Bactericidal Antibody Responses to Meningococcal Recombinant Outer Membrane Proteins

TL;DR

This study shows that a recombinant protein called rPilQ406-770 can elicit strong antibody responses in mice, suggesting it could be a promising vaccine candidate for meningococcal serogroup B.

Contribution

The study identifies rPilQ406-770 as a novel antigen with higher immunogenicity and bactericidal activity compared to rPorA in mice.

Findings

Mice immunized with rPilQ406-770 showed significantly higher IgG antibody responses than those with rPorA.

Antisera from rPilQ406-770-immunized mice demonstrated strong bactericidal activity against serogroup B N. meningitidis.

Booster injections significantly enhanced IgG responses to both rPilQ406-770 and rPorA.

Abstract

Secretin PilQ is an antigenically conserved outer membrane protein that is present in most meningococci and PorA is a major protein that elicits bactericidal immune response in humans following natural disease and immunization. In the present study, BALB/c mice were immunized subcutaneously with rPilQ406-770 or rPorA together with Freund’s adjuvant (FA). Serum antibody responses to serogroup A and B Neisseria meningitides whole cells or purified proteins and functional activity of antibodies were determined by ELISA and serum bactericidal assay (SBA), respectively. Serum IgG responses were significantly increased in the immunized group with rPilQ406-770 or rPorA together with FA compared to control groups. IgG antibody response of mice immunized with rPilQ406-770 was significantly more than mice immunized with rPorA (OD at 450 nm was 1.6 versus 0.83). The booster injections were effective in increasing the responses of anti-rPilQ406-770 or anti-rPorA IgG significantly. Antisera produced against rPilQ406-770 or rPorA demonstrated strong surface reactivity to serogroup B N. meningitides in comparison with control groups. Antisera raised against rPorA or rPilQ406-770 and FA demonstrated SBA titers from 1/1024 to 1/2048 against serogroup B. The strongest bactericidal activity was detected in sera from mice immunized with rPilQ406-770 mixed with FA. These results suggest that rPilQ406-770 is a potential vaccine candidate for serogroup B N. meningitidis.

Figures