title: Development of real-time PCR assays for specific detection of hmsH, hmsF, hmsR, and irp2 located within the 102-kb pgm locus of Yersinia pestis.
abstract: Virulent isolates of three pathogenic Yersinia species (Yersinia pestis, Yersinia pseudotuberculosis, and Yersinia enterocolitica) harbor a 102-kb chromosomal region which encodes elements critical for virulence. A 35-kb high pathogenicity island is contained in this region, is a known virulence determinant, contains irp1 and irp2 iron-regulating genes. An additional segment, the 68-kb high pathogenicity island, contains genetic elements responsible for conferring the Y. pestis pigmentation phenotype on Congo red agar at 28 °C. Collectively, these contiguous segments are referred to as the pigmentation (pgm) locus, the absence of which results in strain attenuation and exemption from CDC Select Agent status. In this study, we developed a set of four real-time PCR assays to detect the presence or absence of multiple virulence genes located within this region. Specifically, we designed TaqMan(®) PCR assays to individually detect three hemin storage genes (hmsH, hmsF, and hmsR) which are genetic elements that confer the pigmentation phenotype, as well as the iron-regulating status of 25 Y. pestis isolates (representing 23 different strains), thus establishing a molecular based assay capable of determining the pgm status of candidate Y. pestis isolates. Included in the validation process, was a comparison of these real-time PCR assays and newly developed conventional PCR assays targeting much larger areas of the 102-kb region (including one assay spanning hmsR and hmsF, one spanning hmsH and hsmF, one targeting hmsF, and one targeting irp2). There was high concordance between the conventional and real-time PCR assays for all Y. pestis strains tested. The results from the comparative analysis document the specificity and sensitivity of the real-time PCR assays and further solidify the ostensible benefits of real-time PCR over conventional PCR.
authors.affiliation: Diagnostic Systems Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA.
authors.forename: Charla E
authors.initials: CE
authors.lastname: Gaddy
authors.affiliation: Diagnostic Systems Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA.
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Cuevas
authors.affiliation: Diagnostic Systems Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA; ClinicalRM, Inc., Hinckley, OH, USA.
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: Hartman
authors.affiliation: Diagnostic Systems Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA.
authors.forename: Gerald B
authors.initials: GB
authors.lastname: Howe
authors.affiliation: Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA.
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Worsham
authors.affiliation: Diagnostic Systems Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA. Electronic address: timothy.d.minogue.civ@mail.mil.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Minogue
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000235:genetics; D023061:Gene Order; D035942:Iron Regulatory Protein 2 / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D014774:Virulence / Q000235:genetics; D015010:Yersinia pestis / Q000235:genetics* / Q000472:pathogenicity
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C082669:HmsF protein, Yersinia pestis; C082666:HmsH protein, Yersinia pestis; C082670:HmsR protein, Yersinia pestis; D008565:Membrane Proteins; D035942:Iron Regulatory Protein 2
keywords: CDC select agents; High pathogenicity island (HPI); Real-time PCR; Yersinia pestis; pgm locus