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Updated: Apr 15, 2026
Assays for Studying the Role of Vitronectin in Bacterial Adhesion and Serum Resistance
Published on: October 16, 2018
Identification and therapeutic potential of a vitronectin binding region of meningococcal msf
Darryl J Hill1, Natalie J Griffiths1, Elena Borodina1
1School of Cellular & Molecular Medicine, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 ITD, United Kingdom.
Abstract:
The human pathogen Neisseria meningitides (Nm) attains serum resistance via a number of mechanisms, one of which involves binding to the host complement regulator protein vitronectin. We have shown previously that the Meningococcal surface fibril (Msf), a trimeric autotransporter, binds to the activated form of vitronectin (aVn) to increase Nm survival in human serum. In this study, we aimed to identify the aVn-binding region of Msf to assess its potential as an antigen which can elicit antibodies that block aVn binding and/or possess bactericidal properties. Using several recombinant Msf fragments spanning its surface-exposed region, the smallest aVn-binding recombinants were found to span residues 1-86 and 39-124. The use of further deletion constructs and overlapping recombinant Msf fragments suggested that a region of Msf comprising residues 39-82 may be primarily important for aVn binding and that other regions may also be involved but to a lesser extent. Molecular modelling implicated K66 and K68, conserved in all available Msf sequences, to be involved in the interaction. Recombinant fragments which bound to aVn were able to reduce the survival advantage conveyed by aVn-interaction in serum bactericidal assays. Antibodies raised against one such fragment inhibited aVn binding to Msf. In addition, the antibodies enhanced specific killing of Msf-expressing Nm in a dose-dependent manner. Overall, this study identifies an aVn-binding region of Msf, an adhesin known to impart serum resistance properties to the pathogen; and shows that this region of Msf can elicit antibodies with dual properties which reduce pathogen survival within the host and thus has potential as a vaccine antigen.
Insights
Researchers identified a key region on Neisseria meningitidis surface fibril (Msf) that binds to vitronectin, crucial for pathogen survival. Antibodies targeting this Msf region offer dual protection by blocking vitronectin binding and enhancing bacterial killing, showing vaccine potential.
Area of Science:
- Microbiology and Immunology
- Pathogen-Host Interactions
- Vaccine Development
Background:
- Neisseria meningitidis (Nm) evades host defenses, including complement-mediated serum killing, through mechanisms like binding to host proteins.
- The Meningococcal surface fibril (Msf) protein is known to bind activated vitronectin (aVn), conferring serum resistance to Nm.
- Understanding the specific Msf-aVn interaction is critical for developing strategies to combat Nm infections.
Purpose of the Study:
- To pinpoint the vitronectin-binding region of the Msf protein.
- To evaluate the potential of this Msf region as a vaccine antigen.
- To assess if antibodies targeting this region can block aVn binding and/or induce bactericidal activity.
Main Methods:
- Utilized recombinant Msf fragments to map the aVn-binding site.
- Employed deletion constructs and overlapping fragments to refine the binding region identification.
- Performed molecular modeling to predict key amino acid residues involved in binding.
- Conducted serum bactericidal assays with Msf fragments and generated antibodies.
Main Results:
- Identified Msf residues 39-82 as a primary aVn-binding region, with contributions from other areas.
- Molecular modeling suggested conserved residues K66 and K68 are critical for aVn interaction.
- Recombinant Msf fragments binding aVn reduced Nm's survival advantage in serum.
- Antibodies raised against a specific Msf fragment successfully inhibited aVn binding and enhanced Nm killing.
Conclusions:
- The study successfully mapped the vitronectin-binding region of the Msf adhesin.
- This Msf region elicits antibodies with dual protective functions: inhibiting pathogen adhesion and promoting bacterial clearance.
- The identified Msf region represents a promising candidate antigen for developing a novel vaccine against Neisseria meningitidis.
