PT - JOURNAL ARTICLE AU - Jose Thekkiniath AU - Nicole Kilian AU - Lauren Lawres AU - Meital A Gewirtz AU - Morven M Graham AU - Xinran Liu AU - Michel Ledizet AU - Choukri Ben Mamoun TI - Evidence for vesicle-mediated antigen export by the human pathogen <em>Babesia microti</em> AID - 10.26508/lsa.201900382 DP - 2019 Jun 01 TA - Life Science Alliance PG - e201900382 VI - 2 IP - 3 4099 - https://www.life-science-alliance.org/content/2/3/e201900382.short 4100 - https://www.life-science-alliance.org/content/2/3/e201900382.full SO - Life Sci. Alliance2019 Jun 01; 2 AB - The apicomplexan parasite Babesia microti is the primary agent of human babesiosis, a malaria-like illness and potentially fatal tick-borne disease. Unlike its close relatives, the agents of human malaria, B. microti develops within human and mouse red blood cells in the absence of a parasitophorous vacuole, and its secreted antigens lack trafficking motifs found in malarial secreted antigens. Here, we show that after invasion of erythrocytes, B. microti undergoes a major morphogenic change during which it produces an interlacement of vesicles (IOV); the IOV system extends from the plasma membrane of the parasite into the cytoplasm of the host erythrocyte. We developed antibodies against two immunodominant antigens of the parasite and used them in cell fractionation studies and fluorescence and immunoelectron microscopy analyses to monitor the mode of secretion of B. microti antigens. These analyses demonstrate that the IOV system serves as a major export mechanism for important antigens of B. microti and represents a novel mechanism for delivery of parasite effectors into the host by this apicomplexan parasite.