Submitted to: Parasitology Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/11/2012
Publication Date: 6/27/2012
Citation: Macarisin, D., Obrien, C.N., Bauchan, G.R., Fayer, R., Jenkins, M.C. 2012. Immunolocalization of Delta-Giardin within the Ventral Disc in of Trophozoites and in cysts of Giardia duodenalis using the Multiplex Laser Scanning Confocal Microscopy. Parasitology Research. 111:241-248. Interpretive Summary: Giardia duodenalis is a bi-nucleate protozoan parasite that colonizes the upper small intestine of humans and animals causing diarrheal disease. To maintain infection within the small intestine, trophozoites, the replicative stage of the parasite, must attach to the epithelial layer of the gut and resist its peristaltic movement, bolus flow and continuous shedding of mucus and cells. A group of proteins called giardins within the ventral disc are believed to play a key role in Giardia virulence by mediating attachment to the epithelial cells of the host. It was suggested that delta- giardin plays the crucial role in trophozoite attachment to the intestinal epithelial cells and thus in Giardia virulence. The present study was undertaken to provide novel information on the disc structure by determining where delta- giardin localizes within the ventral disc of Giardia duodenalis. Herein we show for the first time that delta-giardin, even though it shares a great degree of colocolization with beta-giardin, is localized much more ventrally and therefore represents the actual adhesive side of the disc, whereas beta-giardin was not found on the ventral proximity of the disc. These new data indicate that delta-giardin is indeed the protein that makes intimate contact of the parasite with the intestinal epithelium of the host, potentially playing an important role in adhesion. These findings provide further support for the crucial role of the delta-giardin in Giardia adherence and highlight the potential of the giardins as promising targets for immunotherapy of clinical giardiasis.
Technical Abstract: Immunolocalization of alpha2-, beta- and delta-giardin in Giardia showed that in the trophozoites and cysts delta-giardin it strictly associated with the ventral disc. Optical sectioning of the ventral discs, together with quantitative colocalization of the immunoreactivity for delta- and beta-giardin, demonstrated that they are primarily localized to the ventral and dorsal sides of the disc, respectively.