An immunocompromised mouse model to infect Ixodes scapularis ticks with the relapsing fever spirochete, Borrelia miyamotoi.

Authors:
Geoffrey E Lynn
Geoffrey E Lynn
University of Minnesota
Wichita | United States
Nicole E Breuner
Nicole E Breuner
Centers for Disease Control and Prevention
Lars Eisen
Lars Eisen
Colorado State University
United States
Andrias Hojgaard
Andrias Hojgaard
Centers for Disease Control and Prevention
Washington | United States
Adam J Replogle
Adam J Replogle
National Center for Emerging and Zoonotic Infectious Diseases
Rebecca J Eisen
Rebecca J Eisen
Colorado State University
United States

Ticks Tick Borne Dis 2019 02 27;10(2):352-359. Epub 2018 Nov 27.

Centers for Disease Control and Prevention, United States. Electronic address:

The hard tick-borne relapsing fever spirochete, Borrelia miyamotoi, has recently gained attention as a cause of human illness, but fundamental aspects of its enzootic maintenance are still poorly understood. Challenges to experimental studies with B. miyamotoi-infected vector ticks include low prevalence of infection in field-collected ticks and seemingly inefficient horizontal transmission from infected immunocompetent rodents to feeding ticks. To reliably produce large numbers of B. miyamotoi-infected ticks in support of experimental studies, we developed an animal model where immunocompromised Mus musculus SCID mice were used as a source of B. miyamotoi-infection for larval and nymphal Ixodes scapularis ticks. Following needle inoculation with 1 × 10 spirochetes, the SCID mice developed a high spirochetemia (greater than 1 × 10 copies of B. miyamotoi purB per mL of blood) that persisted for at least 30 d after inoculation. In comparison, immunocompetent M. musculus CD-1 mice developed transient infections, detectable for only 2-8 d within the first 16 d after needle inoculation, with a brief, lower peak spirochetemia (8.5 × 10 - 5.6 × 10purB copies per mL of blood). All larval or nymphal ticks fed on infected SCID mice acquired B. miyamotoi, but frequent loss of infection during the molt led to the proportion infected ticks of the resulting nymphal or adult stages declining to 22-29%. The ticks that remained infected after the molt had well-disseminated infections which then persisted through successive life stages, including transmission to larval offspring.

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http://dx.doi.org/10.1016/j.ttbdis.2018.11.017DOI Listing
February 2019
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