Date of Submission

6-2020

Document Type

Thesis

Degree Name

Master of Science in Cellular and Molecular Biology

Department

Biology and Environmental Sciences

Advisor

Dr. Eva Sapi

Committee Member

Dr. Alireza Senejani

Committee Member

Dr. Carter Takacs

Keywords

Immersion assay, Immunohistochemistry staining, PCR methods, Reverse Transcription/Real Time PCR

MeSH

Borrelia burgdorferi, Zebrafish, Microinjections, Lyme disease

LCSH

Borrelia burgdorferi, Zebra danio, Infection--Animal models, Lyme disease, Physiological aspects

Abstract

Borrelia burgdorferi is a spirochetal bacterium which can cause Lyme disease. The infectious mechanisms of B. burgdorferi have been traditionally studied in different in vitro and in vivo systems. For example, various animal models have been used in understanding the transmission and pathogenesis of B. burgdorferi and the host immune response. Mice, dogs and Rhesus macaques have been instrumental in providing information about the pathogenesis of Lyme disease. However, they have many drawbacks such as high cost and long development time. The zebrafish, Danio rerio, has been recently established as an excellent model for infectious diseases for variety of bacterial pathogens, such as the spirochetal bacterium, Leptospira interrogans. This raised the question about whether the zebrafish could be a suitable animal model for B. burgdorferi infection. Therefore, the goal of this study was to evaluate whether zebrafish can be infected by B. burgdorferi and whether the B. burgdorferi can survive in zebrafish for long period of time. To introduce B. burgdorferi into the zebrafish, two different infection methods were used in this study: immersion assay and microinjection assay. The infected zebrafish were evaluated by monitoring physiological and behavioral parameters and B. burgdorferi presence was assessed by wholemount immunohistochemistry staining and different PCR methods. The results showed the zebrafish can be indeed infected with B. burgdorferi using any of the methods. Interestingly, findings also suggest that B. burgdorferi could affect the zebrafish physiology by altering the heart rate. To assess whether the zebrafish’s immune system would be able to clear the B. burgdorferi infection, Reverse Transcription/Real Time PCR was performed over a 2-month window post-infection. The results showed active B. burgdorferi transcription in all samples which suggest an ongoing infection. In summary, our study has provided evidence that B. burgdorferi infection model in zebrafish can be established by both immersion and microinjection methods. This study will widen the field at which the mechanism of B. burgdorferi infection can be studied in zebrafish as an animal model.

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