Conserved epitopes on HIV-1, FIV and SIV p24 proteins are recognized by HIV-1 infected subjects

Abstract

Cross-reactive peptides on HIV-1 and FIV p24 protein sequences were studied using peripheral blood mononuclear cells (PBMC) from untreated HIV-1-infected long-term survivors (LTS; >10 y of infection without antiretroviral therapy, ART), short-term HIV-1 infected subjects not on ART, and ART-treated HIV-1 infected subjects. IFNγ-ELISpot and CFSE-proliferation analyses were performed with PBMC using overlapping HIV-1 and FIV p24 peptides. Over half of the HIV-1 infected subjects tested (22/31 or 71%) responded to one or more FIV p24 peptide pools by either IFNγ or T-cell proliferation analysis. PBMC and T cells from infected subjects in all 3 HIV⁺ groups predominantly recognized one FIV p24 peptide pool (Fp14) by IFNγ production and one additional FIV p24 peptide pool (Fp9) by T-cell proliferation analysis. Furthermore, evaluation of overlapping SIV p24 peptide sequences identified conserved epitope(s) on the Fp14/Hp15-counterpart of SIV, Sp14, but none on Fp9-counterpart of SIV, Sp9. The responses to these FIV peptide pools were highly reproducible and persisted throughout 2–4 y of monitoring. Intracellular staining analysis for cytotoxins and phenotyping for CD107a determined that peptide epitopes from Fp9 and Fp14 pools induced cytotoxic T lymphocyte-associated molecules including perforin, granzyme B, granzyme A, and/or expression of CD107a. Selected FIV and corresponding SIV epitopes recognized by HIV-1 infected patients indicate that these protein sequences are evolutionarily conserved on both SIV and HIV-1 (e.g., Hp15:Fp14:Sp14). These studies demonstrate that comparative immunogenicity analysis of HIV-1, FIV, and SIV can identify evolutionarily-conserved T cell-associated lentiviral epitopes, which could be used as a vaccine for prophylaxis or immunotherapy.

Keywords:

• CTL epitopes
• feline immunodeficiency virus
• FIV p24
• HIV p24
• SIV p24
• vaccine epitopes

Abbreviations:

• aa, amino acid
• AIDS, acquired immune deficiency syndrome
• ART, anti-retroviral therapy
• CFSE, Carboxyfluorescein succinimidyl ester
• CMI, cell mediated immunity
• CTL, cytotoxic T cell
• FIV, feline immunodeficiency virus
• GrzA, granzyme A
• GrzB, granzyme B
• HIV, human immunodeficiency virus
• HLA, human leukocyte antigen
• HERV, human endogenous retrovirus
• ICS, intracellular staining
• LANL, Los Alamos National Laboratory
• LTS, Long term survivors
• Nab, broadly neutralizing antibody
• PHA, phytohaemagglutinin
• SFU, spot forming units
• SIV, simian immunodeficiency virus
• ST, short term survivors

Disclosure of Potential Conflicts of Interest

JKY is the inventor of record on a patent held by the University of Florida and may be entitled to royalties from companies developing commercial products related to the research described in this paper.

Acknowledgments

The authors thank Melissa Volz, Shweta Kaushik, Melissa S. Abreu, and Sue H. Fujimura for their technical assistance, and Kaylynn Peter and Kathy Thoma for administrative assistance in organizing study subjects.

Funding

This work was supported by NIH R01-AI65276 (JKY and JAL), R01-AI30904 (JKY), and JKY Miscellaneous Donors Fund. This work was in part supported by the NIH/NCRR Clinical and Translational Science Award UL1 RR029890 (MHR) and TL1 TR00066 (SRR).

Supplemental Material

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