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Characterization of Two Metal Binding Lipoproteins as Vaccine Candidates for Enterococcal Infections.

Romero-Saavedra F, Laverde D, Budin-Verneuil A, Muller C, Bernay B, Benachour A, Hartke A, Huebner J - PLoS ONE (2015)

Bottom Line: The recombinant proteins were used to produce rabbit polyclonal antibodies that were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5.Overall, our results demonstrate that these two metal binding lipoproteins elicited specific, opsonic and protective antibodies, with an extensive cross-reactivity and serotype-independent coverage among these two important nocosomial pathogens.Pointing these two protein antigens as promising immunogens, that can be used as single components or as carrier proteins together with polysaccharide antigens in vaccine development against enterococcal infections.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine, University Medical Center Freiburg, Freiburg, Germany; EA4655 U2RM Stress/Virulence, University of Caen Lower-Normandy, Caen, France.

ABSTRACT

Background: Enterococcus faecium and faecalis are Gram-positive opportunistic pathogens that have become leading causes of nosocomial infections over the last decades. Especially multidrug resistant enterococci have become a challenging clinical problem worldwide. Therefore, new treatment options are needed and the identification of alternative targets for vaccine development has emerged as a feasible alternative to fight the infections caused by these pathogens.

Results: We extrapolate the transcriptomic data from a mice peritonitis infection model in E. faecalis to identify putative up-regulated surface proteins under infection conditions in E. faecium. After the bionformatic analyses two metal binding lipoproteins were identified to have a high homology (>72%) between the two species, the manganese ABC transporter substrate-binding lipoprotein (PsaAfm,) and the zinc ABC transporter substrate-binding lipoprotein (AdcAfm). These candidate lipoproteins were overexpressed in Escherichia coli and purified. The recombinant proteins were used to produce rabbit polyclonal antibodies that were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5. Mice were passively immunized with the antibodies raised against recombinant lipoproteins, showing significant reduction of colony counts in mice livers after the bacterial challenge and demonstrating the efficacy of these metal binding lipoproteins as promising vaccine candidates to treat infections caused by these enterococcal pathogens.

Conclusion: Overall, our results demonstrate that these two metal binding lipoproteins elicited specific, opsonic and protective antibodies, with an extensive cross-reactivity and serotype-independent coverage among these two important nocosomial pathogens. Pointing these two protein antigens as promising immunogens, that can be used as single components or as carrier proteins together with polysaccharide antigens in vaccine development against enterococcal infections.

No MeSH data available.


Related in: MedlinePlus

Opsonophagocytic assay used to test the ability to mediate opsonic killing in strains E. faecium E155, E. faecium E1162, E. faecalis 12030, E. faecalis type 2 and E. faecalis type 5 by antibodies raised against the recombinant proteins at dilutions between 1:10 and 1:100.AdcAfm (square grid) and PsaAfm (vertical stripes), compared with the activity of the preimune rabbit serum (white bar). The different sera and the corresponding dilutions used in the OPA are indicated in the abscissa and the % killing in the ordinate. Bars represent the mean of data and the error bars represent the standard error of the mean.
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pone.0136625.g004: Opsonophagocytic assay used to test the ability to mediate opsonic killing in strains E. faecium E155, E. faecium E1162, E. faecalis 12030, E. faecalis type 2 and E. faecalis type 5 by antibodies raised against the recombinant proteins at dilutions between 1:10 and 1:100.AdcAfm (square grid) and PsaAfm (vertical stripes), compared with the activity of the preimune rabbit serum (white bar). The different sera and the corresponding dilutions used in the OPA are indicated in the abscissa and the % killing in the ordinate. Bars represent the mean of data and the error bars represent the standard error of the mean.

Mentions: To determine if the antibodies directed against the recombinant proteins were able to opsonize other enterococcal strains, serum dilutions between 1:10 and 1:75 were tested in OPAs against E. faecium E1162 and E. faecalis strains 12030, type 2 and type 5 [28,29]. The two anti-protein sera were able to opsonize effectively all strains, exhibiting killing above 50% (see Fig 4). A lower opsonophagocytic killing activity was observed for the homologous strain E. faecium E155 as well as for E. faecalis strains type 2 and type 5 in comparison with strains E. faecalis 12030 and E. faecium E1162.


Characterization of Two Metal Binding Lipoproteins as Vaccine Candidates for Enterococcal Infections.

Romero-Saavedra F, Laverde D, Budin-Verneuil A, Muller C, Bernay B, Benachour A, Hartke A, Huebner J - PLoS ONE (2015)

Opsonophagocytic assay used to test the ability to mediate opsonic killing in strains E. faecium E155, E. faecium E1162, E. faecalis 12030, E. faecalis type 2 and E. faecalis type 5 by antibodies raised against the recombinant proteins at dilutions between 1:10 and 1:100.AdcAfm (square grid) and PsaAfm (vertical stripes), compared with the activity of the preimune rabbit serum (white bar). The different sera and the corresponding dilutions used in the OPA are indicated in the abscissa and the % killing in the ordinate. Bars represent the mean of data and the error bars represent the standard error of the mean.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556446&req=5

pone.0136625.g004: Opsonophagocytic assay used to test the ability to mediate opsonic killing in strains E. faecium E155, E. faecium E1162, E. faecalis 12030, E. faecalis type 2 and E. faecalis type 5 by antibodies raised against the recombinant proteins at dilutions between 1:10 and 1:100.AdcAfm (square grid) and PsaAfm (vertical stripes), compared with the activity of the preimune rabbit serum (white bar). The different sera and the corresponding dilutions used in the OPA are indicated in the abscissa and the % killing in the ordinate. Bars represent the mean of data and the error bars represent the standard error of the mean.
Mentions: To determine if the antibodies directed against the recombinant proteins were able to opsonize other enterococcal strains, serum dilutions between 1:10 and 1:75 were tested in OPAs against E. faecium E1162 and E. faecalis strains 12030, type 2 and type 5 [28,29]. The two anti-protein sera were able to opsonize effectively all strains, exhibiting killing above 50% (see Fig 4). A lower opsonophagocytic killing activity was observed for the homologous strain E. faecium E155 as well as for E. faecalis strains type 2 and type 5 in comparison with strains E. faecalis 12030 and E. faecium E1162.

Bottom Line: The recombinant proteins were used to produce rabbit polyclonal antibodies that were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5.Overall, our results demonstrate that these two metal binding lipoproteins elicited specific, opsonic and protective antibodies, with an extensive cross-reactivity and serotype-independent coverage among these two important nocosomial pathogens.Pointing these two protein antigens as promising immunogens, that can be used as single components or as carrier proteins together with polysaccharide antigens in vaccine development against enterococcal infections.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine, University Medical Center Freiburg, Freiburg, Germany; EA4655 U2RM Stress/Virulence, University of Caen Lower-Normandy, Caen, France.

ABSTRACT

Background: Enterococcus faecium and faecalis are Gram-positive opportunistic pathogens that have become leading causes of nosocomial infections over the last decades. Especially multidrug resistant enterococci have become a challenging clinical problem worldwide. Therefore, new treatment options are needed and the identification of alternative targets for vaccine development has emerged as a feasible alternative to fight the infections caused by these pathogens.

Results: We extrapolate the transcriptomic data from a mice peritonitis infection model in E. faecalis to identify putative up-regulated surface proteins under infection conditions in E. faecium. After the bionformatic analyses two metal binding lipoproteins were identified to have a high homology (>72%) between the two species, the manganese ABC transporter substrate-binding lipoprotein (PsaAfm,) and the zinc ABC transporter substrate-binding lipoprotein (AdcAfm). These candidate lipoproteins were overexpressed in Escherichia coli and purified. The recombinant proteins were used to produce rabbit polyclonal antibodies that were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5. Mice were passively immunized with the antibodies raised against recombinant lipoproteins, showing significant reduction of colony counts in mice livers after the bacterial challenge and demonstrating the efficacy of these metal binding lipoproteins as promising vaccine candidates to treat infections caused by these enterococcal pathogens.

Conclusion: Overall, our results demonstrate that these two metal binding lipoproteins elicited specific, opsonic and protective antibodies, with an extensive cross-reactivity and serotype-independent coverage among these two important nocosomial pathogens. Pointing these two protein antigens as promising immunogens, that can be used as single components or as carrier proteins together with polysaccharide antigens in vaccine development against enterococcal infections.

No MeSH data available.


Related in: MedlinePlus