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Baculoviruses infect invertebrates (mainly insects), cause no human disease, and cannot even replicate in vertebrate organisms. Nevertheless, baculoviruses are widely studied in labs all over the world and are considered to be important for several reasons. One reason is purely academic: baculoviruses have some unique properties that make them especially interesting. The other reasons are more practical. First, baculoviruses have been developed as eukaryotic expression vectors that can produce foreign proteins at high levels in insect cells. Second, baculoviruses hold promise as biological insecticides which, unlike chemical insecticides, are highly specific for insect pests and do not contaminate the environment.
The baculovirus expression system is already being widely used in research and biotechnology and it has been used to produce two FDA-licensed, commercial human vaccines. Nevertheless, further research is needed. Our group studies protein biosynthesis and processing in this system. We use biochemistry, cell biology, molecular genetics, and virology to determine how proteins are produced, modified, and localized during infection at the molecular level. Most of our recent research has focused on glycoproteins, which reflects our emphasis on the glycobiology of the baculovirus-insect cell system.
The glycoproteins are a major class of macromolecules that includes many important proteins, such as immunoglobulins, cytokines, and receptors. Glycoproteins have a polypeptide backbone and at least one covalently linked oligosaccharide, or glycan. Eukaryotic cells have elaborate biosynthetic pathways for glycoprotein production. The best known pathway begins with the transfer of a large glycan precursor to a polypeptide chain and proceeds with processing of the precursor to its final form. Glycan processing involves a sequential series of trimming and elongation reactions carried out by enzymes localized along the cellular secretory pathway. Different types of organisms have different sets of glycan processing enzymes. Thus, the N-glycans found on glycoproteins produced by distantly related organisms usually have different structures.
The glycans on recombinant glycoproteins produced by baculovirus expression vectors are synthesized by host cell machinery. And, insect cells cannot process N-glycans as extensively as their mammalian counterparts. Specifically, they fail to produce recombinant products containing glycans with terminal sialic acids. This is a serious problem because the absence of sialic acids on a recombinant glycoprotein produced in the baculovirus-insect cell system can directly or indirectly diminish its function, relative to the native product.
We have been studying protein N-glycosylation pathways in the baculovirus-insect cell system for over twenty years. Our major contributions include biochemical characterization of the insect cell N-glycosylation pathway, cloning of insect cell genes encoding enzymes involved in N-glycan processing, and detailed characterization of these gene products. Our ultimate goal is to elucidate pathways for glycoprotein biosynthesis and processing at a detailed molecular level in this system. This work has yielded valuable and interesting results and has helped define the differences between insect and mammalian protein glycosylation pathways. In addition, we have used these results to develop cellular and insect transgenesis strategies, which have yielded new, "glycoengineered" expression systems that can produce more authentic recombinant glycoproteins. This has led to several patents, commercialization of new expression vectors and cell-based expression platforms created by our group, and the establishment of a new Wyoming biotechnology company, GlycoBac, LLC, which will allow us to refine our glycoengineering efforts. Currently, we are evaluating the efficacy of the new expression systems developed through these efforts for the production of vaccines, therapeutic antibodies, and clinical diagnostic tests.
The interdisciplinary nature of our research and its direct practical applications can provide outstanding training and downstream career opportunities for all members of this lab. Each person will gain experience in virology, biochemistry, cell biology, molecular genetics, and the emerging field of glycobiology. In addition, everyone in the group is expected to address significant questions rigorously, to present their results at scientific conferences, and to publish in leading journals. The baculovirus-insect cell system is widely used and the new knowledge and research tools developed in this lab are widely recognized in both academic and industrial research circles. Hence, scientists with training and publications from our group have broad downstream career opportunities in either academic or industrial labs. We are constantly seeking talented and motivated scientists at all levels to join our group and help us to continue to explore this rich and interesting system. If you are one of those scientists and would like to join us, please contact Don Jarvis (email@example.com; 307-766-4282) anytime.(Last update 07/21/2011)