The oyster is endowed with efficient immune mechanisms that are successful in fighting most infectious diseases. The protozoan parasite Perkinsus marinus, however, causes Dermo disease in oysters and is responsible for the catastrophic decline of oyster populations and damage to the estuarine ecosystem along the Atlantic and Gulf coasts of North America. In invertebrate and vertebrate species, recognition of microbial pathogens is achieved in part by carbohydrate-binding proteins named lectins. The recent discovery of a lectin (CvGal) that binds to pathogenic bacteria, microalgae, and the parasite P. marinus, has led to the hypothesis that CvGal represent a mechanism for recognition of pathogens and algal food, and that this defense and feeding mechanism is subverted by P. marinus to gain entry into the host. This project will test this hypothesis by characterizing CvGal and other related proteins in the oyster and investigating the biological role(s) of CvGal within the context of immune defense, feeding, and host-parasite interactions. By thoroughly investigating CvGal and other galectins in the oyster, novel insight will be gained into yet undescribed biological functions of lectins in immune and feeding functions, and a more thorough understanding of entry mechanisms of intracellular parasites of medical and veterinary relevance. Given the regional relevance of oyster disease, this project may contribute to novel intervention strategies to restore natural and farmed oyster populations. The oyster is also well suited for classroom integration of fundamental scientific principles of immune recognition and host-parasite biology. This project will involve the participation of undergraduates and high school students and teachers mostly from underrepresented minorities from the Baltimore area, both as interns at the bench and in the classroom, through partnerships with SciTech, an affiliated educational program located at the Center of Marine Biotechnology, and training programs such as ExPERT (NSF), Chesapeake Teacher Research Fellowship (NOAA), Living Classrooms, Ingenuity, Baltimore Community College, and mentorship programs from Howard and Baltimore Counties.
Normal 0 false false false EN-US X-NONE X-NONE Project Outcomes The protozoan parasite Perkinsus marinus causes "Dermo" disease in the eastern oyster, and is responsible for the catastrophic decline of natural and farmed oyster populations. Because oysters are filter-feeders that maintain the quality of the environmental water, their decline has also caused severe damage to the estuarine ecosystem along the Atlantic and Gulf coasts of North America. Intellectual merit Oysters, like all shellfish, lack antibodies and recognition of microbial pathogens is achieved, at least in part, by carbohydrate-binding proteins named lectins. In the oyster we have identified two galectins (which we named CvGal1 and CvGal2) that bind to pathogenic bacteria, microalgae, and most importantly, to the parasite P. marinus. This finding led us to hypothesize that the oyster galectins represent a mechanism for (a) recognition of microbial pathogens and algal food, and (b) that this defense and feeding mechanism is subverted by P. marinus to gain entry into the host. The major goal of the project was to test this hypothesis, and we implemented molecular, biochemical, biophysical, structural and cell biology approaches to characterize the genes, proteins, structural aspects, and the biological roles of CvGal1 and CvGal2. For the latter, we used multiple state of the art approaches to analyze the binding properties of CvGal1 and CvGal2, for the identification and characterization of the structures recognized on the parasite surface and on the phagocytic oyster cells, and to assess the functional properties of CvGal1 and CvGal2 in facilitating entry of the parasite. By thoroughly analyzing the structural and ligand-binding properties of CvGal1 and CvGal2, and their biological roles we gained significant knowledge about yet un-described biological functions of galectins in immune functions, and a more thorough understanding of novel host entry mechanisms of intracellular parasites. The results of this project have been published in high quality journals such as Nature Reviews Microbiol, Trends Parasitol., J. Immunol, BMC Genomics, Adv. Exp. Med. Biol., Biochemistry, Ann N Y Acad Sci., Front Immunol., and J Biol Chem. Two additional manuscripts are in preparation for publication in the near future. From a practical standpoint, and given the regional relevance of oyster disease, the new knowledge that this project provided is highly significant in that it will contribute to develop novel intervention strategies (such as the synthesis of inhibitors of CvGal1 and CvGal2 that will prevent or at least reduce parasite infection) to restore natural and farmed oyster populations, and environmental quality of the coastal environment in the USA. Broader impacts From the educational standpoint, the oyster-P. marinus model system is well suited for classroom integration of fundamental scientific principles related to immune recognition mechanisms and host-parasite biology. In addition of training of post-doctoral associates and junior faculty, several undergraduate and high school students and teachers, mostly from underrepresented minorities from the Baltimore/Washington area, participated throughout the funding period both as interns at the bench and in the classroom, through partnerships with SciTech, an affiliated educational program located at IMET, and training programs such as ExPERT (NSF), Baltimore Community College, and mentorship programs from Howard and Baltimore Counties. High school and undergraduate students participated as co-authors in conference papers, and the high school teachers developed teaching modules based on their experiences in the Lab.
