SARS-CoV-2 variant B.1.1.7 caused HLA-A2+ CD8+ T cell epitope mutations for impaired cellular immune response

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

CD8+ T cell epitope variations suggest a potential antigen presentation deficiency for spike protein of SARS-CoV-2

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.

Preparation and biological identification of monoclonal and functional antibody against human specific polypeptide FXYD6 / 重庆医学

Objective To study and prepare the monoclonal antibody library against human FXYD6 functional region,to screen the hybridoma cell lines secreting the monoclonal antibodies against intracellular or extracellular region of human FXYD6,and to identify the biological function of monoclonal antibody against extracellular domain.Methods FXYD6 functional region recombinant protein which did not contain the transmembrane region was prokaryotically expressed,purified,and FXYD6 recombinant protein was used to immunize BALB/c mice.Then splenocytes after immunization were fused with myeloma cells SP2/0.After several rounds of screening and cloning,the hybridomas which secreted the antibodies against the extracellular domain or the intracellular domain of human FXYD6 were established.The antibody specificity and subtype were identified with indirect ELISA,western blot and immunohistochemistry.The monoclonal antibodies against the extracellular domain which recognized the native conformation were screened with flow cytometry.The antibody against extracellular region was prepared with the ascites revulsion method and purified.The affinity constants were measured with indirect ELISA.The function of extracellular monoclonal antibody was detected by HepG2 cell line with high expression of FXYD6.Results The hybridoma cell library which secreted the monoclonal antibody against extracellular domain or the intracellular domain of human FXYD6 was successfully obtained,and extracellular region monoclonal antibodies with the functional blocking were prepared.Conclusion The prepared anti-human FXYD6 extracellular monoclonal antibodies could inhibit HepG2 cell proliferation.

FXYD6: a novel therapeutic target toward hepatocellular carcinoma

FXYD6, FXYD domain containing ion transport regulator 6, has been reported to affect the activity of Na(+)/K(+)-ATPase and be associated with mental diseases. Here, we demonstrate that FXYD6 is up-regulated in hepatocellular carcinoma (HCC) and enhances the migration and proliferation of HCC cells. Up-regulation of FXYD6 not only positively correlates with the increase of Na(+)/K(+)-ATPase but also coordinates with the activation of its downstream Src-ERK signaling pathway. More importantly, blocking FXYD6 by its functional antibody significantly inhibits the growth potential of the xenografted HCC tumors in mice, indicating that FXYD6 represents a potential therapeutic target toward HCC. Altogether, our results establish a critical role of FXYD6 in HCC progression and suggest that the therapy targeting FXYD6 can benefit the clinical treatment toward HCC patients.

The establishment and meaning of the three-dimensional finite element model of pelvic floor levator ani muscle in an old healthy woman / 生物医学工程学杂志

This paper is to establish a three-dimensional finite element model (3D-FEM) of pelvic floor levator ani muscles in an old healthy women. We acquired the image data of the pelvic bones and pelvic floor muscles from CT and MRI scanning in a non-pregnant old healthy female volunteers. The 3-D reconstruction and mesh optimization of the whole pelvic bones and muscles with application of image processing software Mimics12.0 and Geomagic9.0 were obtained. Then we built the 3D-FEM of the musculoskeletal system of the pelvic bones and levator ani muscles with Ansys11.0 software. We obtained an accurate 3D-FEM of pelvic bones and levator ani muscles in the older healthy woman. The results showed that it was reliable to build 3D-FEM with CT and MRI scanning data and this model could vividly reflect the huge space anatomy of the real pelvic floor levator ani muscles. It avoids the defects to gain the model from the body of anatomical specimens in the past. The image data of model are closer to vivisection, and the model is more conducive to the latter finite element analysis.

Comparison between Da Vinci surgical system-assisted and open surgery in pancreatoduodenectomy / 中华消化外科杂志

objective To summarize the clinical experience of pancreatoduodenectomy using Da Vinci surgical system,and to investigate the methods to improve its efficacy.Methods Sixteen patients who received pancreatoduodenectomy from January to December 2009 at the General Hospital of Second Artillery of PLA were divided into robotic group(n=8)and open group(n=8).Data on the surgical procedure,perioperative management and postoperative recovery between the 2 groups were retrospectively analysed using t test and chi-square test.Result The radical resection rates of robotic group and open group were 7/8 and 8/8,respectively,with no significant difference between the 2 groups(χ~2=1.067,P＞0.05).The operation time of robotic group was (718±186)minutes,which was significantly longer than(420±127)minutes of open group(t=3.714,P＜0.05＝.The blood loss of robotic group was(153±43)ml,which was significantly less than(210±53)ml of open group(t=2.318,P＜0.05＝.The postoperative ambulation time and length of hospital stay of robotic group were(28±7)hours and(16±4)days,which were significantly shorter than(96±18)hours and(24±7)days of open group(t=9.939,2.714,P＜0.05＝.The incidences of postoperative complications of robotic group and open group were 2/8 and 6/8,respectively,with significant difference between the 2 groups(χ~2=6.349,P＜0.05＝.The incidences of anastomotic leakage of robotic group and open group were 2/8 and 3/8,respectively,with no significant difference between the 2 groups(χ~2=0.291,P＞0.05).Conclusion Pancreatoduodenectomy performed by Da Vinci surgical system is feasible and safe,and with the advantages of less trauma and rapid recovery of patients.