Epitope approaches

Rachkov, A. Minoura, N. Recognition of oxytocin and oxytocin-related peptides in aqueous media using a molecularly imprinted polymer synthesized by the epitope approach. J Chromatogr A 2000, 889 (1 -1-2), 111 118. 

Development of a peptide vaccine is derived from the identification of the immunodominant epitope of an antigen (141). A polypeptide based on the amino acid sequence of the epitope can then be synthesized. Preparation of a peptide vaccine has the advantage of allowing for large-scale production of a vaccine at relatively low cost. It also allows for selecting the appropriate T- or B-ceU epitopes to be included in the vaccine, which may be advantageous in some cases. Several vaccines based on peptide approaches, such as SPf66 (95) for malaria and an HIV-1 peptide (142) have been in clinical trials. No peptide vaccines are Hcensed as yet. 

The development of class-selective antibodies is another approach to multi-analyte analysis. The analyst may design haptens that will generate antibodies that recognize an epitope common to several compounds, as explained above for the analysis of pyrethroids by measuring PBA. Other examples of class-selective immunoassays that have been developed are mercapturates," glucuronides, pyrethroids, organophosphate insecticides, and benzoylphenylurea insecticides." ... 

Pellequer, J. L., Westhof, E. andVanRegenmortel, M. H. V. (1994), Epitope prediction from primary structure of proteins , in G. B. Wisdom (Ed.), Peptide Antigens A Practical Approach, IRL Press, Oxford, UK, pp. 7-25. 

The use of pairs of matched spectral variants of GFP, like cyan and yellow or GFP and mRed, to differentially tag proteins and look for interactions, is now in routine use. The approach can be readily applied to homodimerization of molecules that differ only by their living color or epitope tag. For example, homomultimer-ization of a viral coat protein can be observed by imaging a mixture of cyan and yellow tagged homomeric molecules [46], whereas oc-synuclein stacking can be detected by utilizing a-synuclein transcripts that encoded different epitope tags for detection by immunostaining [47],... 

To study the role of lysine residues in susceptibility to formalin fixation, the amino acid composition of immunoreactive peptides (to various monoclonal antibodies) was studied. Each peptide was evaluated to determine if immu-noreactivity was lost after formalin fixation. Formalin sensitivity was correlated with the peptides amino acid composition. The first step in the method is biopanning from a peptide combinatorial library with a monoclonal antibody. The peptides that bind to the antibody were tested for their sensitivity to formalin fixation. Some peptides remain immunoreactive whereas others do not. The peptides were then sequenced to look for differences between those that were sensitive to formaldehyde versus those that were not. The goal was to find whether there is a particular amino acid that is present in formalin-sensitive epitopes but absent in formalin-resistant epitopes, or vice versa. An advantage of this approach is that it is open-ended, without excluding any amino acids. 

Synthetic haptens mimicking some critical epitopic structures on larger macromolecules are often conjugated to carriers to create an immune response to the larger parent molecule. For instance, short peptide segments can be synthesized from the known sequence of a viral coat protein and coupled to a carrier to induce immunogenicity toward the native virus. This type of synthetic approach to immunogen production has become the basis of much of the current research into the creation of vaccines. 

A number of approaches may be adopted in an attempt to reduce or eliminate protein im-munogenicity. Protein engineering (Chapter 3), for example, has been employed to humanize monoclonal antibodies (Chapter 13). An alternative approach entails the covalent attachment of polyethylene glycol (PEG) to the protein backbone. This can potentially shield immunogenic epitopes upon the protein from the immune system. 

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