B *N. meningitidis* vaccine.