Below is a list and description of the ongoing projects in the Petersen Lab. If you are interested in learning more about any of these projects, you contact Dr. Petersen directly at, and/or one of the other lead researchers of the project listed below. To view the research that the Petersen Lab has published click here

Lyme Transmission-Blocking Vaccine Project

Estimates from the CDC indicate that over 300,000 people are diagnosed each year with LD. Ecological approaches to decrease B. burgdorferi burden in Ixodes ticks, and transmission to other hosts, are highly desired tools for use instead of the current ‘check for ticks’ approach. It is well established that after a vertebrate host is immunized with B. burgdorferi’ OspA they produce antibody that, upon bloodmeal ingestion by a feeding tick, kills B. burgdorferi within that tick. These are known as transmission-blocking vaccines (TBV). These tools, including TBV, have not been proven to decrease B. burgdorferi exposure in critical intermediate incidental host(s). In North America, both humans and dogs are incidental hosts of B. burgdorferi. We and others have demonstrated that dogs can serve as stand-in/proxies for human exposure to infected ticks. Hunting dogs are a robust model for this trial because they serve both as a proxy of an active outdoors incidental host (like people at high-risk of contracting LD) and are a conduit of ticks into domestic habitats, increasing human exposure. The goal of this work is to demonstrate that a commercial-grade reservoir targeted TBV alters B. burgdorferi infection prevalence in questing ticks, in endemic areas (MD) geographically distinct from the first field trial (NY).

To show proof-of-principle for an ecological disruption of Borrelia transmission, we propose to:
1) Establish the efficacy of a commercial-grade reservoir targeted transmission blocking vaccine (TBV) in reducing prevalence of B. burgdorferi in the tick vector and how it affects clinical disease in incidental hosts (dogs) in a five-year field study.
2) Use a Bayesian hierarchical statistical model to estimate how TBV treatment of infected ecosystems will alter human B. burgdorferi exposure.

These proposed studies are highly significant to public health as a field trial demonstration of a TBV that disrupts the enzootic transmission cycle of B. burgdorferi to incidental hosts. Furthermore, demonstration of reduced human (incidental host) Lyme disease will be performed through a stochastic Bayesian model that will provide critical evidence for a new tool to decrease environmental exposure to Lyme disease. This work innovates as a demonstration of an efficacious, easily distributable and inexpensive TBV that reduces B. burgdorferi prevalence in nymphal and adult ticks, as well as B. burgdorferi transmission from ticks to incidental hosts. Reduction of transmission of B. burgdorferi to incidental hosts as a result of TBV distribution will prove to be a paradigm-shifting strategy to reduce the burden of Lyme disease in veterinary and human populations. Findings from experiments proposed in this study will advance translational knowledge of B. burgdorferi vaccinology and will provide strong evidence regarding the possibility of TBV reducing the human health risk of exposure to Lyme disease across the United States.

If you are interested in learning more about this project, please contact:
Dr. Christine Petersen (
Julia Poje (

Leishmania Sarolaner Project

Dogs in the U.S. are infected with L. infantum from birth and treatment options often come with adverse side effects. There is a critical need for alternative methods of leishmaniosis control. Our preliminary data shows a connection between tick-borne co-infections (tick-borne pathogens) and canine leishmaniosis severity. In recent years, the range of US tick habitats has expanded and the incidence of tickborne pathogens such as Lyme disease, Ehrlichiosis, and Anaplasmosis has risen. The proposed work will determine the efficacy and applicability of using tick prevention to delay or prevent Leishmania disease progression in dogs. Our long-term goal is to use tick control combined with informed selective breeding, to eliminate leishmaniosis from U.S. dogs.

Through a randomized, controlled, trial, we will study how progression of leishmaniosis in dogs who develop tick-borne co-infections differs in comparison with those who remain seronegative. Starting with a group of asymptomatic Leishmania-infected dogs, we will prevent tick-borne co-infections in one group of dogs using sarolaner, a recently developed, oral, acaricide. Dogs will be randomized to either receive sarolaner or placebo. All dogs will continue to receive their current (limited and ineffectual) tick control as provided by the kennel at present.

If you are interested in learning more about this project, please contact:
Dr. Breanna Scorza (
Kurayi Mahachi (

Canine Lyme Disease NK/T cell Project

The understanding of how inflammation arises during Lyme disease (LD) and what immune cells are responsible for this inflammation is limited, both for human and canine disease. Better knowledge of which canine immune cells are associated with production of inflammatory cytokines as LD progresses and have greater abundance during acute disease vs. increased presence during resolution of (canine) LD would provide targets for both assessment of clinical progression as well as immunomodulation or therapy. These findings will have direct implications to human infection with tick-borne diseases as an added benefit of this research (One Health, dual purpose research).

CD8+ T cells, Natural Killer (NK) cells and the hybrid Natural Killer T (NKT) cells are all known for producing inflammatory mediators, or cytokines, particularly the classical inflammatory cytokine, interferon-gamma (IFN-γ). These cells, as the names imply, have the ability to remove or kill infected cells, a role first described during viral infection, but since then shown to be important in clearing other types of infection, as well as tumor cells. Roles of different inflammatory canine immune cells, particularly those implicated from study of murine models or human patients with LD (NK, NKT, T cells) in the immunopathology (NKp46+ or CD56+ T cells in human and mouse studies) or immune resolution (NK cells-human arthritis studies) during canine Borrelia infection have not been established.

Based on this gap in knowledge the objectives of this project is to:
1) Assess the phenotypes and functions of inflammatory NK and CD8+ T cells during three stages of canine Lyme disease.
2) Assess the number and overall percentage of inflammatory vs. regulatory NK and CD8+ T cells during acute canine tick-borne co-infection with Babesia spp, Ehrlichia spp and multiples thereof.

If you are interested in learning more about this project, please contact:
Dr. Breanna Scorza (

Here is a list of other ongoing projects that are still being developed, close to being finished, or is a project a sibling lab is working on with the help of the Petersen Lab.

India Non-Human Reservoir Study
US Leishmania Genetics Study / Leishmania Proteomics Project
Canine L. braziliensis Treatment Project
Brazil Anaplasma Project
Leishmania Canine Spleen Pathology Project