pestis travels from the site of infection to draining lymph nodes (LN) prior to disseminating throughout the rest of the body [15, 16]. Bacterial burden data from these experiments give a snapshot of a very narrow window (a specific organ at a specific time) through the course of infection. Furthermore, the approach is invasive, requires a large number of animals, and animals must be sacrificed at each

time point making it impossible to keep track of the progression of infection selleck chemicals llc on the same group of individuals. In vivo bioluminescence imaging (BLI) is an approach that has been used to detect light-emitting cells inside of small mammals [17]. Using BLI, researchers have described and studied dissemination of viral, parasitic and bacterial pathogens within a host in a non-invasive manner [18–21]. Thus, the same group of animals can be imaged for as long as desired over the course of infection. The system requires that the pathogen produce luminescence, and infected animals are then imaged with a high-sensitivity camera that detects very small amounts of light. Non-luminescent bacteria can be genetically modified to express

the lux genes (luxCDABE), which encode a bacterial luciferase and other enzymes that are necessary to generate substrate for luciferase [22]. In the presence of oxygen, luciferase catalyzes a reaction that produces light as a byproduct [23]. We transformed Y. pestis CO92 with plasmid pGEN-luxCDABE that Savolitinib chemical structure contains the luxCDABE genes [24]. Using this strain of Y. pestis expressing the lux genes we determined that it is suitable for in vivo BLI after subcutaneous, intradermal and intranasal inoculation. find more In addition, we determined that BLI is suitable for the study of mutant strains that are attenuated or defective in dissemination or colonization during infection. This extends the findings of a recent report demonstrating

the suitability of BLI to study Y. pestis infections by the subcutaneous route of inoculation [25]. BLI technology offers a new perspective to study the spread of Y. pestis in the host. This technology could be adopted in the future as an alternative to experiments that measured bacterial burdens in specific organs, facilitating the discovery Niclosamide and study of genes that are important in pathogenesis. Results The pGEN-luxCDABE vector is stable in Y. pestis during infection Bacteria carrying a reporter plasmid could potentially lose it at a specific site or time point during infection. A subpopulation lacking the plasmid could result in false negatives or decreases in signal detection that are not necessarily related to lower numbers of bacteria. To determine if pGEN-luxCDABE (pGEN-lux) was maintained during Y. pestis infections, we performed a kinetic study with mice infected with CO92 carrying pGEN-lux. Mice were inoculated subcutaneously (SC) and LN harvested at 24 hours post inoculation (hpi), LN and spleens harvested at 48 and 72 hpi, and LN, spleens and lungs harvested at 96 hpi.