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Michelo CM, Dalel JA, Hayes P, Fernandez N, Fiore-Gartland A, Kilembe W, Tang J, Streatfield C, Gilmour J, Hunter E. Comprehensive epitope mapping using polyclonally expanded human CD8 T cells and a two-step ELISpot assay for testing large peptide libraries. J Immunol Methods 2021; 491:112970. [PMID: 33529681 DOI: 10.1016/j.jim.2021.112970] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 11/30/2020] [Accepted: 01/18/2021] [Indexed: 02/01/2023]
Abstract
The genetic diversity of circulating HIV-1 strains poses a major barrier to the design, development and evaluation of HIV-1 vaccines. The assessment of both vaccine- and natural infection-elicited T cell responses is commonly done with multivalent peptides that are designed to maximally capture the diversity of potential T cell epitopes (PTEs) observed in natural circulating sequences. However, depending on the sequence diversity of viral subtypes and number of the HIV immunogens under investigation, PTE estimates, including HLA-guided computational methods, can easily generate enormous peptide libraries. Evaluation of T cell epitope specificity using such extensive peptide libraries is usually limited by sample availability, even for high-throughput and robust epitope mapping techniques like ELISpot assays. Here we describe a novel, two-step protocol for in-vitro polyclonal expansion of CD8 T cells from a single vial of frozen PBMC, which facilitated the screening 441 HIV-1 Gag peptides for immune responses among 32 HIV-1 positive subjects and 40 HIV-1 negative subjects for peptide qualification. Using a pooled-peptide mapping strategy, epitopes were mapped in two sequential ELISpot assays; the first ELISpot screened 33 large peptide pools using CD8 T cells expanded for 7 days, while the second step tested pool-matrix peptides to identify individual peptides using CD8 T cells expanded for 10 days. This comprehensive epitope screening established the breadth and magnitude of HIV-1 Gag-specific CD8 T cells and further revealed the extent of immune responses to variable/polymorphic epitopes.
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Affiliation(s)
- Clive M Michelo
- Zambia Emory HIV Research Project, B22/737 Mwembelelo, Emmasdale, Lusaka, Zambia
| | - Jama A Dalel
- Human Immunology Laboratory, International AIDS Vaccine Initiative, Imperial College London, London, United Kingdom
| | - Peter Hayes
- Human Immunology Laboratory, International AIDS Vaccine Initiative, Imperial College London, London, United Kingdom
| | - Natalia Fernandez
- Human Immunology Laboratory, International AIDS Vaccine Initiative, Imperial College London, London, United Kingdom
| | - Andrew Fiore-Gartland
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - William Kilembe
- Zambia Emory HIV Research Project, B22/737 Mwembelelo, Emmasdale, Lusaka, Zambia
| | - Jianming Tang
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Claire Streatfield
- Human Immunology Laboratory, International AIDS Vaccine Initiative, Imperial College London, London, United Kingdom
| | - Jill Gilmour
- Human Immunology Laboratory, International AIDS Vaccine Initiative, Imperial College London, London, United Kingdom
| | - Eric Hunter
- Zambia Emory HIV Research Project, B22/737 Mwembelelo, Emmasdale, Lusaka, Zambia; Emory Vaccine Center, Yerkes National Primate Research Center, 954 Gatewood Road NE, Atlanta, GA 30329, USA.
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