HTRA1 and scrub typhus: The establishment of the strong cell-mediated immune response in rhesus macaques (measured by a 47kDa htrA peptide-pool), is further evidence for the suitability in vaccine evaluations, as IFN-γ and type-1 immune responses have been associated with protection from O. tsutsugamushi infections in animal models, and strong IFN-γ responses to O. tsutsugamushi infection have been associated with acute scrub typhus in humans [3, 4, 12, 13, 21, 22, 38].