PERSISTENT INFECTION OF C3H HEJ MICE BY EHRLICHIA-CHAFFEENSIS/

Description of the pathobiology of the recently described zoonotic age nt of human ehrlichiosis (Ehrlichia chaffeensis) would be greatly faci litated by the availability of a convenient experimental animal model of infection. We determined whether C3H/HeJ mice could sustain persist ent infection by this predominantly monocyte-inhabiting rickettsia. Su ch mice rapidly produced an intense specific IgG response upon inocula tion of ehrlichiae, and high titers were demonstrable for more than 6 months thereafter. Ehrlichiae were reisolated from the peripheral bloo d and spleen of 1 mouse at day 11 after inoculation. DNA of E. chaffee nsis was more frequently detected within these tissues by polymerase c hain reaction. Other candidate rodent models appeared to be poor hosts for this pathogen. About half of intact and virtually all splenectomi zed white-footed mice that were inoculated seroconverted. Sera from in oculated voles and hamsters did not react to antigens of E. chaffeensi s. The C3H/HeJ mouse becomes persistently infected by this rickettsia, and may serve as a useful model for studies of the immune response to the agent of human ehrlichiosis.