CCL2 and tularemia: Much work has been performed based on mouse models of tularemia in order to identify correlates of immunity (Cowley et al., 2007; Elkins et al., 2007; Cowley and Elkins, 2011; Ryden et al., 2012) and, again, secreted Th1-related cytokines, such as IFN-γ, TNF, and MCP-1, were observed and found to correlate to the protective efficacies obtained after immunization with attenuated mutants of F. tularensis subspecies tularensis (Ryden et al., 2012).