Alexandra D.W. Akman Emma R. Dorfman Sarah A. Leppinen Heather S. Potkins


Introduction: Ixodes scapularis, the blacklegged tick, is responsible for the transmission of Lyme disease. Rising temperatures and shorter winter seasons, due to climate change, is resulting in the Northward expansion of tick range. This is correlated with the increasing prevalence of Lyme disease in Canada. This research protocol aims to address this issue by genetically mutating the blacklegged tick which is primarily responsible for the transmission of Borrelia burgdorferi, the bacterium that causes Lyme disease, in North America. The proposed mutation involves two gene knockouts: TROSPA and TRE31. The blacklegged tick mutant is predicted to be unable to transmit Lyme disease to the white-footed mouse, Peromyscus leucopus.

Methods: Mutated ticks will feed on the blood of Lyme positive mice and later naïve mice. The rate of Lyme disease transmission from mutated ticks will be compared to transmission rates in positive and negative wild type control groups. The statistical significance of the difference between these groups’ transmission rates will be evaluated by Student’s t-test with Fisher’s protected least significant difference test.

Results: Based on the results from literature testing each mutation independently, we predict our I. scapularis mutant, having both TROSPA and TRE31 gene knockouts, will be unable to transmit Lyme disease to the white-footed mouse.

Discussion: Unsuccessful transmission of Lyme disease from mutated ticks indicates that the TROSPA and TRE31 knockouts are effective in preventing B. burgdorferi from completing its lifecycle within the tick. Based on the expected results, the combined gene-knockout model presents a novel method to hinder the transmission of Lyme disease more effectively than previously investigated single gene knockouts.

Conclusion: This research protocol suggests a strategy to decrease the rate of Lyme disease amongst ticks, and thus humans. Future research could explore efficacies of knocking out other genes in combination with TROSPA or TRE31.

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Research Protocol