Antibodies elicited by Newcastle disease virus-vectored H7N9 avian influenza vaccine are functional in activating the complement system

H7N9 subtype avian influenza virus poses a great challenge for poultry industry.Newcastle disease virus(NDV)-vectored H7N9 avian influenza vaccines(NDV_(vec)H7N9)are effective in disease control because they are protective and allow mass administration.Of note,these vaccines elicit undetectable H7N9-specific hemagglutination-inhibition(HI)but high IgG antibodies in chickens.However,the molecular basis and protective mechanism underlying this particular antibody immunity remain unclear.Herein,immunization with an NDV_(vec)H7N9 induced low anti-H7N9 HI and virus neutralization titers but high levels of hemagglutinin(HA)-binding IgG antibodies in chickens.Three residues(S150,G151 and S152)in HA of H7N9 virus were identified as the dominant epitopes recognized by the NDV_(vec)H7N9 immune serum.Passively transferred NDV_(vec)H7N9 immune serum conferred complete protection against H7N9 virus infection in chickens.The NDV_(vec)H7N9 immune serum can mediate a potent lysis of HA-expressing and H7N9 virus-infected cells and significantly suppress H7N9 virus infectivity.These activities of the serum were significantly impaired after heat-inactivation or treatment with complement inhibitor,suggesting the engagement of the complement system.Moreover,mutations in the 150-SGS-152 sites in HA resulted in significant reductions in cell lysis and virus neutralization mediated by the NDV_(vec)H7N9 immune serum,indicating the requirement of antibody-antigen binding for complement activity.Therefore,antibodies induced by the NDV_(vec)H7N9 can activate antibody-dependent complement-mediated lysis of H7N9 virus-infected cells and complement-mediated neutralization of H7N9 virus.Our findings unveiled a novel role of the complement in protection conferred by the NDV_(vec)H7N9,highlighting a potential benefit of engaging the complement system in H7N9 vaccine design.

2014-2018年新疆人感染H7N9禽流感分子流行病学特征分析

目的分析2014-2018年新疆14例人感染H7N9禽流感病例的分子流行病学特征,为防控及治疗提供科学依据。方法提取核酸后采用高通量基因测序技术获得基因组序列,并用生物信息学分析软件对基因组序列进行同源性分析、进化分析、变异位点分析及同源建模。结果14例人感染H7N9禽流感病毒HA基因核苷酸同源性介于97.39%~100%,氨基酸同源性介于98.38%~100%;NA基因核苷酸同源性介于97.73%~100%,氨基酸同源性介于97.73%~100%,均属于长江三角洲谱系和低致病性禽流感病毒,分属于2个亚分支,与A/Hunan/02650/2016疫苗株最为接近。HA蛋白G186V、T160A全部发生了变异,Q226L中13株病毒发生了变异,NA蛋白4个关键的神经氨酸酶抑制剂耐药位点全部未发生变异。M2蛋白S31N和V27A位点全部发生了突变,PB1蛋白T368V位点全部发生了突变,PA蛋白位点K356R全部发生了突变。结论新疆H7N9禽流感病毒具有双受体结合性,对金刚烷胺类药物耐药,对神经氨酸酶抑制剂敏感,可在疾病发生早期及时使用神经氨酸酶抑制剂。需加强禽流感病毒基因组变化的监测,做好基因突变的应对措施。

抗H7N9流感病毒的单克隆抗体与胃组织的交叉反应研究

目的筛选鉴定与胃组织交叉反应的抗H7N9流感病毒的单克隆抗体,初步探讨流感病毒感染会引发肠道相关疾病的可能致病机制。方法利用H7N9流感病毒制备了大量的单克隆抗体,对制备的单克隆抗体运用ELISA方法进行亚型和效价测定,免疫组化对制备的单克隆抗体与组织的反应性进行筛选,巢式PCR分子生物学技术克隆单克隆抗体轻重链可变区序列。结果制备的单克隆抗体H7N9-71和H7N9-78均能与H7N9抗原特异性结合,抗体效价达1∶10~5,免疫组化结果表明H7N9-71、H7N9-78与人的胃组织能发生特异性反应,进一步的研究发现这两株单抗与小鼠胃组织能特异性结合。轻重链可变区序列结果证实二者为两株不同的单抗。结论H7N9流感病毒可能与胃组织之间存在异嗜性抗原,提示流感病毒感染可能与胃肠道疾病的发生存在某些关联。

表达H7N9亚型禽流感病毒HA蛋白的重组血清4型禽腺病毒构建及其免疫效果评估

为构建H7N9亚型禽流感病毒和血清4型禽腺病毒(FAdV-4)的二联疫苗候选株,试验通过CRISPR/Cas9和Cre-Loxp系统,以课题组前期构建的表达EGFP蛋白的重组病毒FAdV4-EGFP为载体,构建能够稳定表达H7N9亚型禽流感病毒血凝素(HA)蛋白的重组血清4型腺病毒;并通过PCR、间接免疫荧光试验(IFA)、Westernblot试验以及SPF鸡保护性试验等方法,探究此重组病毒体外生物学特性并评估其为鸡提供的保护力。结果显示:研究成功构建能稳定表达H7N9禽流感亚型病毒HA蛋白的重组血清4型腺病毒,命名为FAdV4-H7;FAdV4-H7能在LMH细胞高效复制,并能在LMH细胞传代15次后仍能稳定表达HA蛋白;FAdV4-H7不仅高度致弱,而且能诱导机体产生高滴度针对H7N9亚型禽流感病毒HI抗体和FAdV-4的中和抗体,能为SPF鸡提供足够保护来抵抗致死性FAdV-4感染。研究表明,试验成功构建了重组病毒FAdV4-H7,为H7N9亚型禽流感病毒和FAdV-4的联防联控提供了二联苗候选疫苗株。

中国H7N9禽流感遗传演化趋势及防控措施

H7N9禽流感病毒(AIV)感染人类的情况最先出现在中国,而且具有很高的突变性。2013年首次在人类身上分离出的是低致病性H7N9禽流感病毒,发展到2017年,已经出现高致病性H7N9禽流感病毒,严重威胁动物和人类的生命健康安全,同时,还会对社会的稳定和经济发展有一定的影响。综述通过NCBI(National Center for Biotechnology Information)和GISAID数据库收集了中国国内2001~2021年共4641条有关H7N9的数据,拟通过流行病学的角度来说明H7N9禽流感病毒在中国的发生、发展以及在时间、空间和种群间的分布情况,同时总结中国对H7N9所引起的大流行所采取的防控措施,以期为后续的疫情防控措施规划提供依据。

2株2023年禽源H7N9亚型禽流感病毒的分离鉴定及遗传进化分析

为了解H7N9亚型禽流感病毒(Avian influenza virus,AIV)的遗传进化特点,探究我国H7N9亚型AIV的流行特征,试验对2023年采集自四川、河北两地活禽市场禽类咽拭子及泄殖腔拭子进行病原分离鉴定,并对分离株进行全基因组序列测定,进一步构建进化树并分析其遗传演化情况和分子特征。结果显示:共分离2株H7N9亚型AIV,其遗传距离较近,HA基因均属于YRD-B分支;2株AIV的HA蛋白裂解位点均含有连续碱性氨基酸,具有高致病性的分子特征;PB2、HA和NA蛋白均具有哺乳动物适应性突变,其中HA蛋白第226位受体结合位点均由谷氨酰胺(Q)突变为亮氨酸(L),使其能够识别人流感病毒唾液酸受体,并且HA蛋白A27S、I96V、V143T、A169T、I187V和D457N抗原位点发生突变;2株AIV虽均能与Re-4和H7N9rHN7903灭活疫苗免疫血清产生交叉血凝抑制反应,但HI抗体效价较低。研究表明,从活禽市场分离到2株H7N9亚型AIV,其对家禽具有高致病性,且抗原性发生变化。

Genetic and biological properties of H9N2 avian influenza viruses isolated in central China from2020 to 2022

The H9N2 subtype of avian influenza virus(AIV)is widely prevalent in poultry and wild birds globally,and has become the predominant subtype circulating in poultry in China.The H9N2 AIV can directly or indirectly(by serving as a"donor virus")infect humans,posing a significant threat to public health.Currently,there is a lack of in-depth research on the prevalence of H9N2 viruses in Shanxi Province,central China.In this study,we isolated 14 H9N2 AIVs from October 2020 to April 2022 in Shanxi Province,and genetic analysis revealed that these viruses belonged to 7 different genotypes.Our study on animals revealed that the H9N2 strains we identified displayed high transmission efficiency among chicken populations,and exhibited diverse replication abilities within these birds.These viruses could replicate efficiently in the lungs of mice,with one strain also demonstrating the capacity to reproduce in organs like the brain and kidneys.At the cellular level,the replication ability of different H9N2 strains was evaluated using plaque formation assays and multi-step growth curve assays,revealing significant differences in the replication and proliferation efficiency of the various H9N2 viruses at the cellular level.The antigenicity analysis suggested that these isolates could be classified into 2 separate antigenic clusters.Our research provides crucial data to help understand the prevalence and biological characteristics of H9N2 AIVs in central China.It also highlights the necessity of enhancing the surveillance of H9N2 AIVs.

In silico evaluation of kuwanon compounds as antiviral agents targeting H9N2 influenza virus

Background:The threat of avian influenza a subtype avian influenza A(H9N2)virus remains a significant concern,necessitating the exploration of novel antiviral agents.This study employs network pharmacology and computational analysis to investigate the potential of kuwanons,a natural compounds against H9N2 influenza virus.Methods:Leveraging comprehensive databases and bioinformatics tools,we elucidate the molecular mechanisms underlying Kuwanons pharmacological effects against H9N2 influenza virus.Network pharmacology identifies H9N2 influenza virus targets and compounds through integrated protein-protein interaction and Kyoto Encyclopedia of Genes and Genomes analyses.Molecular docking studies were performed to assess the binding affinities and structural interactions of Kuwanon analogues with key targets,shedding light on their potential inhibitory effects on viral replication and entry.Results:Compound-target network analysis revealed complex interactions(120 nodes,163 edges),with significant interactions and an average node degree of 2.72.Kyoto Encyclopedia of Genes and Genomes analysis revealed pathways such as Influenza A,Cytokine-cytokine receptor interaction pathway in H9N2 influenza virus.Molecular docking studies revealed that the binding free energy for the docked ligands ranged between-5.2 and-9.4 kcal/mol for the human interferon-beta crystal structure(IFNB1,Protein Data Bank:1AU1)and-5.4 and-9.6 kcal/mol for Interleukin-6(IL-6,PDB:4CNI).Conclusion:Our findings suggest that kuwanon exhibits promising antiviral activity against H9N2 influenza virus by targeting specific viral proteins,highlighting its potential as a natural therapeutic agent in combating avian influenza infections.

Risk assessment on the epidemics of human infection with a novel avian influenza A (H7N9) virus in Jiangsu Province, China

A novel avian influenza A （H7N9） virus was discovered in February 2013 in China and has resulted in more than 100 comfirmed human infections including 26 fatal cases as of May 2, 2013. The situation raises many ur- gent questions and global public health concerns. In this study, epidemiologic characteristics of infected human cases in Jiangsu province were analyzed and risk assessment was undertaken based on the information available. Briefly, it is highly unlikely that a pandemic of human infection with avian influenza A （HTN9） virus will happen in Jiangsu Province in the near future. Iia the end, some measures are recommended to prevent the situation from becoming worse.

Clinical Study of Mesenchymal Stem Cell Treatment for Acute Respiratory Distress Syndrome Induced by Epidemic Influenza A(H7N9) Infection: A Hint for COVID-19 Treatment

2013年,H7N9病毒在哺乳动物宿主之间迅速传播,并具有人与人之间传播的风险。患者表现为重症肺炎、急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS)和呼吸衰竭。间充质干细胞(mesenchymal stem cell,MSC)移植在病毒性肺炎的治疗中有广阔的前景,并于2013年作为应急性治疗方法来治疗H7N9感染的ARDS。该研究在单中心开展,为开放式临床研究。根据自愿和知情同意的原则,17例H7N9感染的ARDS患者移植同种异体经血来源的MSC作为治疗组,44例H7N9感染的ARDS患者作为对照组。与对照组相比,MSC移植显著降低了ARDS病死率(MSC治疗组和对照组死亡率分别为17.6%和54.5%)。此外,在对4名MSC移植患者进行为期5年的随访中,未发现MSC移植产生有害影响。总体而言,该研究结果表明MSC移植显著提高了H7N9感染的ARDS的存活率,并为开展临床前和临床应用MSC治疗H7N9感染的ARDS的研究提供了理论基础。由于H7N9和新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)临床表现相似(如ARDS和呼吸衰竭),并继发多器官功能障碍,因此基于MSC的疗法可能为COVID-19所致的ARDS患者获益。

Characterization of Avian Influenza A(H7N9) Virus Prevalence in Humans and Poultry in Huai′an,China：Molecular Epidemiology,Phylogenetic,and Dynamics Analyses

Objective To trace the source of human H7N9 cases in Huai＇an and elucidate the genetic characterization of Huai＇an strains associated with both humans and birds in live poultry market.Methods An enhanced surveillance was implemented when the first human H7N9 case was confirmed in Huai＇an.Clinical specimens,cloacal swabs,and fecal samples were collected and screened by real-time reverse transcription-polymerase chain reaction（RT-PCR） for H7N9 virus.The positive samples were subjected to further RT-PCR and genome sequencing.The phylodynamic patterns of H7N9 virus within and separated from Huai＇an and evolutionary dynamics of the virus were analyzed.Results Six patients with H7N9 infection were previously exposed to live poultry market and presented symptoms such as fever（〉38.0 °C） and headaches.Results of this study support the hypothesis that live poultry markets were the source of human H7N9 exposure.Phylogenetic analysis revealed that all novel H7N9 viruses,including Huai＇an strains,could be classified into two distinct clades,A and B.Additionally,the diversified H7N9 virus circulated in live poultry markets in Huai＇an.Interestingly,the common ancestors of the Huai＇an H7N9 virus existed in January 2012.The mean nucleotide substitution rates for each gene segment of the H7N9 virus were（3.09-7.26）×10-3 substitutions/site per year（95% HPD：1.72×10-3 to 1.16×10-2）.Conclusion Overall,the source of exposure of human H7N9 cases in Huai＇an was live poultry market,and our study highlights the presence of divergent genetic lineage of H7N9 virus in both humans and poultry specimens in Huai＇an.

Development of a real-time RT-PCR method for the detection of newly emerged highly pathogenic H7N9 influenza viruses

In 2013, a human influenza outbreak caused by a novel H7N9 virus occurred in China. Recently, the H7N9 virus acquired multiple basic amino acids at its hemagglutinin（HA） cleavage site, leading to the emergence of a highly pathogenic virus. The development of an effective diagnostic method is imperative for the prevention and control of highly pathogenic H7N9 influenza. Here, we designed and synthesized three pairs of primers based on the nucleotide sequence at the HA cleavage site of the newly emerged highly pathogenic H7N9 influenza virus. One of the primer pairs and the corresponding probe displayed a high level of amplification efficiency on which a real-time RT-PCR method was established. Amplification using this method resulted in a fluorescent signal for only the highly pathogenic H7N9 virus, and not for any of the H1–H15 subtype reference strains, thus demonstrating high specificity. The method detected as low as 39.1 copies of HA-positive plasmid and exhibited similar sensitivity to the virus isolation method using embryonated chicken eggs. Importantly, the real-time RT-PCR method exhibited 100% consistency with the virus isolation method in the diagnosis of field samples. Collectively, our data demonstrate that this real-time RT-PCR assay is a rapid, sensitive and specific method, and the application will greatly aid the surveillance, prevention, and control of highly pathogenic H7N9 influenza viruses.

H7N9 influenza-the laboratory presentations: A letter to editor

To the editor,1.Introduction to new H7N9 bird flu Influenza virus infection is an important group of respiratory infectious disease.Several groups of influenza viruses can cause human infections.However,in the recent years,there are many newly emerging influenza infections,which have never been previously seen in human.Crossing species from animal to human lead

Receptor binding specificity and sequence comparison of a novel avian-origin H7N9 virus in China

Avian influenza such as H5N1 could infect humans and cause great health concern due to its high mortality rate. In March 2013, a novel reassortant avian-origin influenza A (H7N9) virus was found in several patients with severe respiratory illness in China. Since then, at least 82 people in China have been infected with this new virus and 17 have died from this virus. The question of how these people were infected with this virus and whether this virus will spread among people remains an urgent topic for research. This study took an early investigation of this virus ?by comparing the collected viral genome sequences ?of 2013 H7N9 inChinaagainst those of previous avian H7N9 and examined the receptor binding specificity of this new virus. This virus was found to be very different from the previous avian H7N9 viruses and surprisingly many of the internal proteins of 2013 H7N9 from the avian and human hosts in China were either identical or similar. Our analysis of the HA protein of this virus implied that the current strains of 2013 H7N9 inChina displayed avian type receptors as their primary binding preference and human type receptors as secondary. For pandemic risk assessment, we also detected 23 mutations, including a few well known for host adaptation, in the HA1 domain of the HA protein from this virus. Each mutation was quantified for its impact on the recaptor binding selection using a bioinformatics approach. Collectively these current mutations tended to decrease the HA binding affinity for avian type recaptors and increase that for human type receptors, which could enhance the ability of this virus to infect humans.

H7N9病毒的来源和重组模式

目的通过序列分析揭示H7N9病毒的来源和重组产生模式。方法收集H7N9序列,运用BLAST、MEGA5.0等生物信息学软件分析序列相似性、多序列比对、构建进化树,确定H7N9病毒各节段序列的亲缘序列,模拟H7N9重组产生方式。结果系统进化树显示HA、NA、PB2和NS节段最近缘关系序列只有一个;而PB1、PA、NP和MP节段序列,分布于不同的两个分枝。通过组合分析亲缘序列,可以将目前流行的H7N9病毒分为5型:A、B、A/Shanghai/1/2013-H7N9、A/Pigeon/Shanghai/S1069-H7N9和A/Zhejiang/HZ1/2013-H7N9。A型又可以分为A1和A2亚型。结论通过对序列的组合分析,推测此次H7N9病毒流行至少由5个病毒经过4次重组产生,产生两个主要流行株A和B型。A1和A2亚型的出现是同一次重组过程中产生两株不同产物;A/Pigeon/Shanghai/S1069-H7N9是A型H7N9病毒在流行期间与当地H9N2病毒的再一次重组产生。A/Zhejiang/HZ1/2013-H7N9是A2亚型和B型重组后产生的混合型。

H7N9亚型禽流感病毒RT-PCR检测方法建立

【目的】2013年3月,中国国家卫生和计划生育委员会宣布在上海、安徽地区发现了人感染H7N9亚型流感病毒事件,由于这种新型重组H7N9流感病毒未曾有过感染人或者动物的报道,因此出现了一系列亟待解决的问题,引起了全世界范围的广泛关注。根据H7N9亚型禽流感病毒HA和NA核苷酸序列,设计并合成靶基因为HA和NA的2对引物,建立快速检测H7N9亚型禽流感病毒的一步法RT-PCR检测方法。【方法】根据测序结果,用DNAStar生物软件进行同源性分析比较,选出H7和N9基因中高度保守且特异的核苷酸区域,用oligo6.0软件设计针对H7和N9基因的引物。用Trizol LS提取RNA,采用一步法Access RT-PCR扩增反应液,建立了一步法检测H7N9亚型禽流感病毒RT-PCR方法。以H7N9亚型流感病毒为阳性对照,其他亚型流感病毒以及新城疫、传染性支气管炎、传染性法氏囊等其他禽病病原作为阴性对照,按所建立的反应体系和反应程序进行RT-PCR反应,验证所建立方法的特异性。对病毒含量为106.5 EID50·m L-1的H7N9亚型禽流感病毒尿囊液依次进行10倍倍比稀释,提取RNA用RT-PCR方法检测,评价其敏感性。另外,采取双盲试验用荧光定量RT-PCR对该方法进行了比对验证。【结果】用H7亚型特异性引物检测H1—H15亚型禽流感病毒和鸡新城疫病毒等其他禽病病原,除H7亚型流感病毒外,其他样品均为阴性;用N9亚型特异性引物检测N1—N9亚型禽流感病毒和其他禽病病原,仅当前流行的H7N9亚型AIV样品有特异性目的条带,与其他N1—N9亚型禽流感病毒和鸡新城疫病毒等其他禽病病原均无交叉反应。通过对H7N9亚型禽流感病毒尿囊液进行10倍倍比稀释检测,证实该方法最低检出量为1.4×102.5 EID50·m L-1,并可以从阳性棉拭子浸出液中扩增出目的基因片段。【结论】该RT-PCR方法具有特异性强和准确率高的特点,可以作为H7N9亚型AIV核酸检测的一种有效候选方法。

H7N9禽流感病毒对人类致病的分子基础分析

【目的】了解H7N9禽流感病毒对人类致病的分子特征,为更好地预防与治疗H7N9人禽流感提供科学依据。【方法】从GISAID数据库中下载中国2013年分离的所有H7N9禽流感病毒株的基因及蛋白序列,并从NCBI数据库中下载其他相关的流感病毒序列,运用生物信息学软件分析H7N9禽流感病毒基因的系统进化特征、受体结合位点、宿主特异位点、飞沫传播关键氨基酸位点、致病及毒力相关位点、耐药性位点及潜在糖基化位点等的变异情况。【结果】2013年中国流行的H7N9禽流感病毒为四源重组病毒,所有基因片段均来源于禽类,不含任何人流感病毒基因;病毒HA的受体结合位点发生了2个关键氨基酸的变异(G186V和Q226L);在与飞沫传播有关的关键氨基酸位点中,个别氨基酸已发生了变异(T160A、Q226L);该病毒具有8个毒力增强位点;所有分离株的M2均发生了S31N变异;分离株A/Shanghai/1/2013的NA的耐药位点发生了R294K变异;所有毒株的潜在糖基化位点均相对保守。【结论】H7N9禽流感病毒为四源重组的新型禽流感病毒。该病毒具有与人呼吸道上皮细胞SAa-2,6 Gal受体结合的分子基础,但目前尚未获得经飞沫传播的充分条件,人传人的可能性不大。该病毒具有低致病性禽流感病毒的分子特征,表明对禽类致病性不强,但其对人类呈高致病性,这可能与其毒力位点的特征有关。所有分离毒株均发生了对离子通道抑制剂金刚烷胺类药物的耐药性突变,个别毒株已发生了对神经氨酸酶抑制剂奥司他韦(达菲)的耐药性突变。

福建省首例人感染H7N9禽流感病例实验室诊断和病毒序列分析

目的应用real-time RT-PCR和病毒序列测定等方法对福建省首例人感染H7N9禽流感病例开展实验室诊断。方法采集人感染H7N9禽流感病例呼吸道标本并提取RNA,分别采用甲乙型流感通用引物和探针、季节性流感(包括H3N2、H1N1、H1N1pdm)特异性引物和探针以及H7N9特异性引物和探针进行real-time RT-PCR检测。利用自行设计的引物扩增病毒基因组节段,测定并分析病毒基因序列。结果 real-time RT-PCR结果表明,应用甲型通用引物扩增结果阳性,乙型及季节性流感(包括H3N2、H1N1以及H1N1pdm)扩增结果均为阴性,特异性H7N9亚型流感病毒扩增结果阳性。序列测定获得的病毒4个节段的序列与已公布的人感染H7N9禽流感病毒序列高度一致。结论病例呼吸道标本中存在人感染H7N9禽流感病毒,病毒的基因与近期国内流行的人感染H7N9禽流感病毒高度类似。

人感染H7N9禽流感流行特征与防控策略

2013年3月31日中国大陆出现新型禽流感疫情,此次的H7N9禽流感病毒为全球首次发现的新亚型流感病毒,可能由3种流感病毒重组后产生。截至5月31日,我国内地共报告确诊病例131例,死亡39例。而在上海市报告的33例确诊病例中,29例发病于4月6日上海市关闭活禽交易市场前,其余4例发病于关闭后的第一个潜伏期内。33例病例中60岁以上患者占66.7%(22/33);15例死亡病例中,60岁以上患者占80%(12/15);90.91%(30/33)的病例具有可疑的动物或环境暴露史。此次疫情呈散发,虽然出现了2起家庭聚集性病例,但目前还没有明确的人传人的证据。疫情发生后,上海市人民政府适时启动了流感流行应急预案Ⅲ级响应,通过突发公共卫生事件应急响应、关闭全市活禽交易、健康教育、风险沟通等手段,及时有效地控制了疾病的传播。本文分析这次疫情防控工作的得失并提出建议,供今后的防疫工作借鉴参考。

H7N9事件网络舆情分析及其对突发公共卫生事件应对的启示

目的:分析H7N9事件网络舆情的发展演变规律,为突发公共卫生事件的处置提供参考。方法:以百度指数为工具,选择全国和江浙沪皖作为研究区域,研究时间跨度为2013年3月至6月H7N9事件的网络舆情状况。结果:网络舆情经历了明显的"从无到有,达到高峰,渐渐平息"的状态,网络关注热度与事件处置和信息发布密切关联。结论:政府在突发公共卫生事件处置中,应保证信息及时透明发布,对网络舆情及时监测预警并积极引导网络舆论。