title: Immunization with SsEno fails to protect mice against challenge with Streptococcus suis serotype 2.
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.
authors.affiliation: Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, QC, Canada.
authors.forename: Miriam
authors.initials: M
authors.lastname: Esgleas
authors.forename: Maria de la Cruz
authors.initials: Mde L
authors.lastname: Dominguez-Punaro
authors.forename: Yuanyi
authors.initials: Y
authors.lastname: Li
authors.forename: Josée
authors.initials: J
authors.lastname: Harel
authors.forename: J Daniel
authors.initials: JD
authors.lastname: Dubreuil
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001426:Bacterial Proteins / Q000276:immunology*; D005260:Female; D007116:Immunization, Passive; D007074:Immunoglobulin G / Q000097:blood; D008264:Macrophages / Q000276:immunology; D016920:Meningitis, Bacterial / Q000401:mortality / Q000517:prevention & control; D051379:Mice; D010751:Phosphopyruvate Hydratase / Q000276:immunology*; D011817:Rabbits; D018805:Sepsis / Q000401:mortality / Q000517:prevention & control; D013290:Streptococcal Infections / Q000401:mortality / Q000517:prevention & control*; D022541:Streptococcal Vaccines / Q000276:immunology*; D017011:Streptococcus suis / Q000276:immunology*; D016019:Survival Analysis; D013552:Swine / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D007074:Immunoglobulin G; D022541:Streptococcal Vaccines; C112984:streptococcal surface enolase; D010751:Phosphopyruvate Hydratase