Imaging sporozoite cell traversal in the liver of mice.

Intravital fluorescence microscopy is an invaluable tool to study a dynamic phenomenon through its direct observation in living organisms. This technique can combine qualitative and quantitative analysis and has been capital to address long-standing questions about Plasmodium biology. Beyond a descriptive view of the parasite life cycle, the possibility to image infection in transgenic animals in which a specific cell type, molecule or process is labeled opens new possibilities to study host cell-parasite interactions in cellular and molecular details. An additional layer of refinement can be achieved with the use of fluorescent knockout mutants (parasite, mice, or both) to dissect the molecular basis of the process of interest. Here, we present a basic protocol for imaging the sporozoite behavior in the liver, emphasizing the detection of the sporozoite's ability to traverse host cells.