title: Virulence Studies of Different Sequence Types and Geographical Origins of Streptococcus suis Serotype 2 in a Mouse Model of Infection.
abstract: Multilocus sequence typing previously identified three predominant sequence types (STs) of Streptococcus suis serotype 2: ST1 strains predominate in Eurasia while North American (NA) strains are generally ST25 and ST28. However, ST25/ST28 and ST1 strains have also been isolated in Asia and NA, respectively. Using a well-standardized mouse model of infection, the virulence of strains belonging to different STs and different geographical origins was evaluated. Results demonstrated that although a certain tendency may be observed, S. suis serotype 2 virulence is difficult to predict based on ST and geographical origin alone; strains belonging to the same ST presented important differences of virulence and did not always correlate with origin. The only exception appears to be NA ST28 strains, which were generally less virulent in both systemic and central nervous system (CNS) infection models. Persistent and high levels of bacteremia accompanied by elevated CNS inflammation are required to cause meningitis. Although widely used, in vitro tests such as phagocytosis and killing assays require further standardization in order to be used as predictive tests for evaluating virulence of strains. The use of strains other than archetypal strains has increased our knowledge and understanding of the S. suis serotype 2 population dynamics.
authors.affiliation: Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte St., Saint-Hyacinthe, QC J2S 2M2, Canada. jean-philippe.auger.1@umontreal.ca.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Auger
authors.affiliation: Public Health Ontario and Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada. nahuel.fittipaldi@oahpp.ca.
authors.forename: Nahuel
authors.initials: N
authors.lastname: Fittipaldi
authors.affiliation: Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte St., Saint-Hyacinthe, QC J2S 2M2, Canada. marie-odile.benoit-biancamano@umontreal.ca.
authors.forename: Marie-Odile
authors.initials: MO
authors.lastname: Benoit-Biancamano
authors.affiliation: Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte St., Saint-Hyacinthe, QC J2S 2M2, Canada. mariela.segura@umontreal.ca.
authors.forename: Mariela
authors.initials: M
authors.lastname: Segura
authors.affiliation: Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte St., Saint-Hyacinthe, QC J2S 2M2, Canada. marcelo.gottschalk@umontreal.ca.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
keywords: Streptococcus suis serotype 2; blood bactericidal assay; inflammation; mouse model; phagocytosis; sequence type; virulence