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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.

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Related in: MedlinePlus

Serum bactericidal activity of anti-Msf1–203 antibodies.A) H44/76 Msf++Δopc and its Δmsf Δopc mutant were incubated in the presence of varying concentrations of purified rabbit anti-Msf1–203 as described in methods. A dose dependent increase in killing of H44/76 Msf++Δopc (solid line) but not its Δmsf mutant (dashed line) was observed. Two independent experiments were carried out incorporating triplicate determinations. Ranges and average values of the means from these experiments are shown. B) In a control experiment the Nm derivatives were incubated with rabbit antiserum raised against bacterial cell lysates. Both strains were equally susceptible to killing in the presence of rabbit anti-Nm polyclonal antiserum. For B) Means and standard deviations are shown n = 3.
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pone.0124133.g008: Serum bactericidal activity of anti-Msf1–203 antibodies.A) H44/76 Msf++Δopc and its Δmsf Δopc mutant were incubated in the presence of varying concentrations of purified rabbit anti-Msf1–203 as described in methods. A dose dependent increase in killing of H44/76 Msf++Δopc (solid line) but not its Δmsf mutant (dashed line) was observed. Two independent experiments were carried out incorporating triplicate determinations. Ranges and average values of the means from these experiments are shown. B) In a control experiment the Nm derivatives were incubated with rabbit antiserum raised against bacterial cell lysates. Both strains were equally susceptible to killing in the presence of rabbit anti-Nm polyclonal antiserum. For B) Means and standard deviations are shown n = 3.

Mentions: In serum killing experiments using 10% human serum with increasing concentrations of purified anti-Msf1–203 antibodies, killing of Msf-expressing Nm strain H44/76 Msf++Δopc compared to the Δmsf mutant were observed at all concentrations of antibody used (Fig 8A). In control experiments, both H44/76 Msf++Δopc and H44/76 Δmsf Δopc were killed equally well by rabbit polyclonal anti-meningococcal antiserum (Fig 8B). These data support the notion that meningococcal killing in this instance is specifically mediated by anti-Msf antibodies directed against Msf on the bacterial surface and specifically the Msf regions involved in binding to aVn.


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)

Serum bactericidal activity of anti-Msf1–203 antibodies.A) H44/76 Msf++Δopc and its Δmsf Δopc mutant were incubated in the presence of varying concentrations of purified rabbit anti-Msf1–203 as described in methods. A dose dependent increase in killing of H44/76 Msf++Δopc (solid line) but not its Δmsf mutant (dashed line) was observed. Two independent experiments were carried out incorporating triplicate determinations. Ranges and average values of the means from these experiments are shown. B) In a control experiment the Nm derivatives were incubated with rabbit antiserum raised against bacterial cell lysates. Both strains were equally susceptible to killing in the presence of rabbit anti-Nm polyclonal antiserum. For B) Means and standard deviations are shown n = 3.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0124133.g008: Serum bactericidal activity of anti-Msf1–203 antibodies.A) H44/76 Msf++Δopc and its Δmsf Δopc mutant were incubated in the presence of varying concentrations of purified rabbit anti-Msf1–203 as described in methods. A dose dependent increase in killing of H44/76 Msf++Δopc (solid line) but not its Δmsf mutant (dashed line) was observed. Two independent experiments were carried out incorporating triplicate determinations. Ranges and average values of the means from these experiments are shown. B) In a control experiment the Nm derivatives were incubated with rabbit antiserum raised against bacterial cell lysates. Both strains were equally susceptible to killing in the presence of rabbit anti-Nm polyclonal antiserum. For B) Means and standard deviations are shown n = 3.
Mentions: In serum killing experiments using 10% human serum with increasing concentrations of purified anti-Msf1–203 antibodies, killing of Msf-expressing Nm strain H44/76 Msf++Δopc compared to the Δmsf mutant were observed at all concentrations of antibody used (Fig 8A). In control experiments, both H44/76 Msf++Δopc and H44/76 Δmsf Δopc were killed equally well by rabbit polyclonal anti-meningococcal antiserum (Fig 8B). These data support the notion that meningococcal killing in this instance is specifically mediated by anti-Msf antibodies directed against Msf on the bacterial surface and specifically the Msf regions involved in binding to aVn.

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