Characterization of Dugway Strain Host-Pathogen Interactions In Vivo.

is a Gram-negative, intracellular bacterium that causes the zoonosis Q fever. Among the many natural isolates of recovered from various sources, the Dugway group exhibits unique genetic characteristics, including the largest genomes. These strains were isolated during 1954-1958 from wild rodents from the Utah, USA desert. Despite retaining phase I lipopolysaccharide and the type 4B secretion system, two critical virulence factors, avirulence has been reported in a guinea pig infection model. Using guinea pig models, we evaluated the virulence, whole-cell vaccine (WCV) efficacy, and post-vaccination hypersensitivity (PVH) potential of a representative Dugway strain. Consistent with prior reports, Dugway appeared to be highly attenuated compared to a virulent strain. Indeed, Dugway-infected animals showed similarly low levels of fever, body weight loss, and splenomegaly like Nine Mile II-infected animals. When compared to a human Q fever vaccine, QVax, Dugway WCV exhibited analogous protection against a heterologous Nine Mile I challenge. PVH was investigated in a skin-testing model which revealed significantly decreased maximum erythema in Dugway Δ WCV-skin-tested animals compared to that of QVax. These data provide insight into this unique bacterial strain and implicate its potential use as a mutated WCV candidate.