Computational and statistical study on the molecular interaction between antigen and antibody

Monoclonal antibodies are one of the most successful bio-molecules utilized in the clinical scene of today. It is important to clarify general characteristics of the interaction between antigen and antibody and to draw a guide for enhancing their binding affinity in rational design of antibody drugs. In this study, we carried out molecular dynamics simulations for 20 kinds of antigen–antibody complexes. From the statistical analysis of the calculation results, the following findings were deduced. At complementarity determining regions (CDRs) of the antibodies, the rates for the presence of serine (Ser) and tyrosine (Tyr) are high. The amino residues involved in direct hydrogen bonds between antigens and antibodies were examined by counting the numbers of the hydrogen bonds from the respective residues. The contribution of Tyr to the direct hydrogen bonding was the highest and that of Ser was the fourth. Furthermore, the short-distance hydrogen bonds, which is assumed to be so-called “low-barrier hydrogen bond”, were observed at CDRs in three complexes. Interestingly, Ser is involved in the short-distance hydrogen bonding in two cases out of the three. This result suggests that these two unchanged polar amino acid residues play an important role for recognition of antigen. In almost all of the complexes (18/20), the contribution of the electrostatic energy (ΔE_ele) to the binding free energy was calculated to be larger than that of the van der Waals energy (ΔE_vdw). This dominance of the electrostatic energy is in contrast to the case that low molecular-weight compounds are bound to their targets. The findings of this study will be helpful to design an antibody with a high specificity and a high affinity to the antigen.     

骨化三醇对实验性自身免疫性脑脊髓炎的治疗作用及相关机制

目的探讨骨化三醇(Calcitriol)对实验性自身免疫性脑脊髓炎(Experimental autoimmune encephalomyelitis,EAE)的治疗作用及相关机制。方法用含200μg髓鞘少突胶质细胞糖蛋白35-55肽段(Myelin oligodendrocyte glycoprotein 33-35,MOG33-35)、250μg结核菌素的50μl弗氏不完全佐剂(IFA)皮内免疫C57BL/6小鼠,并分别于免疫当天和第2天注射百日咳毒素,建立EAE实验性动物模型(EAE组);骨化三醇组从免疫当天起隔日腹腔注射骨化三醇100 ng进行治疗,观察两组小鼠临床评分的差异;于EAE发病高峰期处死小鼠,取脊髓及淋巴结,通过HE及LFB染色观察脊髓中炎细胞浸润及髓鞘脱失;采用流式细胞术检测两组淋巴细胞CD4+T细胞亚型的分布。结果与EAE组比较,骨化三醇组发病延缓且发病较轻,临床评分差异有统计学意义(P<0.05或P<0.01或P<0.001);骨化三醇组较EAE组小鼠脊髓白质炎性细胞浸润明显减少,脱髓鞘斑块明显减轻;骨化三醇组与EAE组相比,Th17细胞亚群明显受到抑制(P<0.05),而Th2和Treg细胞水平明显升高(P均<0.05)。结论骨化三醇可以延缓EAE发病,减轻临床症状及病理改变,并能够通过调节CD4+T细胞亚群平衡,即抑制Th17细胞,上调Th2和Treg细胞水平发挥对EAE的预防和治疗作用。     

甲型肝炎病毒(L-A-1株)基因型分析

目的 分析甲肝病毒基因型,为确定我国甲肝的分子流行病学及疫苗的安全性和免疫原性奠定基础。方法 采用抗原捕获聚合酶链反应（AC/PCR）,依据国际上甲肝病毒分型标准,扩增VP1/2A结合处的168个核苦酸（nt2909～3264）。结果 经生物信息学软件分析,得出L-A-1株病毒属于甲肝病毒基因IB亚型。结论 在我国有IA和IB两个亚型甲肝病毒流行。     

血清结合甘胆酸放射免疫分析药盒研制(阻断法)

人血清中结合甘胆酸含量测定,采用阻断法放射免疫分析药盒,达到直接测定血样中结合甘胆酸的含量。本药盒以~(125)I-甘胆酸组胺为标记抗原,放化纯>90%。用去激素正常人血清配制系列标准,标准浓度分别为0.25.100.250.1000.4000μg/dl。兔抗血清,16~#兔抗血清亲和常数K=2.6×10~8l/mol。以0.5%ANS(8-苯胺-1-萘磺酸)磷酸盐缓冲溶液为阻断剂。PEG(聚乙二醇)为分离沉淀剂。本药盒分析灵敏度10μg/dl。批内批间精密度分别为4.7%和12.5%。平均回收率109%。     

微波在免疫组织化学中的应用

本文综述微波技术在免疫组织化学中的应用两头及其进展，着重介绍了微波在组织固定、抗原恢复和免疫染色方面的应用，并对微波免疫组织化学的应用前景进行了展望 。     

基于人工免疫机制的马达调速控制研究

运用生物信息处理机制和恒压网络技术进行马达速度控制。利用免疫系统对干扰快速响应并且能使系统迅速稳定的特性，构造了结构简单、鲁棒性强的控制器。仿真结果表明，该方法简单有效。     

Quantitative analysis of the number of antigens immobilized on a glass surface by AFM

To develop force measurements using an atomic force microscope (AFM) in a quantitative manner, it is necessary to estimate the number density of target molecules on a sample surface, and for this, the sensitivity of detection should be known. In this study, the AFM was used as a mechanical detector and an antigen and its antibody were used as a model to evaluate the sensitivity of detection. Antigens were immobilized on a glass surface and number density was estimated by monitoring optical absorbance due to product formation by the reaction of crosslinkers. The concentration of antigen was controlled by mixing control peptides. A microbead was used as a probe and antibodies were immobilized on the bead. AFM force measurements were then made for a range of number densities in the order of 10–10⁶ antigen molecules per square micrometer of surface and were compared to evaluate the sensitivity of detection. Our result establishes the reliability of estimating a number of molecules like receptors on the cell surface, and indicates that the AFM is useful as a mechanical detector with high sensitivity.     

Proteomics integrated with Escherichia coli vector-based vaccines and antigen microarrays reveals the immunogenicity of a surface sialidase-like protein of Propionibacterium acnes

Proteomics is a powerful tool for the identification of proteins, which provides a basis for rational vaccine design. However, it is still a highly technical and time‐consuming task to examine a protein's immunogenicity utilizing traditional approaches. Here, we present a platform for effectively evaluating protein immunogenicity and antibody detection. A tetanus toxin C fragment (Tet‐c) was used as a representative antigen to establish this platform. A cell wall‐anchoring sialidase‐like protein (SLP) of Propionibacterium acnes was utilized to assess the efficacy of this platform. We constructed an Escherichia coli vector‐based vaccine by overexpressing Tet‐c or SLP in E. coli and utilized an intact particle of E. coli itself as a vaccine (E. coli Tet‐c or SLP vector). After ultraviolet (UV) irradiation, the E. coli vector‐based vaccines were administered intranasally into imprinting control region mice without adding exogenous adjuvants. For antibody detection, we fabricated antigen microarrays by printing with purified recombinant proteins including Tet‐c and SLP. Our results demonstrated that detectable antibodies were elicited in mice 6 weeks after intranasal administration of UV‐irradiated E. coli vector‐based vaccines. The antibody production of Tet‐c and SLP was significantly elevated after boosting. Notably, the platform with main benefits of using E. coli itself as a vaccine carrier provides a critical template for applied proteomics aimed at screening novel vaccine targets. In addition, the novel immunogenic SLP potentially serves as an antigen candidate for the development of vaccines targeting P. acnes‐associated diseases.     

A shear horizontal surface acoustic wave sensor for the detection of antigen–antibody reactions for medical diagnosis

In this paper we describe the development of a shear horizontal surface acoustic wave immunosensor for medical diagnostics. There exists a strong interest in the rapid detection of antigen–antibody reactions at small concentrations in the g/ml region in plasma, serum, or whole blood. Sensors whose operating principle is based on shear horizontal acoustic surface waves are well suited for this. We have used a spin-on glass film for the guidance of the surface wave as well as for the protection of the aluminum structures of the surface wave transducers from aggressive analyte liquids. This film has proven to considerably enhance the sensitivity of the device, and to simultaneously provide a durable protection of the transducers. Furthermore, polymers based on polyvinylamines have been used for the first time for immobilization of the capture protein. This technique effectively prevents the undesired binding of foreign substances like cells, non-specific antibodies, or other proteins at the sensor surface.     

一种基于AIS和Bayes网络的垃圾邮件过滤算法

将人工免疫系统和贝叶斯网络相结合应用于垃圾邮件的过滤，设计了一个基于AIS和Bayes网络的垃圾邮件过滤算法，分析并解决了该算法实现过程中的关键问题，给出了亲和力的计算方法和抗原/抗体的结构定义。在PU1bare 语料的基础上与Carreras提出的AdaBoost方法进行对比实验，最后给出了实验结果。