Design and synthesis of HLA-A*02-restricted Hantaan virus multiple-antigenic peptide for CD8⁺ T cells

Hantaan virus (HTNV) can cause hemorrhagic fever with renal syndrome (HFRS) in humans with severe morbidity and high mortality. Although inactivated HFRS vaccines are given annually for prevention in populations, China still has the highest number of HFRS cases and deaths worldwide. Consequently, vaccination for HFRS requires the development of novel, more effective vaccines. Epitope peptide vaccines have been developed rapidly in recent years and are considered a novel approach for the prevention of infection. Specifically, the multiple antigenic peptide (MAP) design with preferable immunogenicity can arouse a satisfactory immune response for vaccination. However, there are few reports on the design and evaluation of MAP for HTNV.

Three HLA-A*02-restricted 9-mer cytotoxic T lymphocyte (CTL) epitopes on HTNV glycoprotein and one HLA-A*02-restricted 9-mer CTL epitope on the HTNV nucleocapsid, which have been proven to be immunoprotective in our previous study, were selected for the design of HTNV MAP. A four-branched HTNV MAP was evaluated by the IFN-γ-secreting enzyme-linked immunospot assay and proliferation induction capacity of CD8⁺ T cells and compared with the single HTNV CTL epitope in 17 HLA-A*02⁺ patients with HFRS. The Mann-Whitney U test was used for comparison of parameters between different subject groups.

The macromolecular HTNV MAP was designed with a polylysine core and four radially branched single CTL epitope chains. Importantly, HTNV MAP could stimulate CD8⁺ T cell secretion of IFN-γ in HLA-A*02⁺ patients with HFRS. The frequency of IFN-γ-secreting CD8⁺ T cells in the MAP stimulation group was significantly higher than that in the single HTNV CTL epitope stimulation groups (P < 0.005). Meanwhile, the activity of IFN-γ-secreting CD8⁺ T cells in the HTNV MAP group was also higher than that of the single CTL epitope groups (P < 0.05). Moreover, there was a much stronger ability of HTNV MAP to stimulate CD8⁺ T cell proliferation compared with that of a single HTNV CTL epitope.

The designed HTNV MAP could induce CTL responses ex vivo and may be considered a candidate for the design and development of novel HTNV peptide vaccines.