Human opsonins induced during meningococcal disease recognize transferrin binding protein complexes

Area of Science:

• Immunology
• Microbiology
• Vaccine Development

Background:

• Neisseria meningitidis utilizes transferrin binding protein A+B (TbpA+B) complexes for iron acquisition.
• Understanding the host immune response to TbpA+B is crucial for developing effective meningococcal vaccines.

Purpose of the Study:

• To quantify patient serum opsonins against TbpA+B complexes from different Neisseria meningitidis strains.
• To assess the functional activity of these opsonins via phagocytosis and oxidative burst assays.
• To evaluate the cross-reactivity and vaccine potential of anti-TbpA+B antibodies.

Main Methods:

• Functional phagocytosis and oxidative burst assay using fluorescently-adsorbed TbpA+B complexes.
• Opsonization with acute and convalescent sera from 40 meningococcal disease patients.
• Flow cytometric quantitation of leukocyte phagocytosis products (PP).
• Correlation analysis with immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) titers.

Main Results:

• Disease-induced serum opsonins recognized TbpA+B complexes, with peak activity observed 6 weeks post-hospital admission.
• Opsonic activity against TbpA+B from strain B16B6 was significantly higher than against strain K454 (P < 0.0001).
• Results correlated positively with higher IgG titers against TbpA+B from strain B16B6 (P < 0.001).
• Phagocytosis and oxidative burst activities were closely correlated.
• Opsonic activity was independent of TbpB protein variability between strains.

Conclusions:

• Highly cross-reactive anti-TbpA+B serum opsonins are produced during meningococcal disease.
• The observed cross-reactivity and independence from TbpB variability support the vaccine potential of TbpA+B complexes.
• TbpA+B represents a promising target for future meningococcal vaccines.