MOLECULAR CHARACTERIZATION OF PATHOGENS AND THEIR RESPONSES TO ENVIRONMENTAL FACTORS
Location: Molecular Characterization of Foodborne Pathogens
Title: Virulence plasmid (pYV)-associated expression of phenotypic virulent determinants in pathogenic Yersinia species: a convenient method for monitoring the presence of pYV under culture conditions and its application for...food
Submitted to: Journal of Pathogens
Publication Type: Review Article
Publication Acceptance Date: June 27, 2011
Publication Date: September 27, 2011
Citation: Bhaduri, S., Smith, J. 2011. Virulence plasmid (pYV)-associated expression of phenotypic virulent determinants in pathogenic Yersinia species: a convenient method for monitoring the presence of pYV under culture conditions and its application for isolation/detection of Yersinia pestis in food. Journal of Pathogens. DOI: 10.4061/2011/727313.
In Yersinia pestis, Y. pseudotuberculosis, and Y, enterocolitica, phenotypic expression of virulence plasmid (pYV: 70-kb)-associated genetic determinants may include low calcium response (Lcr, pin point colony, size = 0.36 mm), colony morphology (size = 1.13 mm), crystal violet (CV) binding (dark-violet colony), Congo Red (CR) uptake (red pin point colony, size = 0.36 mm), autoagglutination (AA = cells agglutinate), and hydrophobicity (HP = clumping of cells). Y. pseudotuberculosis is chromosomally closely related to Y. pestis, whereas, Y. enterocolitica is chromosomally more distantly related to Y. pestis and Y. pseudotuberculosis. All three species demonstrate Lcr, CV binding, and CR-uptake. The colony morphology/size, AA, and HP characteristics are expressed in both Y. pseudotuberculosis and Y. enterocolitica, but not in Y. pestis. Congo red-uptake in Y. pestis was demonstrated only on calcium-deficient CR magnesium oxalate tryptic soy agar (CRMOX), whereas this phenotype was expressed on both CRMOX and low-calcium agarose media in Y. pseudotuberculosis and Y. enterocolitica. These phenotypes were detectable at 37 degrees C within 24 h in Y. enterocolitica and Y. pseudotuberculosis, but did not appear until 48 h in Y. pestis due to its slower growth rate at 37 degrees C. pYV is unstable (i.e., easily lost under a variety of culture conditions)in all three species (at less 37 degrees C)but is more unstable in Y. pestis. The specific CR-uptake by Y. pestis in CRMOX and the delayed time interval to express Lcr and CR-uptake provide a means to differentiate Y. pestis in Y. enterocolitica and Y. pseudotuberculosis. These differences in pYV expression in Y. pestis can be used for its isolation and detection from food.