Limits...
Identification and therapeutic potential of a vitronectin binding region of meningococcal msf.

Hill DJ, Griffiths NJ, Borodina E, Andreae CA, Sessions RB, Virji M - PLoS ONE (2015)

Bottom Line: 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.Recombinant fragments which bound to aVn were able to reduce the survival advantage conveyed by aVn-interaction in serum bactericidal assays.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.

View Article: PubMed Central - PubMed

Affiliation: School 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.

No MeSH data available.


Related in: MedlinePlus

Inhibition of aVn-mediated increased serum resistance by vitronectin-binding Msf constructs.Serum bactericidal assay using MC58 Msf+ Δopc (grey bars) MC58 Δmsf Δopc (white bars). Bacteria were incubated in normal human serum (10%) with aVn (10 μg/ml) or without aVn as indicated. Where included, Msf fragments were added at either equimolar or 10x excess molar amounts relative to aVn as indicated. In the presence of Msf1–86 but not Msf197–422 the protective effect of aVn was diminished. Data shown are average values and ranges from two independent experiments each comprising triplicate determinations.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4380367&req=5

pone.0124133.g006: Inhibition of aVn-mediated increased serum resistance by vitronectin-binding Msf constructs.Serum bactericidal assay using MC58 Msf+ Δopc (grey bars) MC58 Δmsf Δopc (white bars). Bacteria were incubated in normal human serum (10%) with aVn (10 μg/ml) or without aVn as indicated. Where included, Msf fragments were added at either equimolar or 10x excess molar amounts relative to aVn as indicated. In the presence of Msf1–86 but not Msf197–422 the protective effect of aVn was diminished. Data shown are average values and ranges from two independent experiments each comprising triplicate determinations.

Mentions: We have shown previously that the binding of Vn by Msf conveys a survival advantage to meningococci through increased resistance to serum killing [30]. Thus introduction of aVn-binding Msf fragments into serum bactericidal assays should reduce the survival advantage of Msf-expressing meningococci. Indeed Msf1–86 but not Msf197–422 reduced aVn-mediated increased serum resistance of Nm (Fig 6). This observation also suggested that such peptides may generate antibodies capable of blocking Vn interactions though binding to Msf on the surface of meningococci. Further, as anti-Msf antibodies have been reported to be bactericidal [32], antibodies directed against the Vn-binding domain of Msf may be bactericidal in addition to blocking Vn binding.


Identification and therapeutic potential of a vitronectin binding region of meningococcal msf.

Hill DJ, Griffiths NJ, Borodina E, Andreae CA, Sessions RB, Virji M - PLoS ONE (2015)

Inhibition of aVn-mediated increased serum resistance by vitronectin-binding Msf constructs.Serum bactericidal assay using MC58 Msf+ Δopc (grey bars) MC58 Δmsf Δopc (white bars). Bacteria were incubated in normal human serum (10%) with aVn (10 μg/ml) or without aVn as indicated. Where included, Msf fragments were added at either equimolar or 10x excess molar amounts relative to aVn as indicated. In the presence of Msf1–86 but not Msf197–422 the protective effect of aVn was diminished. Data shown are average values and ranges from two independent experiments each comprising triplicate determinations.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380367&req=5

pone.0124133.g006: Inhibition of aVn-mediated increased serum resistance by vitronectin-binding Msf constructs.Serum bactericidal assay using MC58 Msf+ Δopc (grey bars) MC58 Δmsf Δopc (white bars). Bacteria were incubated in normal human serum (10%) with aVn (10 μg/ml) or without aVn as indicated. Where included, Msf fragments were added at either equimolar or 10x excess molar amounts relative to aVn as indicated. In the presence of Msf1–86 but not Msf197–422 the protective effect of aVn was diminished. Data shown are average values and ranges from two independent experiments each comprising triplicate determinations.
Mentions: We have shown previously that the binding of Vn by Msf conveys a survival advantage to meningococci through increased resistance to serum killing [30]. Thus introduction of aVn-binding Msf fragments into serum bactericidal assays should reduce the survival advantage of Msf-expressing meningococci. Indeed Msf1–86 but not Msf197–422 reduced aVn-mediated increased serum resistance of Nm (Fig 6). This observation also suggested that such peptides may generate antibodies capable of blocking Vn interactions though binding to Msf on the surface of meningococci. Further, as anti-Msf antibodies have been reported to be bactericidal [32], antibodies directed against the Vn-binding domain of Msf may be bactericidal in addition to blocking Vn binding.

Bottom Line: 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.Recombinant fragments which bound to aVn were able to reduce the survival advantage conveyed by aVn-interaction in serum bactericidal assays.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.

View Article: PubMed Central - PubMed

Affiliation: School 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.

No MeSH data available.


Related in: MedlinePlus