title: Involvement of a Salmonella genomic island 1 gene in the rumen protozoan-mediated enhancement of invasion for multiple-antibiotic-resistant Salmonella enterica serovar Typhimurium.
abstract: Multiple-antibiotic-resistant Salmonella enterica serotype Typhimurium is a food-borne pathogen that may be more virulent than related strains lacking the multiresistance phenotype. Salmonella enterica serotype Typhimurium phage type DT104 is the most prevalent of these multiresistant/hypervirulent strains. Multiresistance in DT104 is conferred by an integron structure, designated Salmonella genomic island 1 (SGI1), while we recently demonstrated DT104 hyperinvasion mediated by rumen protozoa (RPz) that are normal flora of cattle. Hyperinvasion was also observed in other Salmonella strains, i.e., other S. enterica serovar Typhimurium phage types and other S. enterica serovars, like S. enterica serovar Infantis, possessing SGI1, while DT104 strains lacking SGI1 were not hyperinvasive. Herein we attempted to identify SGI1 genes involved in the RPz-mediated hyperinvasion of Salmonella strains bearing SGI1. Transposon mutagenesis, coupled with a novel reporter system, revealed the involvement of an SGI1 gene previously designated SO13. Disruption of SO13 expression led to an abrogation of hyperinvasion as assessed by tissue culture invasion assays and by bovine challenge experiments. However, hyperinvasion was not observed in non-SGI1-bearing strains of Salmonella engineered to express SO13. That is, SO13 and another SGI1 gene(s) may coordinately upregulate invasion in DT104 exposed to RPz.
authors.affiliation: Pre-harvest Food Safety and Enteric Disease Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa 50010, USA. scarlson@nadc.ars.usda.gov
authors.forename: Steve A
authors.initials: SA
authors.lastname: Carlson
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Sharma
authors.forename: Zoe P
authors.initials: ZP
authors.lastname: McCuddin
authors.forename: Mark A
authors.initials: MA
authors.lastname: Rasmussen
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Franklin
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D004251:DNA Transposable Elements / Q000235:genetics; D004195:Disease Models, Animal; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D056890:Eukaryota / Q000502:physiology*; D017353:Gene Deletion; D005798:Genes, Bacterial; D044404:Genomic Islands; D006801:Humans; D016254:Mutagenesis, Insertional; D012417:Rumen / Q000469:parasitology; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements