Immunization with SsEno fails to protect mice against challenge with Streptococcus suis serotype 2

Authors

  • Miriam Esgleas,

    1. Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, QC, Canada
    2. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, QC, Canada
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  • Maria de la Cruz Dominguez-Punaro,

    1. Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, QC, Canada
    2. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, QC, Canada
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  • Yuanyi Li,

    1. Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, QC, Canada
    2. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, QC, Canada
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  • Josée Harel,

    1. Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, QC, Canada
    2. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, QC, Canada
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  • J. Daniel Dubreuil,

    1. Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, QC, Canada
    2. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, QC, Canada
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  • Marcelo Gottschalk

    1. Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, QC, Canada
    2. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, QC, Canada
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  • Editor: Mark Schembri

Correspondence: Marcelo Gottschalk, Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, 3200 rue Sicotte, Saint-Hyacinthe, QC, Canada J2S 2M2. Tel.: +450 773 8521, ext. 1 8374; fax: +450 778 8108; e-mail: marcelo.gottschalk@umontreal.ca

Abstract

In our ongoing efforts to develop a vaccine against Streptococcus suis infection, we tested the potential of S. suis enolase (SsEno), a recently described S. suis adhesin with fibronectin-binding activity, as a vaccine candidate in a mouse model of S. suis-induced septicemia and meningitis. Here, we show that SsEno is highly recognized by sera from convalescent pigs and is highly immunogenic in mice. Subcutaneous immunization of mice with SsEno elicited strong immunoglobulin G (IgG) antibody responses. All four IgG subclasses were induced, with IgG1, IgG2a and IgG2b representing the highest titers followed by IgG3. However, SsEno-vaccinated and nonvaccinated control groups showed similar mortality rates after challenge infection with the highly virulent S. suis strain 166′. Similar results were obtained upon passive immunization of mice with hyperimmunized rabbit IgG anti-SsEno. We also showed that anti-SsEno antibodies did not increase the ability of mouse phagocytes to kill S. suis in vitro. In conclusion, these data demonstrate that although recombinant SsEno formulated with Quil A triggers a strong antibody response, it does not confer effective protection against infection with S. suis serotype 2 in mice.

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