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Title:Intestinal delivery of heterologous peptides with lactobacilli
Author(s):Zhang, Luyu
Advisor(s):Miller, Michael
Department / Program:Food Science & Human Nutrition
Discipline:Food Science & Human Nutrition
Degree Granting Institution:University of Illinois at Urbana-Champaign
Heterologous protein
Oral tolerance
Abstract:Oral administration of autoantigen is a promising method to induce oral tolerance in autoimmune diseases, such as multiple sclerosis. Multiple sclerosis (MS) is a complex disorder of the central nervous system. MS is caused by destruction of several brain antigens in myelin. In order to increase the efficiency of oral tolerance induction, lactobacilli were developed as a tool to deliver heterologous protein into the gastrointestinal tract. Lactobacillus spp. are a potential delivery vehicle for oral antigens because of their generally regarded as safe (GRAS) status, ability to persist in the acidic environment of human gastrointestinal tract and also their health benefit to the host. The goal of this study was to utilize lactobacilli as a genetic tool for heterologous protein expression and display. Three strains of lactobacilli were selected, and they are L. acidophilus ATCC 4356, L. gasseri ATCC 33323, and L. salivarius ATCC 11741. Two strategies have been discussed in this thesis to develop lactobacilli delivery system. The first strategy developed genetically modified lactobacilli which express myelin epitopes from proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG). Two series of vectors has been constructed which direct the expression of these antigens either anchored to the cell wall or secreted into the environment. However, we only confirmed that PLP epitopes expressed from cell lysate of recombinant L. acidophilus, which contained plasmid with only secreted signal. We decided to develop the second strategy. The second strategy explored the non-covalent attachment of myelin epitopes to the cell wall of Lactobacillus spp. via cell wall binding domains. In this study, three non-covalent CWBD were selected including L. gasseri ATCC 33323 LysM domain-containing protein, L. gasseri ATCC 33323 Lysozyme M1, Bacterial SH3 domain and C-terminal membrane anchor domain of Lactococcus lactis subsp. cremoris MG1363 AcmA protein. Through working with these domains, we found that L. gasseri ATCC 33323 Lysozyme M1 – bacterial SH3 domain can successfully bind on the exterior cell surface to L. acidophilus ATCC 4356, L. gasseri ATCC 33323, and L. salivarius ATCC 11741. Therefore, SH3 domain may be a good tool for oral administration by binding heterologous epitopes to lactobacilli. In future study, myelin epitopes and SH3 domain fusion proteins need to be displayed on the cell wall surface of lactobacilli. An animal model of multiple sclerosis is also important to evaluate an immune response of lactobacilli delivery system.
Issue Date:2015-01-21
Rights Information:Copyright 2014 Luyu Zhang
Date Available in IDEALS:2015-01-21
Date Deposited:2014-12

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