RESUMO
While SARS-CoV-2-specific T cells have been characterized to play essential roles in host immune protection in COVID-19 patients, few researches focus on the functional validation of T cell epitopes and development of vaccines inducing specific T cell responses. In this study, 120 CD8+ T cell epitopes from E, M, N, S and RdRp proteins were validated. Among them, 110 epitopes have not been reported previously; 110, 15, 6, 14 and 12 epitopes were highly homologous with SARS-CoV, OC43, NL63, HKU1, and 229E, respectively; 4 epitopes from S protein displayed one amino acid distinct from the current variants of SARS-CoV-2. Thirty-one epitopes restricted by HLA-A2 molecule were used to generate peptide cocktail vaccines in combination with Poly(I:C), R848 or polylactic-co-glycolic acid nanoparticles, which elicited robust specific CD8+ T cell responses in wild-type and HLA-A2/DR1 transgenic mice. Seven of the 31 epitopes were found to be cross-presented by HLA-A2 and H-2K/Db molecules. Unlike previous researches, this study established a modified cell co-culture system of DC-peptide-PBL using healthy donors PBMCs to validate the CD8+ T cell epitope on-silicon predicted; provided a library of CD8+ T cell epitopes restricted by a series of high-frequency HLA-A allotypes which covering broad Asian populations; identified the HLA-A cross-restrictions of these CD8+ T cell epitopes using competitive binding experiments with HMy2.CIR cell lines expressing indicated HLA-A molecules; and initially confirmed the in vivo feasibility of 9 or 10-mer peptide cocktail vaccines of SARS-CoV2. These data will facilitate the development of vaccines inducing antiviral CD8+ T cell responses.
RESUMO
<p><b>OBJECTIVE</b>To observe the immune reaction in the mixed culture of host lymphocytes with allogenic and host endothelial cells.</p><p><b>METHODS</b>The host epithelial cells and lymphocytes from burn patients and allogenic epithelial cells were mix-cultured in different ratios, so as to simulate the local immune micro-environment of host skin island in intermingled skin grafting. In addition, the cells from normal human subjects were also mix-cultured as control. The lymphocyte cpm values were detected by (3)H-TdR and HLA molecules and T cell subgroup were determined by immunohistological technique.</p><p><b>RESULTS</b>(1) The lymphocyte proliferation reaction could be effectively inhibited by the epithelial cells from burn patients but not from normal control. (2) The inhibition of host lymphocyte proliferation could not be mediated by the HLA-DQ molecules of epithelium from burn patients. (3) The positive expression rate of HLA-DR of epithelia from burn patients was evidently higher that that from normal control (P < 0.05), (4) The CD8 expression of lymphocyte in burn patients was significantly higher than that in normal control (P < 0.01), while the CD4 expression in burn patients was lower than that in normal control (P < 0.01). But there was no obvious difference of the CD3 expression between patients and normal subjects (P > 0.05).</p><p><b>CONCLUSION</b>The lymphocyte proliferation reaction could be obviously inhibited by the host epithelium, which might be related to the specific immune state of the host lymphocytes and epithelium of burn patients.</p>
