Project description:Multidrug-resistant (MDR; resistance to >3 antimicrobial classes) Salmonella enterica serovar I 4,[5],12:i:- strains were linked to a 2015 foodborne outbreak from pork. Strain USDA15WA-1, associated with the outbreak, harbors an MDR module and the metal tolerance element Salmonella Genomic Island 4 (SGI-4). Characterization of SGI-4 revealed that conjugational transfer of SGI-4 resulted in the mobile genetic element (MGE) replicating as a plasmid or integrating into the chromosome. Tolerance to copper, arsenic, and antimony compounds was increased in Salmonella strains containing SGI-4 compared to strains lacking the MGE. Following Salmonella exposure to copper, RNA-seq transcriptional analysis demonstrated significant differential expression of diverse genes and pathways, including induction of numerous metal tolerance genes (copper, arsenic, silver, and mercury). Evaluation of swine administered elevated concentrations of zinc oxide (2,000 mg/kg) and copper sulfate (200 mg/kg) as an antimicrobial feed additive (Zn+Cu) in their diet for 4 weeks prior to and 3 weeks post-inoculation with serovar I 4,[5],12:i:- indicated that Salmonella shedding levels declined at a slower rate in pigs receiving in-feed Zn+Cu compared to control pigs (no Zn+Cu). The presence of metal tolerance genes in MDR Salmonella serovar I 4,[5],12:i:- may provide benefits for environmental survival or swine colonization in metal-containing settings.
Project description:FabR ChIP-chip on Salmonella enterica subsp. enterica serovar Typhimurium SL1344 using anti-Myc antibody against strain with chromosomally 9Myc-tagged FabR (IP samples) and wildtype strain (mock IP samples)
Project description:Salmonella enterica causes serious global burden of morbidity and mortality and is a major cause of infant bacteremia in sub Saharan Africa. Diseases caused by Salmonella are treatable with antibiotics but successful antibiotic treatment has become difficult due to antimicrobial resistance. An effective vaccine together with public health effort may therefore be a better strategy to control these infections. Protective immunity against Salmonella depends primarily on T cell-mediated immune responses and therefore identifying relevant T cell antigens is necessary for Salmonella vaccine development. Our laboratory has used an immunoproteomics approach to identify Chlamydia T cell antigens that exhibited significant protection against Chlamydia infection in mice. In this study, we infected murine bone marrow derived dendritic cells from C57BL/6 mice with Salmonella enterica strain SL1344 followed by isolation of MHC class I and II- molecules and elution of bound peptides. The sequences of the peptides were then identified using tandem mass spectrometry. We identified 87 MHC class II and 23 MHC class I Salmonella derived peptides. Four of 12 peptides stimulated IFN-? production by CD4 T cells from the spleens of mice with persistent Salmonella infection. These antigens will be useful for Salmonella immunobiology research and are potential Salmonella vaccine candidates.
Project description:Increasing evidence indicates that despite exposure to harsh environmental stresses, Salmonella enterica successfully persists on plants, utilizing fresh produce as a vector to animal hosts. This study examined the mechanisms of S. enterica plant colonization, including the role of the diguanylate cyclase AdrA. Utilizing microarray analysis, we identified a new function for AdrA in the transcriptional regulation of colanic acid biosynthesis genes.