MHC/peptide tetramer technology has been widely used to study antigen-specific T cells, especially for identifying virus-specific CD8^＋ T cells in humans. The tetramer molecule is composed of HLA heavy chain, β2-mic...MHC/peptide tetramer technology has been widely used to study antigen-specific T cells, especially for identifying virus-specific CD8^＋ T cells in humans. The tetramer molecule is composed of HLA heavy chain, β2-microglobulin （β2m）, an antigenic peptide, and fluorescent-labeled streptavidin. To further investigate the HLA-A＊1101-restricted CD8^＋ T cell responses against human cytomegalovirus （HCMV）, we established an approach to prepare HLA-A＊1101 tetramer complexed with a peptide from HCMV. The cDNA encoding HLA-A＊1101 heavy chain was cloned and the prokaryotic expression vector for the ectodomain of HLA-A＊1101 fused with a BirA substrate peptide （HLA-A＊1101-BSP） at its carboxyl terminus was constructed. The fusion protein was highly expressed as inclusion bodies under optimized conditions in Escherichla coli. Moreover, HLA-A＊1101-BSP protein was refolded in the presence of β2m and an HCMV peptide pp6516.24 （GPISGHVLK, GPI）. Soluble HLA-A＊1101-GPI monomer was biotinylated and purified to a purity of 95%, which was subsequently combined with streptavidin to form tetramers at a yield of 〉 80%. The HLA-A＊1101-GPI tetramers could bind to virus-specific CD8^＋ T cells, suggesting soluble HLA-A＊1101-GPI tetramers were biologically functional. This study provides the basis for further evaluation of HLA-A＊1101-restricted CD8^＋ T cell responses against HCMV infection.展开更多
文摘目的探讨人类白细胞抗原(human leukocyte antigen,HLA)基因多态性与乙型肝炎病毒(HBV)感染的相关性。方法收集云南省昆明市延安医院健康体检者静脉血样本501例,采用酶联免疫吸附试验(ELISA)检测HBV二对半,根据HBV二对半检测结果分为HBV携带组和既往感染组以及健康对照组3组,用序列特异性引物聚合酶链反应(polymerase chain reaction with sequence specific primers,PCR-SSP)基因分型技术检测HLA-A抗原的基因型,将HBV携带组和健康对照组以及HBV既往感染组和健康对照组的HLA-A基因多态性的分布频率进行比较。采用SPSS17.0软件进行数据统计分析。结果健康对照组HLA-A2阳性数占比47.49%,等位基因频率数占比31.29%;健康对照组基因分布频率总体与中华骨髓库发布的中国常见及确认的HLA-A等位基因表一致。HBV携带组HLA-A2阳性数占比63.04%,等位基因频率数占比42.23%,携带者的HLA-A2阳性率和等位基因频率差异有统计学意义(P<0.05);HBV既往感染组HLA-A2阳性数占比56.14%,等位基因频率数占比35.97%,既往感染组的HLA-A2阳性率和等位基因频率差异无统计学意义(P>0.05)。结论HLA-A2基因可能是慢性乙型肝炎HBV携带者的易感基因。
基金supported by grants from the National Natural Science Foundation of China(No.30230350,No.30572199 and No.30371651).
文摘MHC/peptide tetramer technology has been widely used to study antigen-specific T cells, especially for identifying virus-specific CD8^＋ T cells in humans. The tetramer molecule is composed of HLA heavy chain, β2-microglobulin （β2m）, an antigenic peptide, and fluorescent-labeled streptavidin. To further investigate the HLA-A＊1101-restricted CD8^＋ T cell responses against human cytomegalovirus （HCMV）, we established an approach to prepare HLA-A＊1101 tetramer complexed with a peptide from HCMV. The cDNA encoding HLA-A＊1101 heavy chain was cloned and the prokaryotic expression vector for the ectodomain of HLA-A＊1101 fused with a BirA substrate peptide （HLA-A＊1101-BSP） at its carboxyl terminus was constructed. The fusion protein was highly expressed as inclusion bodies under optimized conditions in Escherichla coli. Moreover, HLA-A＊1101-BSP protein was refolded in the presence of β2m and an HCMV peptide pp6516.24 （GPISGHVLK, GPI）. Soluble HLA-A＊1101-GPI monomer was biotinylated and purified to a purity of 95%, which was subsequently combined with streptavidin to form tetramers at a yield of 〉 80%. The HLA-A＊1101-GPI tetramers could bind to virus-specific CD8^＋ T cells, suggesting soluble HLA-A＊1101-GPI tetramers were biologically functional. This study provides the basis for further evaluation of HLA-A＊1101-restricted CD8^＋ T cell responses against HCMV infection.
文摘射频电路优化设计是保证射频通信系统高可靠、低功耗、远距离数据传输的重要手段。针对商用CC1101射频电路传输距离短和丢包率高的问题,通过高频电磁仿真软件ADS(Advanced Design System)对CC1101射频电路中阻抗变换器、滤波器和射频全链路进行仿真优化,根据仿真结果调整元器件,并测试了改版CC1101射频电路的传输距离和数据包接收率。结果表明,优化后射频电路阻抗(115+j42Ω)更接近目标差分阻抗(116+j41Ω),回波损耗提高11 d B,插入损耗减少0.6 d B,稳定传输距离提升30 m,在传输距离为60 m时数据接收率提高33.6%。
