LE3 .A278 2019

2019

Smith, Todd
Ferguson, Laura

Acadia University

Bachelor of Science

Honours

Biology

Biology

Mosquitoes, Culex territans, that take a blood meal from frogs heavily infected with Hepatozoon species suffer extensive damage to their digestive system and will typically die within four days after feeding on infected frogs. Dysregulation of the immune system may be contributing to this pathology; however, the immune response of C. territans during Hepatozoon infections is currently unknown. The objectives of this study were therefore to investigate the immune response of C. territans infected with Hepatozoon species of frogs, and to determine if overactive immune responses contribute to the pathology observed in these heavily parasitized mosquitoes. Two arms of the immune response that are thought to be involved in tissue damage, namely phenoloxidase activity, a proxy for melanisation, and the production of reactive oxygen species, were investigated in the midgut and haemocoel of uninfected and infected mosquitoes. Phenoloxidase activity decreased in the haemocoel of infected mosquitoes, suggesting that infection causes immunosuppression or host regulation of immunity. Conversely, the concentration of reactive oxygen species increased linearly with parasitaemiain the midgut, with a significantly higher concentration in heavily infected mosquitoes. Furthermore, heavily infected mosquitoes supplemented with antioxidants survived for longer periods post-feeding, suggesting that the production of reactive oxygen species is involved in the immune response, and that an overproduction of these molecules may contribute to mosquito mortality. These findings support our hypothesis that the immune system may be implicated in mosquito death, which could be due to a suppression of important immune responses, and to an overproduction of toxic molecules.

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https://scholar.acadiau.ca/islandora/object/theses:3322