Project description:Yunnan Province, China is thought to be the original source of biovar Orientalis of Yersinia pestis, the causative agent of the third plague pandemic that has spread globally since the end of the 19th century. Although encompassing a large area of natural plague foci, Y. pestis strains have rarely been found in live rodents during surveillance in Yunnan, and most isolates are from rodent corpses and their fleas. In 2017, 10 Y. pestis strains were isolated from seven live rodents and three fleas in Heqing County (HQ) of Yunnan. These strains were supposed to have low virulence to local rodents Eothenomys miletus and Apodemus chevrieri because the rodents were healthy and no dead animals were found in surrounding areas, as had occurred in previous epizootic disease. We performed microscopic and biochemical examinations of the isolates,and compared their whole-genome sequences and transcriptome with those of 10 high virulence Y. pestis strains that were isolated from the adjacent city (Lijiang). We analyzed the phenotypic, genomic, and transcriptomic characteristics of live rodent isolates. The isolates formed a previously undefined monophyletic branch of Y. pestis that was named 1.IN5. Six SNPs, two indels, and one copy number variation were detected between live rodent isolates and the high virulence neighbors. No obvious functional consequence of these variations was found according to the known annotation information. Among the genes that were differentially expressed between the live rodent isolates and their high virulence neighbors, we detected five iron transfer-related genes that were significantly up-regulated in live rodent isolates compared with high virulence isolates (|log2 (FC) | >1, p.adjust <0.05), indicating these genes may be related to the low-virulence phenotype. The novel genotype of Y. pestis reported here provides further insights into the evolution and spread of plague as well as clues that may help to decipher the virulence mechanism of this notorious pathogen.

Project description:Yersinia pestis (Y. pestis) is the etiologic agent of the plague, an endemic zoonotic disease of critical clinical and historic importance. The species belongs to a genus comprising eleven members, three of which are human pathogens. Y. pestis and its closest extant relative, Yersinia pseudotuberculosis, are very similar in many respects, yet there is a distinct dichotomy between these species in terms of pathogenicity. Y. pseudotuberculosis produces a relatively benign food- or water-borne gastroenteritis with rare cases of potentially fatal bacteremia. In contrast, the characteristics of high infectivity and high mortality have made Y. pestis a pathogen of historic importance with devastating effects on the human populace over the course of three major pandemics. These qualities coupled with the emergence of multi-drug resistant variants make Y. pestis an ideal candidate for use as a bioterrorism agent. Consequentially, evolutionary biology of this organism has become a priority in the counter-terrorism research effort. The flow of genetic information within the Y. pseudotuberculosis/Y. pestis group motivated us to identify novel genes for the purpose of creating a pan-genome species DNA microarray to better understand the phylogenomic relationships among its members. Based on the sequence information be generated from the novel gene discovery project conducted at the PFGRC as well as other publicly available sources regarding Yersinia spp. genome sequences, we designed a species microarray which represents the hitherto known genetic repertoire of this taxonomic group. In order to create a species microarray that represents novel genes or genes with significant sequence variation, the ArrayOligoSelector software (http://arrayoligosel.sourceforge.net/) was used to design a 70-mer oligonucleotide for each of the annotated ORFs or partial ORFs. A detailed description of the 70-mer oligo design process and filters developed by the PFGRC can be found on the PFGRC web site at (http://pfgrc.tigr.org/presentations/seminars/oligo_design_final.pdf).

Project description:Yersinia pestis (Y. pestis) is the etiologic agent of the plague, an endemic zoonotic disease of critical clinical and historic importance. The species belongs to a genus comprising eleven members, three of which are human pathogens. Y. pestis and its closest extant relative, Yersinia pseudotuberculosis, are very similar in many respects, yet there is a distinct dichotomy between these species in terms of pathogenicity. Y. pseudotuberculosis produces a relatively benign food- or water-borne gastroenteritis with rare cases of potentially fatal bacteremia. In contrast, the characteristics of high infectivity and high mortality have made Y. pestis a pathogen of historic importance with devastating effects on the human populace over the course of three major pandemics. These qualities coupled with the emergence of multi-drug resistant variants make Y. pestis an ideal candidate for use as a bioterrorism agent. Consequentially, evolutionary biology of this organism has become a priority in the counter-terrorism research effort. The flow of genetic information within the Y. pseudotuberculosis/Y. pestis group motivated us to identify novel genes for the purpose of creating a pan-genome species DNA microarray to better understand the phylogenomic relationships among its members. Based on the sequence information be generated from the novel gene discovery project conducted at the PFGRC as well as other publicly available sources regarding Yersinia spp. genome sequences, we designed a species microarray which represents the hitherto known genetic repertoire of this taxonomic group. In order to create a species microarray that represents novel genes or genes with significant sequence variation, the ArrayOligoSelector software (http://arrayoligosel.sourceforge.net/) was used to design a 70-mer oligonucleotide for each of the annotated ORFs or partial ORFs. A detailed description of the 70-mer oligo design process and filters developed by the PFGRC can be found on the PFGRC web site at (http://pfgrc.tigr.org/presentations/seminars/oligo_design_final.pdf). One hundred fifty six query strains were investigated in this study, with each query strain hybridized against the reference strain, CO92. Each strain has a single dye experiment. Each oligo is spotted on the Y. pestis species microarray once. Positive controls on the array consist of oligos designed from the sequenced reference genome, CO92, and negative controls on the array consist of oligos designed from the thale cress plant, Arabidopsis thaliana.The microarrays also had Agilent internal controls.

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