title: Identification of Salmonella gallinarum virulence genes in a chicken infection model using PCR-based signature-tagged mutagenesis.
abstract: Salmonella gallinarum (SG) is a non-motile host-adapted salmonella that causes fowl typhoid, a severe systemic disease responsible for significant economic losses to the poultry industry worldwide. This study describes the application of a PCR-based signature-tagged mutagenesis system to identify in vivo-essential genes of SG. Ninety-six pools representing 1152 SG mutants were screened in a natural-host chicken infection model. Twenty presumptive attenuated mutants were identified and examined further. The identity of the disrupted gene in each mutant was determined by cloning of the DNA sequences adjacent to the transposon, followed by sequencing and comparison with the bacterial genome database. In vitro and in vivo competition indices were determined for each identified mutant and a total of 18 unique, attenuating gene disruptions were identified. These mutations represented six broad genomic classes: Salmonella pathogenicity island-1 (SPI-1), SPI-2, SPI-10, SPI-13, SPI-14 and non-SPI-encoded virulence genes. SPI-13 and SPI-14 are newly identified and designated in this study. Most of the genes identified in this study were not previously believed or known to play a role in the pathogenesis of SG infection in chickens. Each STM identified mutant showed competitiveness and/or virulence defects, confirmed by in vitro and in vivo assays, and challenge tests. This study should contribute to a better understanding of the pathogenic mechanisms involved in progression of disease caused by SG, and identification of novel live vaccine candidates and new potential antibiotic targets.
authors.affiliation: Biosafety Research Institute and College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: Devendra H
authors.initials: DH
authors.lastname: Shah
authors.affiliation: Biosafety Research Institute and College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: Mi-Jin
authors.initials: MJ
authors.lastname: Lee
authors.affiliation: Biosafety Research Institute and College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Park
authors.affiliation: Biosafety Research Institute and College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: John-Hwa
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Biosafety Research Institute and College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: Seong-Kug
authors.initials: SK
authors.lastname: Eo
authors.affiliation: Halim Inc., 13-14 Euryang-Ri, Samgi-Myeon, Iksan 570-883, Korea.
authors.forename: Jung-Thek
authors.initials: JT
authors.lastname: Kwon
authors.affiliation: Biosafety Research Institute and College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: Joon-Seok
authors.initials: JS
authors.lastname: Chae
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002645:Chickens / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis; D004195:Disease Models, Animal; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012475:Salmonella / Q000235:genetics* / Q000378:metabolism; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D014774:Virulence / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial