Progress 07/15/03 to 07/14/08
Outputs OUTPUTS: Parasitoid wasps and flies are among the most important natural enemies of agricultural pests. This project focuses on the function of gene called glc1.8 expressed from Microplitis demolitor bracovirus (MdBV). Goals of this study were to characterize how MdBV and glc1.8 disable the insect cellular defense response by: a) characterizing recombinant Glc1.8 mutant proteins, b) bioassaying the immunosuppressive activity of these mutants, and c) examining how Glc1.8 interacts with pest insect molecules that regulate cellular immune defenses. Results of the study accomplished all major objectives of the project. Results of the study have also been disseminated through peer-reviewed scientific publications, national and international scientific meetings, and seminars presented in US and non-US universities. PARTICIPANTS: Participants: Dr. Markus H. Beck, Dr. Richard J. Suderman, Dr. Andrea Pruijssers, Ms. Shu Zhang, Ms. Jena Johnson, and Dr. Michael R. Strand TARGET AUDIENCES: Target audiences: Insect biology and insect pest management scientists, virologists, and immunologists with interests in insect-parasite or insect-pathogen interactions plus researchers studying the use of natural enemies for control of insect pest species. PROJECT MODIFICATIONS: No major changes in approach or goals were made during the course of the study.
Impacts Major outcomes of the study included: a) development of multiple recombinant mutant proteins of Glc1.8, b) bioassays that characterized the effects of different mutations on protein function, and c) completion of functional studies indicating that Glc1.8 interferes with the ability of specific insect pattern recognition receptors to bind their cognate ligands. Mutational analysis indicated that the most important functional domain for Glc1.8 is its N-glycosylated extracellular domain. Characterization of the carbohydrate moieties in this domain further identified that the majority of glycans present are high mannose or paucimannose sugars.
Publications
- Strand, M. R. 2008. Polydnaviruses: abrogation of the insect immune system. In: Encyclopedia of Virology, 2nd Ed. Volume 4, pp. 250-256. Elsevier, San Diego. Suderman, R. J., A. J. Pruijssers and M. R. Strand. 2008. Protein tyrosine phosphatase-H2 from a polydnavirus induces apoptosis of insect cells. J. Gen. Virol. 89, 5716-5721. Strand, M. R. 2008. The interactions between polydnavirus-carrying parasitoids and their lepidopteran hosts. In Molecular Biology of the Lepidoptera (M. Goldsmith and T. M Miller eds.) CRC Press, Boca Raton, FL. In press.
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Progress 07/15/06 to 07/14/07
Outputs Parasitoid wasps and flies are among the most important natural enemies of agricultural pests. This project focuses on the function of gene called glc1.8 expressed from Microplitis demolitor bracovirus (MdBV). Goals of this study are to characterize how MdBV and glc1.8 disable the insect cellular defense response. Progress during this year include production and characterization of multiple Glc1.8 mutants to assess domains required for functional activity. Analysis confirms that Glc1.8 is membrane bound due to a cytoplasmic anchor. Biological activity depends upon anchoring into the membrane, whereas the cytoplasmic tail is non-essential for function. Glycan analysis is still in progress but preliminary results indicate that all carbohydrate moities are N-linked. Expression of Glc1.8 interferes with multiple target cell receptors including Eater, dsC1 and alpha4/beta 1 integrin. Studies for the upcoming year will focus on completion of carbohydrate analyses and
receptor-glc1.8 interactions.
Impacts Deciphering host pathogen interactions is of utmost importance to the study of infectious diseases in mammals and insects. The proposed work will yield information of practical importance for the management of insect populations and on the function of immunosuppressive molecules that exhibit activity in multiple species. The interdisciplinary nature of the proposed project is also uniquely suited as a platform to train young scientists at the interface of parasitology, symbiosis, cell biology, and molecular processes.
Publications
- Webb, B. A., M. R. Strand, S. E. Deborde, M. Beck, R. S. Hilgarth, K. Kadash, J. A. Kroemer, K. G. Lindstrom, W. Rattanadechakul, K. S. Shelby, L. Thoetkiattikul, M. W. Turnbull, W. E. Barney, and R. A. Witherell. 2006. Polydnavirus genomes reflect their dual roles as mutualists and pathogens. Virology 347, 160-174.
- Pennacchio, F and M. R. Strand. 2006. Evolution of developmental strategies in parasitic Hymenoptera. Annu. Rev. Entomol. 51, 233-258.
- Wertheim, B., A. R. Kraaijeveld, E. Schuster, E. Blanc, M. Hopkins, S. D. Pletcher, M. R. Strand, H. C. J. Godfray, and L. Partridge. 2005. Genome wide expression in response to parasitoid attack in Drosophila. Genome Biol. 6: R94 (doi:10.1186/gb-2005-2005-6-11-r94).
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Progress 01/01/05 to 12/31/05
Outputs The goal of this project is to characterize a viral protein called Glc1.8 which functions as an inhibitor of the insect encapsulation response. The overall goal of this project is to characterize this protein and its immunosuppressive functions. Progress during the current year include mutational studies that identify essential domains for the anti-capsule forming activity of the protein. These studies also identified that glc1.8 inhibits phagocytosis by insect immune cells. Stably transformed cell lines have now been developed that express wild-type and mutant forms of the protein. Assays also identify cell surface and signaling pathways that glc1.8 inhibit.
Impacts This project focuses on basic science in the area of immunity and virology but our results provide important insights on how the insect immune system functions. Results also point to potential applications of this immunosuppressive molecule
Publications
- Beck, M. and M. R. Strand. 2005. Glc1.8 from Microplitis demolitor bracovirus induces a loss of adhesion and phagocytosis by insect High Five and S2 cells. J. Virol. 79, 1861-1870.
- Strand, M. R., M. H. Beck, M. D. Lavine, and K. D. Clark. 2005. Microplitis demolitor bracovirus inhibits phagocytosis by hemocytes from Pseudoplusia includens. Arch Insect Bich. Physiol. 61, 134-145.
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Progress 01/01/04 to 12/31/04
Outputs Parasitoid wasps and flies are among the most important natural enemies of insect agricultural pests. This project focuses on a gene called glc 1.8 expressed by a polydnavirus called MdBV. Progress during this year includes production of recombinant protein and transfected cell lines that stably express the Glc protein. Bioassays using these materials confirm that this molecule inhibits the ability of cells to bind foreign surfaces and to phagocytose pathogens. Additional mutagenesis studies identified functional domains of the protein required for adhesion blocking. Additional assays indicated that Glc proteins also block adhesion of immune cells in other insects and disrupt phagocytosis. These results identify a new class of virulence genes that suppress the insect immune system.
Impacts These results identify a new class of molecules that suppress the insect immune system. Characterization of these factors could yield new materials for development of pest insect control products.
Publications
- Webb B.A. and Strand M.R. 2005. The Biology and Genomics of Polydnaviruses. In Comprehensive Molecular Insect Science, Vol. 6 (Gilbert, L. I., Iatrou, and Gill, S. S., eds). Elsevier, San Diego, CA. pg. 323-360.
- Beck, M. and M. R. Strand. 2005. Glc1.8 from Microplitis demolitor bracovirus induces a loss of adhesion and phagocytosis by Insect High Five and S2 cells. J. Virol. 79, 1861-1870.
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Progress 01/01/03 to 12/31/03
Outputs Parasitoid wasps and flies are among the most important natural enemies of insect agricultural pests. Parasitoids are usually killed in non-permissive hosts by encapsulation, whereas parasitoids survive in permissive hosts by either possessing surface features that passively protect the parasitoid from being encapsulated or by immunosuppressing the host's encapsulation response. Immunosuppression is mediated by symbiotic polydnaviruses (PDVs) such as Microplitis demolitor bracovirus (MdBV). Prior studies identified the Glc gene as a key immunosuppressive protein encoded by MdBV. Specific objectives of this project are to: 1) Produce recombinant Glc proteins, 2) Bioassay the binding and adhesion-blocking activity of Glc proteins, and 3) Examine how Glc proteins interact with host molecules that regulate encapsulation. Progress during this year includes production of recombinant protein and transfected cell lines that stably express the Glc protein. Bioassays using
these materials confirm that this molecule completely inhibits the ability of cells to bind foreign surfaces and to phagocytose pathogens.
Impacts These results identify a new class of molecules that suppress the insect immune system. Characterization of these factors could yield new materials for development of pest insect control products.
Publications
- Kadash, K., J. A. Harvey and M. R. Strand. 2003. Cross-protection experiments with parasitoids in the genus Microplitis (Hymenoptera; Braconidae) suggest a high levelof specificity in their associated bracoviruses. J. Insect Physiol. 49: 473-482.
- Beck, M. and M. R. Strand. 2003. RNA interference silences Microplitis demolitor bracovirus genes and implicates glc1.8 in blocking adhesion of infected host cells. Virology, 314, 521-535.
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