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Abstracts
Workgroup: Frontiers in Disease Research
Molecular Immune Responses of The Eastern Oyster Crassostrea virginica to the parasite Perkinsus marinus.
Principal Investigator(s):
Marta GŪmez-Chiarri, University of Rhode Island, gomezchi@uri.edu
Funding Period: 10/1/99 - 9/31/01 (extended to 5/1/02)
In order to elucidate the molecular responses of the oyster to parasitic infection, we used suppression subtractive hybridization to construct libraries of genes involved in the response of oysters to experimental infection by P. marinus. We also followed the time course of protease and antimicrobial activity in the plasma of oysters experimentally infected with this protozoan parasite. Experimental infection with P. marinus resulted in an increase of total protease activity at early time points after infection. This increase is accompanied by the detection of low molecular weight proteases from P. marinus,as well as changes in the profile of oyster metalloprotease activity in oyster plasma. Our results indicate that modulation of oyster proteases by P. marinus could be involved in the pathogenesis of Dermo disease. Two libraries of infection-related genes were constructed by subtracting pools of cDNA isolated from hemocytes of non-infected oysters to pools of cDNA from hemocytes of infected oysters. Differential screening analysis of 96 clones from each of the libraries confirmed the isolation of 22 non-infected -specific and 54 infected -specific clones. Approximately 17% of the differentially expressed clones from each library correspond to unique sequences. Most of these clones (about 80%) do not show similarity to other sequences in the genetic databases. The infected -specific library (genes up-regulated in the process of infection) included several clones coding for arginine kinase, a phosphotransferase involved in the utilization and storage of energy that has been proposed as a marker of disease and tissue damage. It also contained a clone coding for a fragment of histone 4. Histones, major structural components of the chromatin, have also been shown to possess antimicrobial activity. However, no antimicrobial activity was detected in the plasma of oysters experimentally infected with P. marinus.
IMPACTS and/or BENEFITS:
This research is one further step into elucidating the complex interactions occurring between the protozoan parasite P. marinus and its host, the Eastern oyster, at early time points after infection. We have developed libraries and tools that will allow the identification of a large amount of gene candidates for studies in oyster immunity and host-pathogen interactions. Tools and knowledge derived from this research could lead to the development of early clinical indicators of disease, a more precisely understanding of the mechanisms of pathogenesis of Dermo, and to the development of markers for the selection of disease resistant strains of oysters.
PROJECT PUBLICATIONS:
MuŅoz Ruiz P, Vance K, GŪmez-Chiarri M. Protease activity in the plasma of American oysters, Crassostrea virginica, experimentally infected with the protozoan parasite Perkinsus marinus. (submitted to J. Parasitology)
GŪmez-Chiarri M, MuŅoz, P, Humbyrd C, Dorrington T. Antimicrobial activity in the plasma of American oysters, Crassostrea virginica, experimentally infected with the protozoan parasite Perkinsus marinus. (in preparation).
GŪmez-Chiarri M., MuŅoz. P., Dorrington T., Dellaporta S. Differential gene expression in hemocytes of American oysters, Crassostrea virginica, in response to experimental infection with the parasite Perkinsus marinus. (in preparation).
GŪmez-Chiarri M, MuŅoz. P. Differential gene expression in Eastern oysters, Crassostrea virginica, experimentally infected with Perkinsus marinus. International Conference on Shellfish Restoration. Charleston, South Carolina, USA, 2002 (conference proceedings).
MuŅoz P, GŪmez-Chiarri M. Protease activity in the eastern oyster Crassostrea virginica after experimental infection with the protozoan parasite Perkinsus marinus. J Shellfish Res 21(1):376 (Proceedings of the National Shellfisheries Association Meeting 2002).
MuŅoz P*, GŪmez-Chiarri M. Study of the immune response of the Eastern oyster Crassostrea virginica to the parasite Perkinsus marinus. European Association of Fish Pathologists, Dublin, Ireland 2001 (conference proceedings).
GŪmez-Chiarri M, MuŅoz P. Molecular immune responses of the Eastern oyster to the parasite Perkinsus marinus. International Conference on Shellfish Restoration. Hilton Head, South Carolina, USA, 2000 (conference proceedings).
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