引发2009年流感暴发的H1N1新型流感病毒的研究进展

引起流感世界性大流行的主要原因与流感病毒表面抗原血凝素(HA)和神经氨酸酶(NA)频发的变异有很大关系,抗原的变异使得流感病毒可以逃逸机体的免疫防御,而且使许多应用中的疫苗失去防御效果。综述2009年世界暴发的H1N1新型流感病毒的结构在进化过程中发生的变异,有助于增加人们对流感病毒的了解,从而有效的治疗和预防流感大流行。     

Molecular characterization of avian-like H1N1 swine influenza a viruses isolated in Eastern China, 2011

Currently, three predominant subtypes of influenza virus are prevalent in pig populations worldwide: H1N1, H3N2, and H1N2. European avian-like H1N1 viruses, which were initially detected in European pig populations in 1979, have been circulating in pigs in eastern China since 2007. In this study, six influenza A viruses were isolated from 60 swine lung samples collected from January to April 2011 in eastern China. Based on whole genome sequencing, molecular characteristics of two isolates were determined. Phylogenetic analysis showed the eight genes of the two isolates were closely related to those of the avian-like H1N1 viruses circulating in pig populations, especially similar to those found in China. Four potential glycosylation sites were observed at positions 13, 26, 198, 277 in the HA1 proteins of the two isolates. Due to the presence of a stop codon at codon 12, the isolates contained truncated PB1-F2 proteins. In this study, the isolates contained 591Q, 627E and 701N in the polymerase subunit PB2, which had been shown to be determinants of virulence and host adaptation. The isolates also had a D rather than E at position 92 of the NS1, a marker of mammalian adaptation. Both isolates contained the GPKV motif at the PDZ ligand domain of the 3′ end of the NS1, a characteristic marker of the European avian-like swine viruses since about 1999, which is distinct from those of avian, human and classical swine viruses. The M2 proteins of the isolates have the mutation (S31N), a characteristic marker of the European avian-like swine viruses since about 1987, which may confer resistance to amantadine and rimantadine antivirals. Our findings further emphasize the importance of surveillance on the genetic diversity of influenza A viruses in pigs, and raise more concerns about the occurrence of cross-species transmission events.     

Plasma proteomic analysis of patients infected with H1N1 influenza virus

This study profiled the plasma proteins of patients infected by the 2011 H1N1 influenza virus. Differential protein expression was identified in plasma obtained from noninfected control subjects (n = 15) and H1N1‐infected subjects (n = 15). Plasma proteins were separated by a 2DE large gel system and identified by nano‐ultra performance LC‐MS. Western blot assays were performed to validate proteins. Eight plasma proteins were upregulated and six proteins were downregulated among 3316 plasma proteins in the H1N1‐infected group as compared with the control group. Of 14 up‐ and downregulated proteins, nine plasma proteins were validated by Western blot analysis. Putative protein FAM 157A, leucine‐rich alpha 2 glycoprotein, serum amyloid A protein, and dual oxidase 1 showed significant differential expression. The identified plasma proteins could be potential candidates for biomarkers of H1N1 influenza viral infection. Further studies are needed to develop these proteins as diagnostic biomarkers.     

甲型H1N1流感病毒佐剂疫苗小鼠免疫效果

为了探讨甲型H1N1流感病毒氢氧化铝佐剂疫苗对小鼠的免疫作用及对小鼠繁殖性能的影响,以不同剂量、不同免疫程序免疫小鼠后定期采血;用血凝抑制(HI)方法检测血清H1N1流感病毒HI抗体滴度,观察H1N1流感病毒佐剂疫苗对小鼠受孕、产仔、哺乳的影响;比较孕鼠及非孕鼠的抗体滴度,免疫后孕鼠所产仔鼠的体重及H1N1胎传抗体水平。结果显示,以0.5μg组开始的不同剂量、不同免疫程序均可使小鼠产生90倍以上水平的H1N1流感病毒抗体;免疫后的小鼠不影响受孕、产仔及哺乳;仔鼠保护性抗体可持续1个月以上。H1N1流感病毒佐剂疫苗是一种高免疫原性的制剂,用低剂量免疫,即可产生90倍以上持续时间较长的保护性抗体。这种佐剂疫苗对小鼠的繁殖性能无明显影响,免疫产生的抗体经胎盘可垂直传递给仔鼠。     

Functional association between influenza A (H1N1) virus and human

Influenza A (H1N1) virus is a severe threat worldwide. It is important to gain a better understanding of the mechanism of the infection. In the paper, we established a computational framework to investigate the crosstalk between the virus and the host, by finding out the proteins that the virus is attacking. The targeted proteins were predicted by taking human proteins laid on the same GO functions or processes as the virus proteins. One hundred and one core proteins were identified. The results provide some knowledge of the possible biological processes and molecular interactions caused by the viral infection, including the host responses.     

H5N1亚型禽流感病毒进化的研究进展

由H5N1流感病毒引起的高致病性禽流感,在禽类之间广泛传播。当人类接触这些禽类时,可能会被感染并产生严重的呼吸道症状,且死亡率高达60%。血凝素(hemagglutinin,HA)是H5N1病毒中和抗体的主要抗原,为了便于对病毒的HA突变进行研究,根据HA遗传基因的差异远近,所有的H5病毒株都被划分在20个分支内。对于H5N1病毒进化的研究在禽流感疫苗的研制、禽流感大流行的预防等方面均具有重要意义。现对禽流感、H5N1病毒特征、血凝素的结构功能、H5N1病毒的分支以及病毒进化的研究进行概述。     

一株2011年出现的季节性甲型H1N1流行性感冒病毒血凝素基因特性的研究

本文通过比较2011年分离培养的1株季节性甲型H1N1流行性感冒(简称流感)病毒(A/Shanghai/1167/2011(H1N1))与历年季节性甲型H1N1流感病毒的血凝素(HA)基因,追溯该病毒的基因变异与来源,探讨该毒株的出现对流感防控工作的意义.采用反转录-聚合酶链反应(RT-PCR)方法扩增病毒的HA和神经氨酸酶(NA)片段,并进行测序;应用分子生物学软件对获得的序列进行分析,绘制基因进化树;同时,通过血凝抑制试验检测2011年下半年健康人群中该流感病毒的抗体水平.结果显示,A/Shanghai/1167/2011(H1N1)的HA基因序列与世界卫生组织(WHO)2007～2008年季节性甲型H1N1流感病毒疫苗株A/Brisbane/59/2007(H1N1)最接近,同源性达99.2%,与新型甲型H1N1流感病毒A/California/07/2009疫苗株同源性仅为72.4%.其HA基因裂解位点为PSIQSR↓GLF,尚未出现高致病性的分子特征.HA片段共编码557个氨基酸,有9个潜在的糖基化位点,序列与2009年前WHO疫苗株A/NewCaledonia/20/1999(H1N1)、A/SolomonIslands/3/2006(H1N1)和/Brisbane/59/2007(H1N1)相比,分别有15、12和4处不同,这些差异分布在Sa、Sb、Ca1、Ca2、Cb 5个抗原决定簇的氨基酸差异分别有5、5和2处.该毒株在健康人群血清的抗体阳性率为34.33%,几何平均效价(GMT)为10.38.A/Shanghai/1167/2011(H1N1)是2011年出现在上海地区的一个季节性甲型H1N1流感病毒毒株,其抗原变异与既往季节性甲型H1N1流感病毒相比不大,但在以A(H1N1)pdm09为主要流行株的年份检测到散在发生的既往季节性甲型H1N1流感病毒毒株应当引起重视,其在人群中的抗体水平较低,易引起流行,需要提高对类流感人群中此种毒株的持续监测.     

Influenza A: From highly pathogenic H5N1 to pandemic 2009 H1N1. Epidemiology and clinical features

The last decade has seen the emergence of two new influenza A subtypes and they have become a cause of concern for the global community. These are the highly pathogenic H5N1 influenza A virus (H5N1) and the Pandemic 2009 influenza H1N1 virus. Since 2003 the H5N1 virus has caused widespread disease and death in poultry, mainly in south East Asia and Africa. In humans the number of cases infected with this virus is few but the mortality has been about 60%. Most patients have presented with severe pneumonia and acute respiratory distress syndrome. The second influenza virus, the pandemic H1N1 2009, emerged in Mexico in March this year. This virus acquired the ability for sustained human to human spread and within a few months spread throughout the world and infected over 4 lakh individuals. The symptoms of infection with this virus are similar to seasonal influenza but it currently affecting younger individuals more often. Fortunately the mortality has been low. Both these new influenza viruses are currently circulating and have different clinical and epidemiological characteristics.     

Reassortant swine influenza viruses isolated in Japan contain genes from pandemic A(H1N1) 2009

In 2013, three reassortant swine influenza viruses (SIVs)—two H1N2 and one H3N2—were isolated from symptomatic pigs in Japan; each contained genes from the pandemic A(H1N1) 2009 virus and endemic SIVs. Phylogenetic analysis revealed that the two H1N2 viruses, A/swine/Gunma/1/2013 and A/swine/Ibaraki/1/2013, were reassortants that contain genes from the following three distinct lineages: (i) H1 and nucleoprotein (NP) genes derived from a classical swine H1 HA lineage uniquely circulating among Japanese SIVs; (ii) neuraminidase (NA) genes from human‐like H1N2 swine viruses; and (iii) other genes from pandemic A(H1N1) 2009 viruses. The H3N2 virus, A/swine/Miyazaki/2/2013, comprised genes from two sources: (i) hemagglutinin (HA) and NA genes derived from human and human‐like H3N2 swine viruses and (ii) other genes from pandemic A(H1N1) 2009 viruses. Phylogenetic analysis also indicated that each of the reassortants may have arisen independently in Japanese pigs. A/swine/Miyazaki/2/2013 were found to have strong antigenic reactivities with antisera generated for some seasonal human‐lineage viruses isolated during or before 2003, whereas A/swine/Miyazaki/2/2013 reactivities with antisera against viruses isolated after 2004 were clearly weaker. In addition, antisera against some strains of seasonal human‐lineage H1 viruses did not react with either A/swine/Gunma/1/2013 or A/swine/Ibaraki/1/2013. These findings indicate that emergence and spread of these reassortant SIVs is a potential public health risk.     

Isolation and genetic characterization of avian-like H1N1 and novel ressortant H1N2 influenza viruses from pigs in China

As pigs are susceptible to both human and avian influenza viruses, they have been proposed to be intermediate hosts or mixing vessels for the generation of pandemic influenza viruses through reassortment or adaptation to the mammalian host. In this study, we reported avian-like H1N1 and novel ressortant H1N2 influenza viruses from pigs in China. Homology and phylogenetic analyses showed that the H1N1 virus (A/swine/Zhejiang/1/07) was closely to avian-like H1N1 viruses and seemed to be derived from the European swine H1N1 viruses, which was for the first time reported in China; and the two H1N2 viruses (A/swine/Shanghai/1/07 and A/swine/Guangxi/13/06) were novel ressortant H1N2 influenza viruses containing genes from the classical swine (HA, NP, M and NS), human (NA and PB1) and avian (PB2 and PA) lineages, which indicted that the reassortment among human, avian, and swine influenza viruses had taken place in pigs in China and resulted in the generation of new viruses. The isolation of avian-like H1N1 influenza virus originated from the European swine H1N1 viruses, especially the emergence of two novel ressortant H1N2 influenza viruses provides further evidence that pigs serve as intermediate hosts or “mixing vessels”, and swine influenza virus surveillance in China should be given a high priority.     

重配技术构建高产H1N1型流感疫苗病毒株

目的以经典重配技术制备高产H1N1流感疫苗病毒株。方法以野生型A1/云南昆明/03/2009(H1N1)作为HA及NA基因的供体株,以WHO疫苗株A/Perth/16/2009(H3N2)作为高产基因供体株,共同感染SPF鸡胚,经抗H3及抗N2血清中和筛选法及终末稀释法筛选高产重配H1N1病毒。结果获得一株重配H1N1流感病毒株,病毒血凝滴度为1∶4 096,病毒滴度为7.8 lg EID50/mL,显示为鸡胚高产病毒株;血凝抑制结果为1∶1 024,单向免疫扩散试验结果为阳性,证明抗原性与野生株一致;基因测序结果表明重配株的HA及NA基因序列与野生株序列一致。结论构建了高产重配H1H1流感疫苗病毒株,并应用经典重配技术建立了制备高产流感疫苗病毒株的技术平台。     

On the structure-based design of novel inhibitors of H5N1 influenza A virus neuraminidase (NA)

The structure-based design of novel H5N1 neuraminidase inhibitors is currently a research topic of vital importance owing to both a recent pandemic threat by the worldwide spread of H5N1 avian influenza and the high resistance of H5N1 virus to the most widely used commercial drug, oseltamivir-OTV (Tamiflu). A specific criterion used in this work for determining fully acceptable conformations of potential inhibitors is a previous experimental proposal of exploiting potential benefits for drug design offered by the ‘150-cavity’ adjacent to the NA active site. Using the crystal structure of H5N1 NA (PDB ID: 2hty) as the starting point, in a set of 54 inhibitors previously proposed by modifying the side chains of oseltamivir, 4 inhibitors were identified using two different computational strategies (ArgusLab4.0.1, FlexX-E3.0.1) both to lower the binding free energy (BFE) of oseltamivir and to have partially acceptable conformations. These 4 oseltamivr structure-based analogues were found to adopt the most promising conformations by identifying the guanidinium side chain of Arg156 as a prospective partner for making polar contacts, but none of the modified 4-amino groups of oseltamivir in the 4 favorable conformations was found to make polar contacts with the guanidinium side chain of Arg156. Hence, the structures of two additional inhibitors were designed and shown to further lower the binding free energy of OTV relative to the previous 54 inhibitors. These two novel structures clearly suggest that it may be possible for a new substituent to be developed by functional modifications at position of the 4-amino group of oseltamivir in order to make polar contacts with the guanidinium side chain of Arg156, and thereby enhance the binding of a more potent inhibitor. Several standpoints of vital importance for designing novel structures of potentially more effective H5N1 NA inhibitors are established.     

2009流行性感冒患者血清细胞因子的变化特点

本文旨在通过比较30例2009甲型H1N1流行性感冒(简称流感)患者经奥司他韦治疗前、后血清中细胞因子的变化特点,探讨其可能的发病机制.30例患者分为奥司他韦治疗前组和治疗后组,另选取健康志愿者20例为对照组.采用酶联免疫吸附试验,检测患者血清白细胞介素10(IL-10)、IL-2、IL-8及γ干扰素(IFN-γ)水平...     

2009年中国流行的甲型流感病毒（H1N1）血凝素特征分析

目的研究甲型流感病毒（H1N1）暴发流行以来中国各地甲型流感病毒血凝素（HA）的特征。方法搜索甲型流感病毒（H1N1）暴发流行以来中国各地报道的血凝素（HA）的氨基酸序列,比较当年不同时期血凝素（HA）的氨基酸序列的变化,并比较2009年报道的血凝素（HA）的氨基酸序列和2008年、2007年报道的血凝素（HA）的氨基酸序列作比较,以分析和前2年血凝素（HA）氨基酸序列相比所发生的变化。结果2009年中国各地甲型流感病毒（H1N1）的血凝素（HA）的氨基酸序列（人源）的同源性为99%-100%,但和2008年以及2007年的同源性非常低,分别为70%-77%和71%-90%。结论2009年暴发流行的甲型流感病毒（H1N1）的血凝素氨基酸序列较往年发生了很大程度的变异,这可能是今年甲型流感病毒（H1N1）暴发流行的主要原因。     

A/H6N1亚型禽流感病毒致病性评估及与2009 A/H1N1亚型流感病毒在哺乳动物体内的遗传兼容性

目的探讨人、禽流感病毒在哺乳动物体内的遗传兼容性,为下一步研究H6亚型禽流感病毒重配和致病性变异的分子机制奠定基础。方法野鸭源A/H6N1亚型禽流感病毒A/Mallard/SanJiang/275/2007以101EID50～106EID50的攻毒剂量经鼻内途径感染小鼠,通过临床症状观察、病毒滴定和病理切片观察进行病毒学和组织学两方面检测对小鼠的致病性;同时,将此病毒与2009年A/H1N1流感病毒A/Changchun/01/2009(H1N1)混合感染豚鼠,分析两株病毒在哺乳动物体内的遗传兼容性。每天采集豚鼠鼻洗液并用噬斑纯化技术获得重配病毒,对获得的重配病毒进行全基因组序列的测定。结果 H6N1亚型禽流感病毒能直接感染小鼠,但对小鼠不致死。106EID50的攻毒剂量可有效感染小鼠,攻毒后第5天,小鼠表现出被毛较粗乱、活动减少、体重下降、呼吸急促的临床症状,但至攻毒后第10天开始康复,而对照组(MOCK)小鼠在14 d的观察期内无明显临床症状。病毒滴定结果表明,该病毒主要在小鼠肺脏和鼻甲骨中复制,病毒滴度可达104.5EID50/mL。病理学观察发现感染小鼠肺泡壁增厚,有大量炎性细胞浸润,纤维蛋白渗出并伴有轻微出血;在A/H6N1和A/H1N1混合感染豚鼠的重配实验中,经过三轮噬斑纯化从豚鼠鼻洗液中分离到6株重配病毒,说明A/H6N1亚型禽流感病毒与A/H1N1亚型流感病毒具有很好的遗传兼容性,能在豚鼠体内能发生重配。结论野鸭源A/H6N1亚型流感病毒无需适应就能够感染哺乳动物;该病毒与A/H1N1流感病毒具有很好的遗传兼容性,在哺乳动物体内能够发生基因重配,产生新的重配病毒,其公共卫生意义应引起高度关注。     

The role of nuclear NS1 protein in highly pathogenic H5N1 influenza viruses

The non-structural protein (NS1) of influenza A viruses (IAV) performs multiple functions during viral infection. NS1 contains two nuclear localization signals (NLS): NLS1 and NLS2. The NS1 protein is located predominantly in the nucleus during the early stages of infection and subsequently exported to the cytoplasm. A nonsense mutation that results in a large deletion in the carboxy-terminal region of the NS1 protein that contains the NLS2 domain was found in some IAV subtypes, including highly pathogenic avian influenza (HPAI) H7N9 and H5N1 viruses. We introduced different mutations into the NLS domains of NS1 proteins in various strains of IAV, and demonstrated that mutation of the NLS2 region in the NS1 protein of HPAI H5N1 viruses severely affects its nuclear localization pattern. H5N1 viruses expressing NS1 protein that is unable to localize to the nucleus are less potent in antagonizing cellular antiviral responses than viruses expressing wild-type NS1. However, no significant difference was observed with respect to viral replication and pathogenesis. In contrast, the replication and antiviral defenses of H1N1 viruses are greatly attenuated when nuclear localization of the NS1 protein is blocked. Our data reveals a novel functional plasticity for NS1 proteins among different IAV subtypes.     

新世纪流感大流行的思考

2009年从墨西哥开始暴发了一场席卷全世界的流感疫情．此次大流行的毒株,甲型H1N1病毒,包含了猪源、禽源和人源流感病毒的基因片段．研究该毒株的基因重配、进化历程及其生物学特性,将对防控此次流行具有重要意义．目前,该毒株的遗传进化关系已明确,通过遗传性状分析可获知该毒株可能的生物学性状,但流感大流行动向、毒株遗传变化、毒力及致病性变化仍在密切监控中．流感病毒生态系统具有复杂性,其基因组易突变、易重配、易在自然宿主保存,使得流感大流行存在一定的必然性．正视流感大流行的威胁,积极提高流感病毒在生态系统中的监控,加强流行病学调查,发展疫苗与药物,建立有效公共卫生保障体系,才能降低流感大流行的破坏性．     

新甲型H1N1(2009)病毒的早期分子特征

摘要：【目的】本世纪首次流感大流行的病原属于甲型H1N1流感病毒,在遗传特性和抗原等方面都有别于人群中流行多年的季节性H1N1流感病毒。为了深入了解病毒的遗传特性,跟踪病毒的演化趋势,及时发现具有流行病学意义的变异株,本研究对早期分离的甲型H1N1(2009)病毒的分子特性进行了详细分析。【方法】通过GenBank的流感资源中心下载相关毒株的基因组信息, 序列分析采用DNAStar软件包的EditSeq和MegAlign比较与病毒致病性和宿主特异性相关的氨基酸变化情况。以A/California/07/2009（H1N1）作为新甲型H1N1(2009)的代表株进行详细的分子特征分析。【结果】A/California/07/2009不具备高致病性流感病毒的分子特征;病毒编码的11个蛋白大部分保留有猪流感病毒的分子特征,同时也具有一些禽和人流感病毒的特征;PB1-F2在11aa,57aa和87aa后发生断裂,具有古典猪H1N1和人H1N1双重特点,这是甲型H1N1（2009）病毒一个特有的分子特征。【结论】首次详细分析了新甲型H1N1（2009）病毒的分子特征。随着病毒在人群中的进一步适应和持续存在,这些分子特征将发生变化,应该特别关注这些变化对病毒的传播力和致病性的影响。     

Characterization of a highly pathogenic avian influenza H5N1 virus isolated from an ostrich

The continued spread of a highly pathogenic avian influenza (HPAI) H5N1 virus among poultry and wild birds has posed a potential threat to human public health. An influenza pandemic happens, when a new subtype that has not previously circulated in humans emerges. Almost all of the influenza pandemics in history have originated from avian influenza viruses (AIV). Birds are significant reservoirs of influenza viruses. In the present study, we performed a survey of avian influenza virus in ostriches and H5N1 virus (A/Ostrich/SuZhou/097/03, China097) was isolated. This H5N1 virus is highly pathogenic to both chickens and mice. It is also able to replicate in the lungs of, and to cause death in, BALB/c mice following intranasal administration. It forms plaques in chicken embryo fibroblast (CEF) cells in the absence of trypsin. The hemagglutinin (HA) gene of the virus is genetically similar to A/Goose/Guangdong/1/96(H5N1) and belongs to clade 0. The HA sequence contains multiple basic amino acids adjacent to the cleavage site, a motif associated with HPAI viruses. More importantly, the existence of H5N1 isolates in ostriches highlights the potential threat of wild bird infections to veterinary and public health.     

Molecular character of influenza A/H1N1 2009: Implications for spread and control

The world is experiencing a pandemic of influenza that emerged in March 2009, due to a novel strain designated influenza A/H1N1 2009. This strain is closest in molecular sequence to swine influenza viruses, but differs from all previously known influenza by a minimum of 6.1%, and from prior “seasonal” H1N1 by 27.2%, giving it great potential for widespread human infection. While spread into India was delayed for two months by an aggressive interdiction program, since 1 August 2009 most cases in India have been indigenous. H1N1 2009 has differentially struck younger patients who are naïve susceptibles to its antigenic subtype, while sparing those >60 who have crossreactive antibody from prior experience with influenza decades ago and the 1977 “swine flu” vaccine distributed in the United States. It also appears to more severely affect pregnant women. It emanated from a single source in central Mexico, but its precise geographical and circumstantial origins, from either Eurasia or the Americas, remain uncertain. While currently a mild pandemic by the standard of past pandemics, the seriousness of H1N1 2009 especially among children should not be underestimated. There is potential for the virus, which continues to adapt to humans, to change over time into a more severe etiologic agent by any of several foreseeable mutations. Mass acceptance of the novel H1N1 2009 vaccine worldwide will be essential to its control. Having spread globally in a few months, affecting millions of people, it is likely to remain circulating in the human population for a decade or more.