Real-time in vivo imaging of transgenic bioluminescent blood stages of rodent malaria parasites in mice

This protocol describes a methodology for imaging the sequestration of infected erythrocytes of the rodent malaria parasite Plasmodium berghei in the bodies of live mice or in dissected organs, using a transgenic parasite that expresses luciferase. Real-time imaging of infected erythrocytes is performed by measuring bioluminescence produced by the enzymatic reaction between luciferase and its substrate luciferin, which is injected into the mice several minutes prior to imaging. The bioluminescence signal is detected by an intensified charge-coupled device (I-CCD) photon-counting video camera. Sequestration of infected erythrocytes is imaged during short-term infections with synchronous parasite development or during ongoing infections. With this technology, sequestration patterns of the schizont stage can be quantitatively analyzed within 1-2 d after infection. Real-time in vivo imaging of infected erythrocytes will provide increased insights into the dynamics of sequestration and its role in pathology, and can be used to evaluate strategies that prevent sequestration.