title: Genomic Recombination Leading to Decreased Virulence of Group B Streptococcus in a Mouse Model of Adult Invasive Disease.
abstract: Adult invasive disease caused by Group B Streptococcus (GBS) is increasing worldwide. Whole-genome sequencing (WGS) now permits rapid identification of recombination events, a phenomenon that occurs frequently in GBS. Using WGS, we described that strain NGBS375, a capsular serotype V GBS isolate of sequence type (ST)297, has an ST1 genomic background but has acquired approximately 300 kbp of genetic material likely from an ST17 strain. Here, we examined the virulence of this strain in an in vivo model of GBS adult invasive infection. The mosaic ST297 strain showed intermediate virulence, causing significantly less systemic infection and reduced mortality than a more virulent, serotype V ST1 isolate. Bacteremia induced by the ST297 strain was similar to that induced by a serotype III ST17 strain, which was the least virulent under the conditions tested. Yet, under normalized bacteremia levels, the in vivo intrinsic capacity to induce the production of pro-inflammatory cytokines was similar between the ST297 strain and the virulent ST1 strain. Thus, the diminished virulence of the mosaic strain may be due to reduced capacity to disseminate or multiply in blood during a systemic infection which could be mediated by regulatory factors contained in the recombined region.
authors.affiliation: Public Health Ontario Laboratory, 661 University Avenue, Suite 17-100, Toronto, ON M5G 1M1, Canada. sarah.teatero@oahpp.ca.
authors.forename: Sarah
authors.initials: S
authors.lastname: Teatero
authors.affiliation: Laboratory of Immunology, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC J2S 2M2, Canada. paul.lemire@umontreal.ca.
authors.forename: Paul
authors.initials: P
authors.lastname: Lemire
authors.affiliation: McGill University and Genome Quebec Innovation Centre, 740 Dr. Penfield Avenue Rm 7104, Montreal, QC H3A 0G1, Canada. ken.dewar@mcgill.ca.
authors.forename: Ken
authors.initials: K
authors.lastname: Dewar
authors.affiliation: McGill University and Genome Quebec Innovation Centre, 740 Dr. Penfield Avenue Rm 7104, Montreal, QC H3A 0G1, Canada. jessica.wasserscheid@mail.mcgill.ca.
authors.forename: Jessica
authors.initials: J
authors.lastname: Wasserscheid
authors.affiliation: Laboratory of Immunology, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC J2S 2M2, Canada. cynthia.calzas@umontreal.ca.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Calzas
authors.affiliation: Public Health Ontario Laboratory, 661 University Avenue, Suite 17-100, Toronto, ON M5G 1M1, Canada. gustavo.mallo@oahpp.ca.|Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 27 King's College Circle, Toronto, ON M5S 1A1, Canada. gustavo.mallo@oahpp.ca.
authors.forename: Gustavo V
authors.initials: GV
authors.lastname: Mallo
authors.affiliation: Public Health Ontario Laboratory, 661 University Avenue, Suite 17-100, Toronto, ON M5G 1M1, Canada. aimin.li@oahpp.ca.
authors.forename: Aimin
authors.initials: A
authors.lastname: Li
authors.affiliation: Public Health Ontario Laboratory, 661 University Avenue, Suite 17-100, Toronto, ON M5G 1M1, Canada. taryn.athey@oahpp.ca.
authors.forename: Taryn B T
authors.initials: TB
authors.lastname: Athey
authors.affiliation: Laboratory of Immunology, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC J2S 2M2, Canada. mariela.segura@umontreal.ca.
authors.forename: Mariela
authors.initials: M
authors.lastname: Segura
authors.affiliation: Public Health Ontario Laboratory, 661 University Avenue, Suite 17-100, Toronto, ON M5G 1M1, Canada. nahuel.fittipaldi@oahpp.ca.|Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 27 King's College Circle, Toronto, ON M5S 1A1, Canada. nahuel.fittipaldi@oahpp.ca.
authors.forename: Nahuel
authors.initials: N
authors.lastname: Fittipaldi
keywords: Streptococcus agalactiae; adult infection; cytokines; group B Streptococcus; invasive bacterial infection; recombination