title: Significant contribution of the pgdA gene to the virulence of Streptococcus suis.
abstract: Streptococcus suis is a major swine pathogen and emerging zoonotic agent. In this study we have determined the muropeptide composition of S. suis peptidoglycan (PG) and found, among other modifications, N-deacetylated compounds. Comparison with an isogenic mutant showed that the product of the pgdA gene is responsible for this specific modification which occurred in very low amounts. Low level of PG N-deacetylation correlated with absence of significant lysozyme resistance when wild-type S. suis was grown in vitro. On the other hand, expression of the pgdA gene was increased upon interaction of the bacterium with neutrophils in vitro as well as in vivo in experimentally inoculated mice, suggesting that S. suis may enhance PG N-deacetylation under these conditions. Evaluation of the DeltapgdA mutant in both the CD1 murine and the porcine models of infection revealed a significant contribution of the pgdA gene to the virulence traits of S. suis. Reflecting a severe impairment in its ability to persist in blood and decreased ability to escape immune clearance mechanisms mediated by neutrophils, the DeltapgdA mutant was highly attenuated in both models. The results of this study suggest that modification of PG by N-deacetylation is an important factor in S. suis virulence.
authors.affiliation: Centre de Recherche en Infectiologie Porcine, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Canada.
authors.forename: Nahuel
authors.initials: N
authors.lastname: Fittipaldi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Sekizaki
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takamatsu
authors.forename: María
authors.initials: M
authors.lastname: de la Cruz Domínguez-Punaro
authors.forename: Josée
authors.initials: J
authors.lastname: Harel
authors.forename: Nhat Khai
authors.initials: NK
authors.lastname: Bui
authors.forename: Waldemar
authors.initials: W
authors.lastname: Vollmer
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004269:DNA, Bacterial / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009504:Neutrophils / Q000276:immunology / Q000382:microbiology; D010457:Peptidoglycan / Q000235:genetics / Q000378:metabolism*; D013290:Streptococcal Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D017011:Streptococcus suis / Q000201:enzymology / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000382:microbiology*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D010457:Peptidoglycan