Bacterial Infection with Listeria monocytogenes in Mice and Subsequent Analysis of Antigen-Specific CD8 T Cell Responses.

Pathogens such as bacteria, viruses, fungi, or protozoa can cause acute and chronic infections in their hosts. The intracellular bacterium Listeria monocytogenes serves as a model pathogen to assess the molecular mechanisms regulating CD8 T cell activation, differentiation, and function. We set up an experimental workflow to investigate cell-intrinsic roles of the nuclear receptor NR2F6 in CD8 T cell memory formation upon Listeria monocytogenes (LmOVA) infection ( Jakic et al., 2021 ). The current protocol details how to cultivate ovalbumin-expressing LmOVA, infect naïve C57BL/6 mice with these bacteria and determine the bacterial load in host organs. Furthermore, we describe how to evaluate antigen-specific CD8 T cell responses and discriminate between short-lived effector and memory precursor cells in vivo following LmOVA infection (Figure 1). To assess CD8 T cell-intrinsic molecular mechanisms, we integrated an adoptive cell transfer (ACT) experiment of genetically modified naïve OT-I CD8 T cells into congenic hosts before LmOVA infection. Graphic abstract: Figure 1.Experimental workflow depicting the steps for infection of mice with Listeria and subsequent analysis of antigen-specific CD8 memory responses. Bacteria (ovalbumin expressing Listeria monocytogenes) are thawed and grown on lysogeny broth (LB) plates overnight (ON). A single colony is picked and grown in LB medium ON. Bacteria from the exponential growth phase are then injected into a C57BL/6 mouse via tail vein injection. Colony forming units (CFU) of the bacteria can be detected in the spleen on day 3 post injection. Antigen-specific CD8 T cell immune response can be investigated during the acute phase (d3 after infection), during the peak of the adaptive immune response (d7), the clearance phase (d26), or the memory phase (d70) by flow cytometry. Created with BioRender.com.