Molecular basis of the structure and function of H1 hemagglutinin of influenza virus

Influenza virus hemagglutinin (HA) contains antigenic sites recognized by the host immune system, cleavage sites cleaved by host proteases, receptor binding sites attaching to sialyl receptors on the target cell, and fusion peptides mediating membrane fusion. Change in an amino acid(s) in these sites may affect the potential of virus infection and spread within and between hosts. Influenza viruses with H1 HA infect birds, pigs and humans and have caused two of the four pandemics in the past 100 years: 1918 pandemic that killed 21-50 million people and 2009 pandemic that caused more than 18,000 deaths. Understanding the relationship between antigenic structure and immune specificity, the receptor binding specificity in virus transmission, how the cleavage site controls pathogenicity, and how the fusion peptide causes membrane fusion for the entry of influenza virus into the host cell should provide information to find more effective ways to prevent and control influenza.     

Voltammetric Detection of a Specific DNA Sequence of Avian Influenza Virus H5N1 Using HS‐ssDNA Probe Deposited onto Gold Electrode

The working principle of a genosensor is based on the mechanism of ion‐channel mimetic sensors. The analytical signals generated upon hybridization processes were recorded by a redox active marker [Fe(CN)₆]^3?/4? present in the sample solution using voltammetric techniques. The developed genosensor was suitable for determination of 20‐mer complementary oligonucleotide sequence, and also of the PCR products containing the complementary 20‐mer sequence in various positions, with detection limits in the 10 pM range. The noncomplementary 20‐mer oligonucleotide sequence as well as the PCR product without complementary region generated very weak response. The good discrimination of the position of the complementary part in the PCR products was observed.     

p16蛋白对B型流感病毒诱导HeLa细胞凋亡的影响

以流感病毒 B/沪防 93- 1株感染 He L a细胞 ,通过 Hoechst332 5 8荧光染色、琼脂糖凝胶电泳分析检测细胞凋亡 ,并用免疫组化技术测定 p16蛋白的表达 ,探讨 p16蛋白表达对 He L a细胞凋亡的影响 .结果表明 ,B型流感病毒感染 He L a细胞可诱导其凋亡 ,感染 2 4h后 ,细胞凋亡数达 84.5 % ;He L a细胞凋亡伴随 p16蛋白的表达 ,2 4h达高峰 ,阳性率为 49.2 3± 1.70 .研究结果提示 ,B型流感病毒感染诱导 He L a细胞凋亡过程与 p16基因激活相关 ,p16蛋白可能是介导流感病毒诱导细胞凋亡的另一重要途径 .     

Ultrastructural Damages to H1N1 Influenza Virus Caused by Vapor Essential Oils

Influenza viruses are transmitted from human to human via airborne droplets and can be transferred through contaminated environmental surfaces. Some works have demonstrated the efficacy of essential oils (EOs) as antimicrobial and antiviral agents, but most of them examined the liquid phases, which are generally toxic for oral applications. In our study, we describe the antiviral activity of Citrus bergamia, Melaleuca alternifolia, Illicium verum and Eucalyptus globulus vapor EOs against influenza virus type A. In the vapor phase, C. bergamia and M. alternifolia strongly reduced viral cytopathic effect without exerting any cytotoxicity. The E. globulus vapor EO reduced viral infection by 78% with no cytotoxicity, while I. verum was not effective. Furthermore, we characterized the EOs and their vapor phase by the head-space gas chromatography–mass spectrometry technique, observing that the major component found in each liquid EO is the same one of the corresponding vapor phases, with the exception of M. alternifolia. To deepen the mechanism of action, the morphological integrity of virus particles was checked by negative staining transmission electron microscopy, showing that they interfere with the lipid bilayer of the viral envelope, leading to the decomposition of membranes. We speculated that the most abundant components of the vapor EOs might directly interfere with influenza virus envelope structures or mask viral structures important for early steps of viral infection.     

黑色素对流感病毒诱导细胞凋亡的抑制效应

用荧光染色技术及流式细胞仪分析方法研究了 Ａ１／京防８６１ 和 Ｂ／沪防９３１ 两株流感病毒感染与细胞凋亡的关系,探讨利用嗜麦芽假单胞菌黑色素抑制流感病毒诱导 Ｍ Ｄ Ｃ Ｋ 细胞凋亡的可能性 结果显示：黑色素在 １００ ｍ ｇ· Ｌ－ １ 浓度范围内,对 Ｍ Ｄ Ｃ Ｋ 细胞无细胞毒性; Ａ１／京防 ８６１ 和 Ｂ／沪防 ９３１ 两株流感病毒均可诱导 Ｍ Ｄ Ｃ Ｋ细胞凋亡,但二者存在毒力差异（ｐ＜ ０．０５）病毒感染１２ ｈ 后,荧光染色可观察到典型的凋亡核形态,流式细胞仪则可检测到病毒诱导 Ｍ Ｄ Ｃ Ｋ 细胞产生的凋亡峰,且细胞凋亡率分别为３７．０２％ 和 ２７２９％ ;２０ ｍ ｇ· Ｌ－ １ 的黑色素可有效抑制两株流感病毒诱导细胞凋亡,使细胞凋亡指数从２５％ ～３５％ 降至３％ 以下 结果表明,黑色素可以抑制 Ａ 和 Ｂ型流感病毒诱导细胞凋亡     

焦测序法检测禽流感病毒

以焦测序技术为检测平台,在研究禽流感病毒基因特性的基础上,建立一种检测禽流感病毒及确定其是否为高致病性禽流感病毒的序列测定法。首先,选择一段保守的M基因序列及一段包含裂解位点的HA基因序列为研究对象,采用聚合酶链反应(polymerase chain reaction,PCR)扩增技术初步判断其是否为禽流感病毒及病毒亚型;然后采用焦测序法检测目的片段序列;最后,对焦测序法检测序列进行分析,从基因序列上判断其是否为禽流感病毒,并进一步判断病毒的亚型以及是否为高致病性禽流感病毒。研究结果表明,当焦测序反应中三磷酸酰苷双磷酸酶(Apyrase)的浓度为1.6U/mL时,能有效抑制错误信号的产生;当Klenow的浓度为90U/mL时,可读序列长度为33个碱基。采用优化的焦测序反应体系测定了4个样本,其中1个样本被判断为H5N1亚型禽流感病毒,具有潜在的高致病性;另外3个样本为H9N2型禽流感病毒,具有低致病性。本方法具有准确、快速和实时检测等优点。     

In Silico Drug Repurposing of FDA-Approved Drugs Highlighting Promacta as a Potential Inhibitor of H7N9 Influenza Virus

Influenza virus infections continue to be a significant and recurrent public health problem. Although vaccine efficacy varies, regular immunisation is the most effective method for suppressing the influenza virus. Antiviral drugs are available for influenza, although two of the four FDA-approved antiviral treatments have resulted in significant drug resistance. Therefore, new treatments are being sought to reduce the burden of flu-related illness. The time-consuming development of treatments for new and re-emerging diseases such as influenza and the high failure rate are increasing concerns. In this context, we used an in silico-based drug repurposing method to repurpose FDA-approved drugs as potential therapies against the H7N9 virus. To find potential inhibitors, a total of 2568 drugs were screened. Promacta, tucatinib, and lurasidone were identified as promising hits in the DrugBank database. According to the calculations of MM-GBSA, tucatinib (−54.11 kcal/mol) and Promacta (−56.20 kcal/mol) occupied the active site of neuraminidase with a higher binding affinity than the standard drug peramivir (−49.09 kcal/mol). Molecular dynamics (MD) simulation studies showed that the C-α atom backbones of the complexes of tucatinib and Promacta neuraminidase were stable throughout the simulation period. According to ADME analysis, the hit compounds have a high gastrointestinal absorption (GI) and do not exhibit properties that allow them to cross the blood–brain barrier (BBB). According to the in silico toxicity prediction, Promacta is not cardiotoxic, while lurasidone and tucatinib show only weak inhibition. Therefore, we propose to test these compounds experimentally against the influenza H7N9 virus. The investigation and validation of these potential H7N9 inhibitors would be beneficial in order to bring these compounds into clinical settings.     

Experimental extraction of stern-layer capacitance in biosensor detection using silicon nanowire field-effect transistors

Accurate diagnose of a disease in the early stage is critical to treat the disease properly. To this end, a multitude of biosensors with advanced technologies have been developed to detect the number of biomolecules precisely. In this work, we propose a method for extracting the Stern layer capacitance (C_stern) using the experimental data of silicon nanowire ion-sensitive field-effect transistors (ISFETs) to help improve the accurate detection of target molecules. The proposed method was applied to both pH and virus sensing scheme, and the C_stern value of pH and a virus were extracted as 32 and 26 μF/cm², respectively. These findings indicated that the extracted C_stern was affected by the size of the ion and protein, which also was verified by a computer-aided simulation. These insights would be useful in the development of charge-based ISFET biosensors.     

金刚烷胺硝酸盐的晶体结构

报道了金刚烷胺硝酸盐(三环[3,3,1,11,7]癸烷-1-胺硝酸盐,C10H18N2O3,Mr = 214.26)的晶体结构。该晶体属于正交晶系,空间群为P212121, 晶胞参数:a = 6.380(1),b = 7.349(2),c = 22.801(5) ,V = 1069.0(4) 3,m(MoKa) = 0.098 mm-1,Z = 4,F(000) = 464,Dc =1.331 g/cm3。对于1172 (I ≥2s(I))个可观察衍射点,最终偏离因子R = 0.0310,wR = 0.0757。该晶体由金刚烷铵阳离子和硝酸根阴离子组成,金刚烷基为由椅式构象组成的一个稳定的三环结构。由于氢键作用,晶体呈二维平面无限结构。     

Influenza virus pathogenicity regulated by host cellular proteases,cytokines and metabolites,and its therapeutic options

Influenza A virus (IAV) causes significant morbidity and mortality. The knowledge gained within the last decade on the pandemic IAV(H1N1)2009 improved our understanding not only of the viral pathogenicity but also the host cellular factors involved in the pathogenicity of multiorgan failure (MOF), such as cellular trypsin-type hemagglutinin (HA₀) processing proteases for viral multiplication, cytokine storm, metabolic disorders and energy crisis. The HA processing proteases in the airway and organs for all IAV known to date have been identified. Recently, a new concept on the pathogenicity of MOF, the “influenza virus–cytokine–trypsin” cycle, has been proposed involving up-regulation of trypsin through pro-inflammatory cytokines, and potentiation of viral multiplication in various organs. Furthermore, the relationship between causative factors has been summarized as the “influenza virus–cytokine–trypsin” cycle interconnected with the “metabolic disorders–cytokine” cycle. These cycles provide new treatment concepts for ATP crisis and MOF. This review discusses IAV pathogenicity on cellular proteases, cytokines, metabolites and therapeutic options.