Developing a High-throughput Screening Method for Identification and Validation of T Cell Epitopes Based Upon the Mass Spectral Analysis of Antigens Bound to Class II HLA-DR Constructs

Unmet Need: 
Rational design of immunotherapeutics and biologics relies on clear knowledge of the immunodominant epitopes of antigens or autoimmunogenic epitopes of therapeutic proteins in order to optimize drug development.  Immunodominance is defined as restricted responsiveness of T cells to a few selected epitopes from complex antigens.  Current methods for identifying kinetically stable peptide-MHC complexes are in many cases inadequate for a number of reasons.  Dr. Sadegh-Nasseri has developed a new tool for the identification of physiologically relevant helper T cell epitopes from antigens.

Value Proposition:
The MHC Type II immunodominance assay is capable of identifying the immunodominant epitopes in model antigens or therapeutic proteins, which can streamline the development and/or reduce the cost of vaccine or biologic therapy production.

Technical Details:
Dr. Sadegh-Nasseri established a cell-free antigen processing system composed of defined proteins: human leukocyte antigen-DR1 (HLA-DR1), HLA-DM and cathepsins. Their reductionist system successfully identified known the physiologically selected immunodominant epitopes of two model antigens: hemagglutinin-1 (HA1) from influenza virus (A/Texas/1/77) and type II collagen (CII). When applied for identification of new epitopes from a recombinant liver stage antigen of malaria falciparum (LSA-NRC) or HA1 from H5N1 influenza virus (‘avian flu’), the system selected single epitopes from each protein that were confirmed to be immunodominant by their capacity to activate CD4+ T cells from H5N1-immunized HLA-DR1–transgenic mice and LSA-NRC–vaccinated HLA-DR1–positive human volunteers. The system has successfully been applied to multiple antigens including several proteins of HIV, thyroglobulin (target Antigen for Hashimoto's thyroiditis), and Peptidylarginine Deiminase 4 (PAD4) a target Ag in Rheumatoid Arthritis [1-3].
Importantly, Dr. Sadegh-Nasseri’s laboratory has demonstrated that immunodominance of an epitope is not absolute, and can change with the slightest modifications to an immunogen, such as addition of a spacer or a tag. Determination of the immunodominant epitope of a candidate therapeutic protein antigen can only be possible by the use of the above cell free reductionist system [4].
 

1. Nature Medicine, Vol. 16 No. 11, Nov. 2010 pp. 1333-1341
2. Nature Communications, Nov. 2014, DOI: 10.1038/ncomms6369
3. J. Proteome Res. 2017, 16, 355−365, DOI: 10.1021/acs.jproteome.6b00617
4. Nature.com/ Scientific Reports | 7:46418 | DOI: 10.1038/srep46418

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