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Fig 4. Simultaneous in vivo biphotonic monitoring of pneumococcal meningitis and the accompanying neuronal injury in live transgenic mice. Streptococcus pneumoniae engineered for bioluminescence (lux) was used for direct visualization of disease progression. Host response was monitored in transgenic mice containing an inducible firefly luciferase (Fluc) reporter gene under transcriptional control of the mouse glial fibrillary acidic protein (GFAP) promoter. On the basis of the different spectra of light emission and substrate requirements for Fluc and luc, it is possible to monitor separately the 2 reporters by using a highly sensitive in vivo imaging system. In vivo (A and D) and ex vivo (B, C, E, and F) images of brains from transgenic mice with meningitis were obtained at 19 hours postinfection. A, B, and C show lux imaging and D, E, and F show Fluc imaging. Dorsal and ventral views of an ex vivo brain show the bacterial and GFAP signals individually. Much of the bacterial signal intensity comes from discrete patches, whereas GFAP is induced in the entire brain and there are different intensities of the bioluminescence signal intensity in certain regions of the brain. Note the strong bacterial signal intensity immediately surrounding the inoculation site in the anterior right frontal lobe. (Reprinted by permission from the American Society for Microbiology)
