Epitope Selection

Epitopes, also known as antigenic determinants, refer to specific amino acid groups or chemical groups in an antigen molecule that determine antigen specificity. The epitope represents an immunologically active region on the antigen molecule responsible for binding to the antigenic receptor on the surface of the antibody molecule or the immune cells. Thus, different epitopes determine the difference in antigen receptor binding, which is important for specific immunity studies.

As a reliable provider in the target identification, Creative Biolabs has years of research experience in the field of epitope screening on T cells or B cells and devotes to exploring advanced technologies to identify tumor-associated antigens (TAAs) and to develop peptide-based therapeutics, like vaccines. In particular, our expert team offers a wide range of conventional techniques and customized services for global clients to support their projects of challenging purposes.

Why do We Need to Select Epitope?

• An epitope is a critical part of the antigen. The antigen binds to the corresponding receptor on the cell surface via the epitope, thereby activating the lymphocyte and causing an immune response.
• Epitopes are the basis of protein antigenicity, besides, the property, number, and spatial configuration of epitopes determine the specificity of the antigen.
• The selection of antigenic epitopes is of great significance for the design of peptides with immunogenicity and neutralizing activity, novel vaccine molecules, tumor-associated antigen discovery and tumor therapy.

Epitope Selection Services at Creative Biolabs

Fig.1 Summary of epitope-screening method. (Sharma, 2019)

At Creative Biolabs, we have established a variety of antigen epitope selection services, including traditional and combined methods. These selection processes combine the use of an algorithmic database for epitope prediction, epitope peptides, major histocompatibility complex (MHC)-binding assays, and immunological functional analysis to enable clients to be able to correlate immunogenicity with the most advantageous epitopes.

Traditional antigen epitope identification and selection tools

Multi-technology combined with new methods

Furthermore, we’re skilled at screening epitopes for multiple species, including but not limited to phage, amino acids, and immune cells, especially T cells and B cells.

Epitope Selection of T cells

Since T cells mainly recognize linear epitopes on antigen molecules, overlapping peptides can be synthesized based on the obtained amino acid sequence, and then T cell epitopes can be further determined by detecting the activity of the polypeptide. Given the importance of cytotoxic T lymphocyte (CTL) epitopes in the immune system, Creative Biolabs uses MHC tetramer technology for epitope selection of antigen-specific T cells.

Epitope Selection of B cells

Take Dengue virus NS1 (DENV) as an example, which is an important non-structural protein that plays an important role in DENV replication and dengue infection. Creative Biolabs selects the epitope of DENV2-NS1 protein on multiple B cells by phage display peptide library technology.

Different Types of Epitopes

• Covered and uncovered epitopes - On the surface of certain antigen molecules, different epitopes are relatively separated, and each binds to a specific antibody, which does not affect each other, termed a non-coverage epitope. If an epitope binds to the corresponding antibody and affects the binding of another epitope to the antibody, it is called an overhang epitope.
• Functional and hidden epitopes - Epitopes located on the surface of the antigen molecule are easily recognized by the corresponding lymphocytes, and can directly initiate an immune response, referred to as a functional epitope. An epitope present inside an antigen molecule does not directly trigger an immune response, which is called a concealed epitope.

Table.1 Divided into B cell epitopes and T cell epitopes according to antigen receptor cell binding.

Our Advantages

• High sensitivity: detecting low-abundance (≤1%) antigen-specific T cells and B cells in the blood.
• High specificity: greatly increasing the specificity of TCR binding to MHC-antigen polypeptide complexes.
• Good stability: Test results with excellent consistency and repeatability.
• Variety/Individualization: customizable, synthetic specific antigenic peptide fragments, combined into various T cell-selective and B cell-selective MHC tetramers.
• Qualitative/Quantitative analysis: qualitative/quantitative analysis of antigen-specific T cell or B cell populations by flow cytometry and other tools.

Many antigens have a number of distinct epitopes on their surfaces. As a well-known supplier around the world, Creative Biolabs would like to introduce comprehensive TAA epitope selection methods and multiple epitope screening services on T cells and B cells. If you’re interested in our epitope selection-related services, please directly contact us for more details.

Reference

1. Sharma, G.; et al. Rapid selection and identification of functional CD8+ T cell epitopes from large peptide-coding libraries. Nature Communications. 2019, 10: 4553.

For Research Use Only.