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Experimental Ehrlichia chaffeensis infection in beagles
Xiao-Feng Zhang1, Jian-Zhi Zhang1, S Wesley Long1
1Departments of Pathology and Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases1 and Animal Resource Center2, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA.
Journal of Medical Microbiology
|October 9, 2003
Summary
Canine models show that dogs can carry Ehrlichia chaffeensis for 2-4 months post-infection without showing illness. This research highlights dogs as potential natural hosts for this pathogen.
Area of Science:
- Veterinary Medicine
- Infectious Diseases
- Molecular Biology
Background:
- Human monocytic ehrlichiosis is a significant zoonotic disease.
- Understanding Ehrlichia chaffeensis infection dynamics in natural hosts is crucial for disease control.
Purpose of the Study:
- To establish a canine model for persistent Ehrlichia chaffeensis infection.
- To investigate antigenic variation and host immune response in dogs infected with E. chaffeensis.
Main Methods:
- Two beagle dogs were inoculated with E. chaffeensis Arkansas strain.
- Monitoring included clinical signs, blood chemistry, antibody detection, and pathogen presence via culture and PCR for 6 months.
- Genetic analysis of the 120 kDa outer-membrane glycoprotein gene was performed.
Main Results:
- Dogs developed thrombocytopenia but remained afebrile.
- E. chaffeensis was culturable for up to 102 days and DNA detectable for up to 117 days.
- No genetic variation was observed in the studied gene; high antibody titers against multiple E. chaffeensis proteins were maintained.
Conclusions:
- Dogs can act as asymptomatic carriers of E. chaffeensis for 2-4 months.
- The canine model effectively replicates persistent E. chaffeensis infection without severe clinical signs.
- Dogs may serve as a significant reservoir host for Ehrlichia chaffeensis.