RESUMO
The rapid spreading of the newly emerged SARS-CoV-2 variant, B.1.1.7, highlighted the requirements to better understand adaptive immune responses to this virus. Since CD8+ T cell responses play an important role in disease resolution and modulation in COVID-19 patients, it is essential to address whether these newly emerged mutations would result in altered immune responses. Here we evaluated the immune properties of the HLA-A2 restricted CD8+ T cell epitopes containing mutations from B.1.1.7, and furthermore performed a comprehensive analysis of the SARS-CoV-2 specific CD8+ T cell responses from COVID-19 convalescent patients and SARS-CoV-2 vaccinees recognizing the ancestral Wuhan strain compared to B.1.1.7. First, most of the predicted CD8+ T cell epitopes showed proper binding with HLA-A2, while epitopes from B.1.1.7 had lower binding capability than those from the ancestral strain. In addition, these peptides could effectively induced the activation and cytotoxicity of CD8+ T cells. Our results further showed that at least two site mutations in B.1.1.7 resulted in a decrease in CD8+ T cell activation and a possible immune evasion, namely A1708D mutation in ORF1ab1707-1716 and I2230T mutation in ORF1ab2230-2238. Our current analysis provides information that contributes to the understanding of SARS-CoV-2-specific CD8+ T cell responses elicited by infection of mutated strains or vaccination. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=172 SRC="FIGDIR/small/437363v2_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@b9f2cdorg.highwire.dtl.DTLVardef@1f39e3dorg.highwire.dtl.DTLVardef@119c313org.highwire.dtl.DTLVardef@565388_HPS_FORMAT_FIGEXP M_FIG C_FIG
RESUMO
COVID-19 is caused by a newly identified coronavirus, SARS-CoV-2, and has become a pandemic around the world. The illustration of the immune responses against SARS-CoV-2 is urgently needed for understanding the pathogenesis of the disease and its vaccine development. CD8+ T cells are critical for virus clearance and induce long lasting protection in the host. Here we identified specific HLA-A2 restricted T cell epitopes in the spike protein of SARS-CoV-2. Seven epitope peptides (n-Sp1, 2, 6, 7, 11, 13, 14) were confirmed to bind with HLA-A2 and potentially be presented by antigen presenting cells to induce host immune responses. Tetramers containing these peptides could interact with specific CD8+ T cells from convalescent COVID-19 patients, and one dominant epitope (n-Sp1) was defined. In addition, these epitopes could activate and generate epitope-specific T cells in vitro, and those activated T cells showed cytotoxicity to target cells. Meanwhile, all these epitopes exhibited high frequency of variations. Among them, n-Sp1 epitope variation 5L>F significantly decreased the proportion of specific T cell activation; n-Sp1 epitope 8L>V variant showed significantly reduced binding to HLA-A2 and decreased the proportion of n-Sp1-specific CD8+ T cell, which potentially contributes to the immune escape of SAR-CoV-2.
RESUMO
Objective To explore the effects and mechanism of triptolide on proliferation and apoptosis of breast cancer MCF-7 cells.Methods MCF-7 cells were treated by different concentrations of triptolide.CCK-8 as-say was employed to detect the cell proliferation. The morphological changes were observed by an inverted micro-scope.The apoptosis rate was detected by flow cytometry.Expressions of Bcl-2,Bax,Survivin and Caspase-3 were measured by qRT-PCR and Western blot. Results Triptolide inhibited the proliferation of MCF-7 cells in a dose and time-dependent manner at a suitable range.Triptolide induced morphological changes and apoptosis.Triptolide also down-regulated Bcl-2 and Survivin expressions and up-regulated Bax and Caspase-3 expressions. Conclu-sions Triptolide inhibits proliferation and induces apoptosis of MCF-7 cells,and its mechanism may be related to down-regulation of Bcl-2 and Survivin expressions and up-regulation of Bax and Caspase-3 expressions.
