Use of two-photon microscopy to study Leishmania major infection of the skin.

Intra-vital two-photon microscopy (2P-IVM) allows for in-situ investigation of tissue organization, cell behavior and the dynamic interactions between different cell types in their natural environment. This methodology has also expanded our understanding of the immune response against pathogens. Leishmania are protozoan intracellular parasites that have adapted to successfully establish infection within the context of an inflammatory response in the skin following transmission by the bite of an infected sand fly. The generation of fluorescent transgenic parasites coupled with the increased availability of different types of fluorescent transgenic reporter mice has facilitated the study of the host-parasite interaction in the skin, significantly impacting our understanding of cutaneous leishmaniasis. In this review we will discuss 2P-IVM in the context of Leishmania infection of the mouse ear skin and describe a simple and minimally invasive procedure that allows long-term imaging of this host-pathogen interaction.