Numerous studies have described

many virulence factors that are essential to suppress host immune responses [2, 31]. The direct contributions of these BI 2536 chemical structure virulence factors to bacterial dissemination, however, are still unclear. The study of dissemination per se is a field that is lagging behind in plague research. BLI is a tool that allows for the visualization of a pathogen in a host during infection and a very promising alternative to better understand Y. pestis dissemination. A recent report described the use of BLI in a subcutaneous (SC) model of bubonic plague [25]. In this report, the pGEN-luxCDABE plasmid was described to have no effect on the virulence of Y. pestis and to be suitable for BLI as luminosity correlated with bacterial counts in vivo; our results confirmed and expanded upon these findings. Our goal was to determine whether CB-839 mw BLI could be used to follow dissemination and colonization of Y. pestis

in mice after using different routes of GDC 973 inoculation that closely mimic bubonic and pneumonic plague. Moreover, we tested whether BLI could be used to detect mutants with defects in colonization or dissemination. After inoculation with a strain of Y. pestis that contains pGEN-luxCDABE, we showed that animals can be imaged through the course of infection in such a way that bacterial spread could be followed over time for three different models of infection. Our results

from the SC inoculation model support the previous notion that, during bubonic plague, Y. pestis travels from the site of inoculation to the proximal lymph node prior to dissemination to deeper tissues very [16]. We observed that bacteria were maintained at the site of inoculation during the course of infection, as previously reported for ear intradermal (ID) infections [15]. For both, the SC and ID models, the bacterial population at the site of inoculation appeared not only to be maintained, but also to expand. However, while we quantified signal from the site of infection in the SC-inoculated animals, we cannot conclude such signal comes from the skin alone. In our SC model, the patch of inoculated skin is located in an anatomical position on top of the superficial cervical LNs and thus, both, skin and LNs, are imaged as a single source of radiance. We could determine that signal was coming partly from the site of inoculation after removing the patch of skin and imaging it individually. This complication is minimized in the ID model, where the site of inoculation (ear pinna) is distant from the draining LN (superficial parotid LN). While an increase overtime in signal intensity from the ear was observed, we were not able to quantify the signal, as it was difficult to place the ears of all mice at the same position inside of the animal isolation chamber.