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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #334756

Research Project: Detection and Control of Foodborne Parasites for Food Safety

Location: Animal Parasitic Diseases Laboratory

Title: Surface binding properties of aged and fresh (recently excreted) Toxoplasma gondii oocysts

item HARITO, JEMERE - Norwegian University Of Life Sciences
item CAMPBELL, ANDREW - Alere As
item PRESTRUD, KRISTIN - Norwegian University Of Life Sciences
item Dubey, Jitender
item ROBERTSON, LUCY - Norwegian University Of Life Sciences

Submitted to: Experimental Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2016
Publication Date: 3/19/2016
Citation: Harito, J.B., Campbell, A.T., Prestrud, K.W., Dubey, J.P., Robertson, L.J. 2016. Surface binding properties of aged and fresh (recently excreted) Toxoplasma gondii oocysts. Experimental Parasitology. 165:88-94.

Interpretive Summary: Toxoplasmosis caused by a single celled parasite,Toxoplasma gondii, continues to be a worldwide public health problem. Human toxoplasmosis accounts for an estimated one-fifth of all diagnosed foodborne infections in the United States, and one fifth of the economiccosts attributable to any foodborne pathogen. Pregnant women and their fetuses are exposed to elevated health risks. Humans become infected by eating under cooked meat from infected animals and food and water contaminated with oocyst. The detection of oocysts in environmental samples is a major problem because of the few oocysts present. In the present study authors developed a monoclonal antibody against the oocyst wall that can distinguish between live and dead oocysts. These results will be of interest to parasitologists and biologists.

Technical Abstract: The surface properties of aged (stored for 10 years) and fresh (recently excreted) oocysts of Toxoplasma gondii were investigated using monoclonal antibody (mAb) and lectin-binding assays. Fresh oocysts bound a wall-specific mAb labeled with fluorescein isothiocyanate while aged oocysts did not. In contrast, the walls of aged oocysts bound a lectin (wheat germ agglutinin, WGA), but not the walls of fresh oocysts. Exposure of oocysts to detergent solutions had no effect on the binding properties of the walls of both aged and fresh oocysts, nor did exposure to trypsin. However, exposure of fresh oocysts to acidified pepsin enabled labeling of the walls with WGA, presumably due to the relevant moieties on the oocyst walls becoming exposed. WGA binding, but not mAb binding, was partially abrogated with periodate exposure. These findings reveal a significant difference in the binding properties of oocyst walls from “aged” and “fresh” oocysts. The results are of relevance when considering technologies for isolating or detecting T. gondii oocysts in environmental samples based on oocyst surface properties, as used for other protozoan parasites. Studies involving characterization of the carbohydrate compositions and surface antigens of the oocyst walls of T. gondii at various ages could provide further elucidation of the mechanisms by which the binding occurs. Our results suggest the possibility of developing a WGA-based separation procedure for isolating Toxoplasma oocysts from environmental matrices, in which pepsin pre-treatment would be