Persistent infection of C3H/HeJ mice by Ehrlichia chaffeensis
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1Department of Tropical Public Health, Harvard School of Public Health, Boston MA 02115, USA.
Abstract:
Description of the pathobiology of the recently described zoonotic agent of human ehrlichiosis (Ehrlichia chaffeensis) would be greatly facilitated by the availability of a convenient experimental animal model of infection. We determined whether C3H/HeJ mice could sustain persistent infection by this predominantly monocyte-inhabiting rickettsia. Such mice rapidly produced an intense specific IgG response upon inoculation of ehrlichiae, and high titers were demonstrable for more than 6 months thereafter. Ehrlichiae were reisolated from the peripheral blood and spleen of 1 mouse at day 11 after inoculation. DNA of E. chaffeensis was more frequently detected within these tissues by polymerase chain reaction. Other candidate rodent models appeared to be poor hosts for this pathogen. About half of intact and virtually all splenectomized white-footed mice that were inoculated seroconverted. Sera from inoculated voles and hamsters did not react to antigens of E. chaffeensis. 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.
Insights
C3H/HeJ mice can sustain persistent Ehrlichia chaffeensis infection, showing a strong immune response for over six months. This makes them a valuable animal model for studying human ehrlichiosis.
Area of Science:
- Infectious Diseases
- Immunology
- Zoonotic Pathogens
Background:
- Human ehrlichiosis is caused by Ehrlichia chaffeensis, a zoonotic agent.
- Understanding its pathobiology requires a suitable experimental animal model.
- Current models for studying Ehrlichia chaffeensis are limited.
Purpose of the Study:
- To determine if C3H/HeJ mice can sustain a persistent infection with Ehrlichia chaffeensis.
- To evaluate C3H/HeJ mice as a potential animal model for ehrlichiosis research.
- To assess other rodent species as potential hosts for Ehrlichia chaffeensis.
Main Methods:
- Inoculation of C3H/HeJ mice with Ehrlichia chaffeensis.
- Monitoring specific IgG antibody responses over time.
- Reisolation of Ehrlichia chaffeensis from peripheral blood and spleen.
- Detection of Ehrlichia chaffeensis DNA using polymerase chain reaction (PCR).
- Testing other rodent models including white-footed mice, voles, and hamsters.
Main Results:
- C3H/HeJ mice developed a rapid and intense specific IgG response lasting over 6 months.
- Ehrlichia chaffeensis was reisolated from infected C3H/HeJ mice.
- Ehrlichia chaffeensis DNA was frequently detected in C3H/HeJ mouse tissues via PCR.
- Other tested rodent models showed poor susceptibility to Ehrlichia chaffeensis infection.
- Splenectomized white-footed mice showed higher seroconversion rates than intact mice.
Conclusions:
- C3H/HeJ mice become persistently infected with Ehrlichia chaffeensis.
- C3H/HeJ mice represent a useful experimental model for studying the immune response to Ehrlichia chaffeensis.
- This model will facilitate research into the pathobiology of human ehrlichiosis.