title: Differential roles for pathogenicity islands SPI-13 and SPI-8 in the interaction of Salmonella Enteritidis and Salmonella Typhi with murine and human macrophages.
abstract: BACKGROUND
  Salmonella pathogenicity island (SPI)-13 is conserved in many serovars of S. enterica, including S. Enteritidis, S. Typhimurium and S. Gallinarum. However, it is absent in typhoid serovars such as S. Typhi and Paratyphi A, which carry SPI-8 at the same genomic location. Because the interaction with macrophages is a critical step in Salmonella pathogenicity, in this study we investigated the role played by SPI-13 and SPI-8 in the interaction of S. Enteritidis and S. Typhi with cultured murine (RAW264.7) and human (THP-1) macrophages.
  
  
  RESULTS
  Our results showed that SPI-13 was required for internalization of S. Enteritidis in murine but not human macrophages. On the other hand, SPI-8 was not required for the interaction of S. Typhi with human or murine macrophages. Of note, the presence of an intact copy of SPI-13 in a S. Typhi mutant carrying a deletion of SPI-8 did not improve its ability to be internalized by, or survive in human or murine macrophages.
  
  
  CONCLUSIONS
  Altogether, our results point out to different roles for SPI-13 and SPI-8 during Salmonella infection. While SPI-13 contributes to the interaction of S. Enteritidis with murine macrophages, SPI-8 is not required in the interaction of S. Typhi with murine or human macrophages. We hypothesized that typhoid serovars have lost SPI-13 and maintained SPI-8 to improve their fitness during another phase of human infection.
authors.affiliation: Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santos Dumont 964, Independencia, Santiago, Chile.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Espinoza
authors.affiliation: Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santos Dumont 964, Independencia, Santiago, Chile.|Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
authors.forename: Cecilia A
authors.initials: CA
authors.lastname: Silva-Valenzuela
authors.affiliation: Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santos Dumont 964, Independencia, Santiago, Chile.
authors.forename: Fernando A
authors.initials: FA
authors.lastname: Amaya
authors.affiliation: Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santos Dumont 964, Independencia, Santiago, Chile.
authors.forename: Ítalo M
authors.initials: ÍM
authors.lastname: Urrutia
authors.affiliation: Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santos Dumont 964, Independencia, Santiago, Chile. inescontreraso@gmail.com.
authors.forename: Inés
authors.initials: I
authors.lastname: Contreras
authors.affiliation: Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santos Dumont 964, Independencia, Santiago, Chile. csantiviago@ciq.uchile.cl.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Santiviago
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D018407:Bacterial Physiological Phenomena; D002470:Cell Survival; D002478:Cells, Cultured; D016680:Genome, Bacterial; D044404:Genomic Islands / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D056265:Microbial Interactions / Q000235:genetics; D009115:Muridae; D016133:Polymerase Chain Reaction; D000067996:RAW 264.7 Cells; D012480:Salmonella Infections / Q000382:microbiology*; D012477:Salmonella enteritidis / Q000235:genetics*; D012485:Salmonella typhi / Q000235:genetics*; D065288:Serogroup; D013045:Species Specificity
keywords: Enteritidis; Macrophages; RAW264.7; SPI-13; SPI-8; Salmonella; THP-1; Typhi