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Published on: February 14, 2011
Experimental infection of the white-footed mouse with Borrelia burgdorferi
1Department of Pathobiology, University of Connecticut, Storrs 06268.
Abstract:
Laboratory raised white-footed mice (Peromyscus leucopus) were inoculated experimentally with live spirochetes (Borrelia burgdorferi), the etiologic agent of Lyme disease (borreliosis). Prior to inoculation, mouse sera were tested with an indirect fluorescent antibody test, and all mice were seronegative. All inoculated mice seroconverted. In tick transmission studies, immature stages of Ixodes dammini and Dermacentor variabilis attached and fed to repletion on mice, but only I dammini transferred spirochetes to uninfected mice. Mice were susceptible to oral infection and transmitted infection to each other through direct contact. Infection did not affect reproduction or development of young born from infected dams, nor did spirochetes appear in the tissues of neonates. Borrelia burgdorferi spirochetes were identified in the kidneys, liver, and spleen of infected mice by the use of the modified Steiner silver stain and a tissue indirect fluorescent antibody test. Spirochetes also were isolated in culture of the heart blood of 1 mouse. Regardless of the source of infection, no mice developed clinical signs or had any pathologic change resulting from infection. Spirochetes were always observed extracellularly within interstitial spaces. Antibody titers persisted for over 4 months in some mice and spirochetes were found in the tissues of 1 mouse that had been infected 1 year earlier.
Insights
White-footed mice infected with Borrelia burgdorferi, the Lyme disease agent, developed antibodies and harbored spirochetes. However, infection did not cause clinical signs or affect reproduction in these mice.
Area of Science:
- Veterinary Science
- Infectious Diseases
- Microbiology
Background:
- Lyme disease is a significant public health concern caused by Borrelia burgdorferi.
- Understanding the pathogenesis and transmission dynamics of Borrelia burgdorferi in animal reservoirs is crucial for disease control.
Purpose of the Study:
- To investigate the susceptibility of white-footed mice (Peromyscus leucopus) to Borrelia burgdorferi infection.
- To evaluate the role of different tick species in Borrelia burgdorferi transmission.
- To assess the impact of infection on mouse reproduction and identify sites of spirochete persistence.
Main Methods:
- Experimental inoculation of laboratory-raised white-footed mice with live Borrelia burgdorferi.
- Serological testing using indirect fluorescent antibody assay to confirm infection and seroconversion.
- Tick transmission studies using Ixodes dammini and Dermacentor variabilis.
- Histopathological examination and culture of mouse tissues to detect spirochetes.
- Monitoring of reproductive parameters and neonates for transplacental transmission.
Main Results:
- All inoculated mice seroconverted, indicating susceptibility to Borrelia burgdorferi.
- Only Ixodes dammini successfully transmitted spirochetes to naive mice.
- Mice transmitted infection through direct contact and oral routes.
- Borrelia burgdorferi persisted in kidneys, liver, and spleen for up to one year post-infection.
- No clinical signs or pathological changes were observed in infected mice, and reproduction was unaffected.
- Spirochetes were not found in neonates, suggesting no transplacental transmission.
Conclusions:
- White-footed mice are susceptible to Borrelia burgdorferi infection, developing antibodies and persistent infections without clinical disease.
- Ixodes dammini is an effective vector for Borrelia burgdorferi transmission to mice.
- Mice can serve as reservoirs for Borrelia burgdorferi, potentially contributing to enzootic transmission cycles.
- The lack of clinical signs and reproductive impact in mice highlights their role as asymptomatic reservoirs.
