LE3 .A278 2018

2018

Smith, Todd

Acadia University

Bachelor of Science

Honours

Biology

Biology

Previous research in our laboratory revealed that wild-caught green frogs heavily infected with intraerythrocytic Hepatozoon species are more attractive to mosquito vectors, Culex territans, than uninfected frogs. Although green frogs appear to tolerate these protozoan parasites, they may experience a stress response to infection, potentially suppressing the immune system. In particular, stress may affect production of epidermal antimicrobial peptides, which could lead to alterations in the microbiome. The objective of this study was to examine potential changes in the epidermal microbiome of green frogs infected with Hepatozoon species as a possible cause for the increased attraction of C. territans to heavily infected frogs. The first strategy involved sampling the epidermal microbiomes of 38 frogs that were collected from two ponds near Wolfville, NS. Analysis of the DNA sequence data from these samples revealed that the microbiome of green frogs varies among collection sites and dates, and that there were many changes among the microbiomes of frogs with different intensities of Hepatozoon species. The second strategy involved assessing the relative attraction of C. territans to bacteria plated from epidermal swabs from uninfected and infected green frogs. Analysis of these data revealed that C. territans prefers the plated bacteria isolated from the epidermis of heavily infected frogs. The third strategy involved performing leukocyte counts from blood films made from the 38 frogs. Heavily infected frogs were found to have higher neutrophil: lymphocyte ratios relative to lightly infected and uninfected frogs, suggesting that the corticosterone levels in heavily infected frogs are also elevated. These results suggest that Hepatozoon species may generate a stress response in green frogs that results in changes to the epidermal microbiome, facilitating transmission to its mosquito vectors.

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https://scholar.acadiau.ca/islandora/object/theses:2690