Prediction of a common neutralizing epitope of H5N1 avian influenza virus by in silico molecular docking

The H5N1 avian influenza virus （AIV） has widely spread in Asia, Europe and Africa, making a large amount of economic loss. Recently, our research group has screened a common neutralizing mono-clonal antibody named 8H5, which can neutralize almost all H5 subtype AIV ever isolated so far. Obviously, this monoclonal antibody would benefit for research and development of the universal AIV vac-cine and design of the drug against H5N1 AIV in high mutation rate. In this study, the homology modeling was applied to generate the 3D structure of 8H5 Fab fragment, and ＂canonical structure＂ method was used to define the specified loop conformation of CDR regions. The model was subjected to energy minimization in cvff force field with Discovery module in Insight II program. The resulting model has correct stereochemistry as gauged from the Ramachandran plot calculation and good 3D-structure compatibility as assessed by interaction energy analysis, solvent accessible surface （SAS） analysis, and Profiles-3D approach. Furthermore, the 8H5 Fab model was subjected to docking with three H5 subtype hemagglutinin （HA） structures deposited in PDB （ID No： ljsm, 2ibx and 2fk0） respectively. The result indicates that the three docked complexes share a common binding interface, but differ in binding angle related with HA structure similarity between viral subtypes. In the light of the three HA inter-faces with structural homology analysis, the common neutralizing epitope on HA recognized by 8H5 consists of 9 incontinuous amino acid residues： Asp^58, Asn^72, Glu^112, Lys^113, lie^114, Pro^118, Ser^120, Tyr^137, Tyr^252 （numbered as for ljsm sequence）. The primary purpose of the present work is to provide some insight into structure and binding details of a common neutralizing epitope of H5N1 AIV, thereby aiding in the structure-based design of universal AIV vaccines and anti-virus therapeutic drugs.     

双抗体夹心ELISA检测禽流感病毒方法的初步建立

用饱和硫酸铵初步纯化的兔抗AIV-H9高免血清中的IgG作为包被抗体,利用抗AIV-NP-7B4单抗作为ELISA的第二抗体,建立了检测禽流感病毒(AIV)抗原的双抗体夹心ELISA方法. 经方阵滴定试验测定反应的最佳工作条件为:兔抗AIV-H9高免血清IgG包被稀释度为1: 8 000(浓度为3.531 ug/mL),抗AIV-NP-7B4单抗腹水最佳使用稀释度为1: 800,酶标二抗的工作浓度为1: 4 000. 与其他禽易感病毒(NDV、IBV、EDS-76V)等均没有交叉反应. 结果表明,本方法具有很高的特异性.     

甲型H1N1流感的微分方程模型

以经典的传染病模型(SIR模型)为基础,结合甲型H1N1流感的临床表现、传染途径及传播规律,建立了甲型H1N1流感在预防和控制阶段的传播模型.结合实际数据,对甲型H1N1流感传播趋势做出预测,预测结果与实际情况基本吻合,说明该微分方程模型对甲型H1N1流感传播趋势的预测是有意义的.     

流感病毒疫苗研究现状、发展趋势和展望

 流感大流行严重威胁人类的生命健康和社会经济的发展。及时提供充足、有效的流感疫苗是目前各国应对流感大流行的首选方法。然而,目前流感疫苗还存在许多问题,如生产周期长、保护范围有限（不具备广谱性）、易产生过敏反应等。为此,各国政府和科研团体都在进行着不懈的努力以应对流感的大流行。本文介绍了目前国内外使用的流感疫苗,比较了流感灭活疫苗和减毒活疫苗的优缺点;针对当前流感病毒疫苗研制中亟待解决的问题,即疫苗的保护时效及合适的培养基问题,探讨了解决的思路以及取得的进展;结合中国在流感方面的主要研究进展,探讨了中国流感病毒疫苗相关基础研究中需要解决的关键科学问题,并对未来流感的防控进行了展望。     

The novel H1N1 Influenza A global airline transmission and early warning without travel containments

A novel influenza A (H1N1) has been spreading worldwide. Early studies implied that international air travels might be key cause of a severe potential pandemic without appropriate containments. In this study, early outbreaks in Mexico and some cities of United States were used to estimate the preliminary epidemic parameters by applying adjusted SEIR epidemiological model, indicating transmissibility infectivity of the virus. According to the findings, a new spatial allocation model totally based on the real-time airline data was established to assess the potential spreading of H1N1 from Mexico to the world. Our estimates find the basic reproductive number R0 of H1N1 is around 3.4, and the effective reproductive number fall sharply by effective containment strategies. The finding also implies Spain, Canada, France, Panama, Peru are the most possible country to be involved in severe endemic H1N1 spreading.     

Subtyping of type A influenza by sequencing the variable regions of HA gene specifically amplified with RT-PCR

The outbreak of a novel influenza A(H1N1) virus across the globe poses a threat to human health.It is of paramount importance to develop a rapid,reliable and inexpensive diagnostic procedure.Based on the bioinformatic information from public database,primers specific for influenza A virus surface protein haemagglutinin(HA) of several subtypes(including H1,H2,H3,H5,H7 and H9) were designed.Primer-specific PCR products were subjected to sequencing for accurately distinguishing H1 and H3 subtypes from others.T...     

Increased substitution rate in H5N1 avian influenza viruses during mass vaccination of poultry

As a means of heated debate,mass vaccination of poultry has been used in some countries to control H5N1 highly pathogenic avian influenza(HPAI),which remains of global economic and public health significance.Theoretically,mass vaccination can act as an evolutionary selective force facilitating the emergence of vaccine-resistant viruses,similar to that widespread use of antibiotics facilitates the emergence of antibiotic-resistant bacteria.To support the hypothesis,the substitution rates in the two subunits,HA1 and HA2,of the viral hemagglutinin gene,were calculated using a Bayesian Markov Chain Monte Carlo(MCMC) approach.It was found that the rate in the HA1 subunit,but not in the HA2 subunit,increased significantly during periods of mass vaccination(2005 2010 in China and 2003 2009 in Indonesia),in contrast to the periods when no mass vaccination programs took place(1996 2004 in China and 2004 2008 in Thailand).Because substitutions in the HA1 subunit rather than in the HA2 subunit can lead to vaccine-resistant viruses,the results support that mass vaccination programs facilitate the emergence of vaccine-resistant viruses,which,in turn,will render mass vaccination programs less effective.Therefore,caution must be taken when adopting mass vaccination as a long-term strategy to control HPAI.     

禽流感及人感染高致病性禽流感的危害和防治措施

阐述了禽流感病毒的特点及其流行病学特征,着重介绍了人感染高致病性禽流感的致病机制、治疗措施和预防的方法。     

抗禽流感iRNA提取及其部分免疫活性的研究

为了比较不同方法抽提抗禽流感iRNA的含量、纯度,以及了解iRNA对小鼠的免疫活性,本研究就抗禽流感iRNA提取及其部分免疫活性进行了研究。结果表明:酚-氯仿抽提与Trizol reagent试剂盒抽提的效果差异不显著,所得到的iRNA含量和纯度较高,而冷热酚法抽提的效果则明显不及酚-氯仿法与Trizol reagent试剂盒;小白鼠腹腔注射提取的iRNA制剂,小白鼠生长良好,10 d内未见小白鼠有死亡,由此说明iRNA对小白鼠是安全的;禽流感HI试验及ELISA试剂盒检测iRNA免疫小白鼠血清抗体,结果为阴性,由此说明抽提的iRNA不能诱导机体产生体液免疫。