A Novel Platform to Generate Synthetic Vaccine Candidates

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Title: A Novel Platform to Generate Synthetic Vaccine Candidates
Author: Case, Allison Carroll
Abstract: Vaccination remains the optimal means to prevent infectious disease by inducing antibodies that confer protective immunity against the pathogen in question [1 -3] . However , there remain viruses against which no effective vaccines exists including human immunodeficiency virus (HIV ) , West Nile Virus (WNV ) and hepatitis C virus (HCV ) . These viruses and others evade the immune response by undergoing rapid mutations in immunodominant epitopes [4 -6] . In addition , although they usually express conserved epitopes that are important for inducing neutralizing antibodies , in many cases these are not immunodominant . Traditional techniques in vaccine development have not been able to overcome these barriers for these and other viruses . Subunit and peptide vaccines are very safe but it is often difficult to identify the key epitopes needed to make them effective . New approaches to developing safe vaccines that induce broadly neutralizing antibodies are needed . Therefore , the long term goal of this project was to generate vaccine candidates for any virus for which a neutralizing antibody existed or could be made without prior knowledge of the protective epitope (s ) . Furthermore , we desired a way to administer these vaccine candidates safely and before exposure so as to induce neutralizing antibodies . To accomplish these goals , we began with the development of a platform to generate synthetic vaccine candidates . This platform consisted of 1 ) libraries of B cell epitopes or “shapes” prepared by displaying peptoid sequences on beads , 2 ) neutralizing monoclonal antibodies (MAbs ) to select the peptoids that bound to the antibody’s antigen -combining site , and 3 ) protein G dynabeads (PGDs ) and a magnet to bind and isolate antibody bound peptoid beads . Any sequences identified in the platform as potential B cell mimetics were further evaluated in two validation assays . The first consisted of a “color screening” assay to determine that the isolated on -bead peptoids were bound by antibody . The second confirmed that these peptoids would fail to be bound by antibody if an excess of the native antigen was added (i .e . that peptoid sequences were bound by the antibody’s binding sites ) . The major accomplishments to emerge from this study were 1 ) the creation of an optimized magnetic screening platform for the isolation of peptide B cell epitopes from an on -bead library , 2 ) a magnetic screening platform optimized for the isolation of peptoid B cell epitopes from a peptoid library , and 3 ) the identification of potential peptoid B cell epitope mimetics of FLAG peptide from a peptoid library using a MAb . Taken together , a sensitive , specific , and reproducible platform to identify vaccine candidates from a peptoid library was created . This platform is particularly important for viruses like HIV , HCV , and WNV where mutation makes foreknowledge of conserved , neutralizing epitopes difficult . Once sufficiently large and diverse libraries are created , the B cell epitope mimetics (vaccine candidates ) identifiable by this platform will have several advantages over their peptide counterparts . These peptoid -based vaccines are “safe” as there is no potential for reversion , they are less expensive and faster to synthesize than peptides , they are not dependent on the twenty amino acids , and the B cell epitopes identified with this platform can be conjugated to carrier in such a way that the multivalency and immunodominance can be controlled making this platform advantageous both to the generation of new vaccine candidates and in reformulating current vaccines . [Keywords : vaccine , novel , peptoid (s ) , mimetic (s ) , human immunodeficiency virus (HIV ) , platform , B cell epitopes , peptide]
URI: http : / /hdl .handle .net /2152 .5 /990
Date: 2012-07-10


A Novel Platform to Generate Synthetic Vaccine Candidates. Graduate School of Biomedical Sciences. Available electronically from http : / /hdl .handle .net /2152 .5 /990 .

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