![]() However, the expected disease dynamics have not been found in any rodent. In the western United States, several species of rodents are thought to maintain Y. In the steppes, the natural reservoir is believed to be principally the marmot. Several species of rodents serve as the main reservoir for Y. If the disease has progressed to the pneumonic form, humans can spread the bacterium to others by coughing, vomiting, and possibly sneezing. Transmission to humans is usually through the bite of infected fleas. pestis can spread from the urban environment and back. In the sylvatic cycle, the rodent is wild, but in the urban cycle, the rodent is primarily the brown rat ( Rattus norvegicus). pestis, most of the spreading occurs between rodents and fleas. In the urban and sylvatic (forest) cycles of Y. pestis is regurgitated into the wound, causing infection. pestis biofilm when the flea attempts to feed on an uninfected host, Y. pestis bacterium, which appears as a dark mass in the gut: The foregut ( proventriculus) of this flea is blocked by a Y. Oriental rat flea ( Xenopsylla cheopis) infected with the Y. The analysis focused on the transition to a growth condition mimicking growth in host cells. Proteome Ī comprehensive and comparative proteomics analysis of Y. pseudotuberculosis, differing only in the presence of specific virulence plasmids. pestis is thought to be descended from Y. Among other things, these virulence factors are required for bacterial adhesion and injection of proteins into the host cell, invasion of bacteria in the host cell (via a type-III secretion system), and acquisition and binding of iron harvested from red blood cells (by siderophores). Together, these plasmids, and a pathogenicity island called HPI, encode several proteins that cause the pathogenesis for which Y. pPla codes for a protease, Pla, that activates plasmin in human hosts and is a very important virulence factor for pneumonic plague. pFra codes for a phospholipase D that is important for the ability of Y. It also hosts two other plasmids, pPCP1 (also called pPla or pPst) and pMT1 (also called pFra) that are not carried by the other Yersinia species. ![]() Some strains are non-pathogenic, such as that of strain 91001, whose sequence was published in 2004. ![]() In 2006 the genome sequence of a strain of biovar Antiqua was completed. orientalis, obtained from a clinical isolate in the United States). medievalis), and strain CO92 (of biovar Y. Several complete genome sequences are available for various strains and subspecies of Y. Its closest relatives are the gastrointestinal pathogen Yersinia pseudotuberculosis, and, more distantly, Yersinia enterocolitica. Similar to other Yersinia species, it tests negative for urease, lactose fermentation, and indole. pestis is a non-motile coccobacillus, a facultative anaerobic bacterium with bipolar staining (giving it a safety pin appearance) that produces an antiphagocytic slime layer.
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