title: Simultaneous lack of catalase and beta-toxin in Staphylococcus aureus leads to increased intracellular survival in macrophages and epithelial cells and to attenuated virulence in murine and ovine models.
abstract: Staphylococcus aureus produces a variety of virulence factors that allow it to cause a wide range of infections in humans and animals. In the latter, S. aureus is a leading cause of intramammary infections. The contribution of catalase (KatA), an enzyme implicated in oxidative stress resistance, and beta-toxin (Hlb), a haemolysin, to the pathogenesis of S. aureus is poorly characterized. To investigate the role of these enzymes as potential virulence factors in S. aureus, we examined the intracellular survival of DeltakatA, Deltahlb and DeltakatA Deltahlb mutants in murine macrophages (J774A.1) and bovine mammary epithelial cells (MAC-T), and their virulence in different murine and ovine models. Catalase was not required for the survival of S. aureus within either J774A.1 or MAC-T cells. However, it was necessary for the intracellular proliferation of the bacterium after invasion of MAC-T cells. In addition, catalase was not needed for the full virulence of S. aureus in mice. Deletion of the hlb gene had no effect on the intracellular survival of S. aureus in J774A.1 cells but did cause a slight increase in survival in MAC-T cells. Furthermore, like catalase, beta-toxin was not required for complete virulence of S. aureus in murine models. Unexpectedly, the DeltakatA Deltahlb mutant showed a notably increased persistence in both cell lines, and was significantly less virulent for mice than were the wild-type strain and single mutants. Most interestingly, it was also markedly attenuated in intramammary and subcutaneous infections in ewes and lambs.
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid‡, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Martínez-Pulgarín
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid‡, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Domínguez-Bernal
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid‡, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Orden
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid‡, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: de la Fuente
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000382:microbiology*; D005260:Female; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D012756:Sheep; D013108:Sphingomyelin Phosphodiesterase / Q000235:genetics / Q000378:metabolism*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D002374:Catalase; D013108:Sphingomyelin Phosphodiesterase; C029878:hlb protein, Staphylococcus aureus