Molecular Design and Immunogenicity of a Multiple-epitope FMDV Antigen and DNA Vaccination

This article reports the design and construction of a multiple-epitope foot and mouth disease virus （FMDV） antigen, designated as OAAT. This recombinant antigen consists of the structural protein VP1 genes from serotypes A and O FMDV, five major VP1 immunodominant epitopes from two genotypes of Asial serotype, and three Th2 epitopes originating from the nonstructural protein, three ABC gene and structural protein VP4 gene. Expressions of target gene from these plasmids in HeLa cells were verified by Western-blot. BALB/c mice were immunized intramuscularly with the DNA vaccines thrice every two weeks. We found that pA could induce simultaneously specific antibodies against serotypes A, Asial, and O FMDV. Compared to those of the controls, the spots of FMDV-specific IFN-7 and cytotoxic activity from mice immunized with pA were significantly increased, pA provided full protection in 2/4 guinea pigs from challenge with FMDV O/NY00 and Asial/YNBS/58, respectively. The results show that although pA did not give full protection in 100% immunized guinea pigs from challenge with type O and Asial FMDV, respectively, OAAT may be potential immunogen against FMDV and pA may be potential DNA vaccines against FMDV.     

病毒传播的动态分析

结合最新病毒传播的研究工作,建立了一系列微观病毒传播系统,并对动态系统作了简单的分析,是对宏观疾病传播的内在规律的描述和研究,有利于疾病发展趋势的预测和最优化控制策略的研究.     

Computer simulation of a cellular automata model for the immune response in a retrovirus system

Immune response in a retrovirus system is modeled by a network of three binary cell elements to take into account some of the main functional features of T4 cells, T8 cells, and viruses. Two different intercell interactions are introduced, one of which leads to three fixed points while the other yields bistable fixed points oscillating between a healthy state and a sick state in a mean field treatment. Evolution of these cells is studied for quenched and annealed random interactions on a simple cubic lattice with a nearest neighbor interaction using inhomogenous cellular automata. Populations of T4 cells and viral cells oscillate together with damping (with constant amplitude) for annealed (quenched) interaction on increasing the value of mixing probabilityB from zero to a characteristic valueB _ca (B _cq). For higherB, the average number of T4 cells increases while that of the viral infected cells decreases monotonically on increasingB, suggesting a phase transition atB _ca (B _cq).     

An Ultrasensitive Virus ELISA Based on a magnetic Mesoporous Silica Nanoprobe

Detection of infectious viruses relies on quantitative polymerase chain reaction (qPCR). However, qPCR requires costly equipment, a clean operating environment and experienced technicians, limiting its wide applicability. On the other hand, enzyme-linked immunosorbent assay (ELISA) is widely used in biological laboratories due to its relatively high sensitivity and ease of operation. However, ELISA-based detection of the virus is hampered because it is lower sensitive than qPCR. Herein, a nanoprobe ELISA (NP-ELISA) based on a mesoporous silica nanoprobe, which is constructed by first being loaded with peroxidase and further coated with positively charged polymer polyethyleneimine, and finally functionalized with antivirus antibodies, is designed. Results show that each NP probe is encapsulating 170 peroxidase molecules and presents 200 antibody molecules on the surface. The limit of detection (LOD) of NP-ELISA (LOD = 1450 PFU mL⁻¹) for the detection of real virus samples is tenfold sensitive than that of standard ELISA (LOD = 14, 414 PFU mL⁻¹) and the assay time for NP-ELISA is reduced by 1 h as compared with standard one. Therefore, the NP-ELISA provides a rapid and sensitive immunoassay platform that can readily be implemented for biological laboratory research as well as for on-site clinical diagnostics.     

Beyond labels: A review of the application of quantum dots as integrated components of assays, bioprobes, and biosensors utilizing optical transduction

A comprehensive review of the development of assays, bioprobes, and biosensors using quantum dots (QDs) as integrated components is presented. In contrast to a QD that is selectively introduced as a label, an integrated QD is one that is present in a system throughout a bioanalysis, and simultaneously has a role in transduction and as a scaffold for biorecognition. Through a diverse array of coatings and bioconjugation strategies, it is possible to use QDs as a scaffold for biorecognition events. The modulation of QD luminescence provides the opportunity for the transduction of these events via fluorescence resonance energy transfer (FRET), bioluminescence resonance energy transfer (BRET), charge transfer quenching, and electrochemiluminescence (ECL). An overview of the basic concepts and principles underlying the use of QDs with each of these transduction methods is provided, along with many examples of their application in biological sensing. The latter include: the detection of small molecules using enzyme-linked methods, or using aptamers as affinity probes; the detection of proteins via immunoassays or aptamers; nucleic acid hybridization assays; and assays for protease or nuclease activity. Strategies for multiplexed detection are highlighted among these examples. Although the majority of developments to date have been in vitro, QD-based methods for ex vivo biological sensing are emerging. Some special attention is given to the development of solid-phase assays, which offer certain advantages over their solution-phase counterparts.     

纳米探针芯片技术用于微量乙肝病毒DNA的检测

利用两组探针修饰的微粒:(1)表面标记有可与待测乙肝病毒(HBV) DNA另一端结合的纳米金探针1(信号探针)以及可与信号探针部分结合的纳米金探针2(检测探针);(2)表面标记有可与待测HBV DNA一端结合的磁珠探针(捕捉探针1).检测靶HBV DNA时,磁珠探针与信号探针在液相中可分别与HBV DNA靶序列一端结合最终形成三明治样结构.再以磁场将三明治样复合物从反应液中分离,以DTT溶液将信号探针从纳米金颗粒上洗脱.洗脱后的信号探针数量反映靶基因的多寡,信号探针一段与预先点样的基因芯片上的捕捉探针2结合,检测探针与信号探针另一段相结合,最后用银染液将检测探针显色从而得到靶目标DNA相对定量信息.结果表明,本检测方法的检测灵敏度达到10-15 mol/L水平.检测时间少于1.5 h,检测结果与HBV DNA水平呈现较好的线性关系且无假阳性结果;本方法有望用于乙肝病人血清中HBV DNA的快速筛测及其它微生物基因的检测.     

Dynamical behaviors of a discrete HIV‐1 virus model with bilinear infective rate

We establish a discrete virus dynamic model by discretizing a continuous HIV‐1 virus model with bilinear infective rate using ‘hybrid’ Euler method. We discuss not only the existence and global stability of the uninfected equilibrium but also the existence and local stability of the infected equilibrium. We prove that there exists a crucial value similar to that of the continuous HIV‐1 virus dynamics, which is called the basic reproductive ratio of the virus. If the basic reproductive ratio of the virus is less than one, the uninfected equilibrium is globally asymptotically stable. If the basic reproductive ratio of the virus is larger than one, the infected equilibrium exists and is locally stable. Moreover, we consider the permanence for such a system by constructing a Lyapunov function v_n. Copyright © 2013 John Wiley & Sons, Ltd.     

有Logistic增长的媒介传播模型分析

建立了贮存宿主鸟类与传染宿主蚊子都具有Logistic增长的西尼罗河病毒传播模型,获得了基本再生数R_0.当R_0<1时,通过构造Lyapunov函数,证明了无病平衡点的全局渐近稳定性.当R_0>1,且满足不同条件时,得到了正平衡点的存在性,数值模拟验证了理论结果的正确性.