Dr. Hyeog Sun Kwon from the Iowa State University Department of Entomology will be presenting a seminar as part of the Department of Entomology's spring semester seminar series.
Abstract. Malaria is one of most devastating human diseases. Caused by parasites of the genus Plasmodium, malaria is transmitted solely through the bite of anopheline mosquitoes. In 2015 alone, malaria caused approximately half a million deaths, predominantly in sub-Saharan Africa. The immunological interactions between mosquito vectors and malaria parasites is a key determinant of vector competence. Therefore, a detailed understanding of the immune molecules capable of influencing parasite development in the mosquito can provide opportunities to develop chemical and genetic approach to disrupt disease transmission. Mosquito innate immunity is comprised of both cellular and humoral factors that efficiently protect hosts from pathogens. Immune cells known as hemocytes play critical roles in killing invading pathogens by phagocytosis, encapsulation and nodulation. However, little is known about their respective contributions to malaria parasite infection. To address the immune responses mediated by phagocytic granulocytes on parasite development, we treated Anopheles gambiae mosquitoes with clodrosome (liposomal clodronate), a chemical widely used for macrophage depletion in mammalian studies. We observed that the phagocytic granulocyte population was significantly reduced in clodrosome treated mosquitoes. Consequently, in subsequent experiments, the depletion of mosquito granulocytes impeded immune defenses to bacterial and malaria parasite infections, causing high mortality and increased parasite survival. Furthermore, we reveal that the immune responses mediated by granulocytes shortly after parasite infection (<24h) are the most critical to the establishment of immune responses that limit malaria parasite survival. To our knowledge, this study provides the first definitive insights into our understanding of mosquito cellular immune responses to malaria parasite infection, and serves as an important tool to advance the study of phagocytic cells in other insect vectors.