title: Virulence Characterization of Salmonella enterica by a New Microarray: Detection and Evaluation of the Cytolethal Distending Toxin Gene Activity in the Unusual Host S. Typhimurium.
abstract: Salmonella enterica is a zoonotic foodborne pathogen that causes acute gastroenteritis in humans. We assessed the virulence potential of one-hundred and six Salmonella strains isolated from food animals and products. A high through-put virulence genes microarray demonstrated Salmonella Pathogenicity Islands (SPI) and adherence genes were highly conserved, while prophages and virulence plasmid genes were variably present. Isolates were grouped by serotype, and virulence plasmids separated S. Typhimurium in two clusters. Atypical microarray results lead to whole genome sequencing (WGS) of S. Infantis Sal147, which identified deletion of thirty-eight SPI-1 genes. Sal147 was unable to invade HeLa cells and showed reduced mortality in Galleria mellonella infection model, in comparison to a SPI-1 harbouring S. Infantis. Microarray and WGS of S. Typhimurium Sal199, established for the first time in S. Typhimurium presence of cdtB and other Typhi-related genes. Characterization of Sal199 showed cdtB genes were upstream of transposase IS911, and co-expressed with other Typhi-related genes. Cell cycle arrest, cytoplasmic distension, and nuclear enlargement were detected in HeLa cells infected by Sal199, but not with S. Typhimurium LT2. Increased mortality of Galleria was detected on infection with Sal199 compared to LT2. Thus, Salmonella isolates were rapidly characterized using a high through-put microarray; helping to identify unusual virulence features which were corroborated by further characterisation. This work demonstrates that the use of suitable screening methods for Salmonella virulence can help assess the potential risk associated with certain Salmonella to humans. Incorporation of such methodology into surveillance could help reduce the risk of emergence of epidemic Salmonella strains.
authors.affiliation: Faculty of Pharmacy and Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Department of Bacteriology, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.
authors.forename: Rui
authors.initials: R
authors.lastname: Figueiredo
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.
authors.forename: Roderick
authors.initials: R
authors.lastname: Card
authors.affiliation: Faculty of Pharmacy and Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Nunes
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.
authors.forename: Manal
authors.initials: M
authors.lastname: AbuOun
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.
authors.forename: Mary C
authors.initials: MC
authors.lastname: Bagnall
authors.affiliation: Specialist Scientific Support, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.
authors.forename: Javier
authors.initials: J
authors.lastname: Nunez
authors.affiliation: Faculty of Pharmacy and Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Mendonça
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.
authors.forename: Muna F
authors.initials: MF
authors.lastname: Anjum
authors.affiliation: Faculty of Pharmacy and Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
authors.forename: Gabriela Jorge
authors.initials: GJ
authors.lastname: da Silva
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial / Q000235:genetics; D044404:Genomic Islands / Q000235:genetics*; D019073:HT29 Cells; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D009036:Moths / Q000382:microbiology; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D010957:Plasmids / Q000235:genetics; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012481:Salmonella Infections, Animal / Q000175:diagnosis / Q000382:microbiology*; D019779:Salmonella enterica / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D012486:Salmonella typhimurium / Q000145:classification / Q000235:genetics / Q000472:pathogenicity; D012703:Serotyping / Q000379:methods; D013045:Species Specificity; D014774:Virulence / Q000235:genetics
chemical_list: D001427:Bacterial Toxins; C067044:cytolethal distending toxin