2018-2019年克拉玛依市新甲型H1N1流感病毒NA基因分析

目的 分析新疆克拉玛依市新甲型H1N1流感病毒NA基因特征及变异情况.方法 采集2018年1月-2019年12月哨点医院流感样病例咽拭子,经MDCK细胞完成流感病毒分离后,随机抽取26株分离株测定其NA基因序列,并与疫苗株进行序列比对和分析.结果 与疫苗株A/Michigan/45/2015 NA基因核苷酸相比,2018年分离株与其同源性为98.56％～99.28％,2019年分离株与其同源性为98.35％～98.71％;26株分离株与同期国内其他地区代表株和疫苗株A/Michigan/45/2015在同一进化分支;分离株T180699较疫苗株A/Michigan/45/2015少1个糖基化位点(42～44位),分离株T190041发生了I223V位点变异.结论 相对于疫苗株A/Michigan/45/2015,2018-2019年克拉玛依市新甲型H1N1流感病毒NA基因抗原决定簇、糖基化位点和耐药相关位点已有改变;应继续加强流感监测,密切关注其基因变异情况.     

新甲型H1N1流感病毒与流感大流行防治研究进展

由于甲型流感病毒基因高度变异的特点,导致其对不同种属宿主亲和力、毒力、免疫原性、抗药性不断发生变化,全球新型流感大流行的风险时刻存在.因此,应加强流感特别是重症流感发病机制和有效干预措施研究,从疫苗研制、开发新型抗病毒药、加强综合治疗,特别是调节宿主免疫反应等多个方面着手,为应对可能爆发的流感大流行提供对策.     

甲型H1N1流感病毒基因特征及耐药性研究

目的研究甲型H1N1流感病毒的基因特征和变化规律,为流感疫苗评价提供依据。方法选取2009年6月-2013年4月本院分离出的15株甲型H1N1病毒分离株,提取病毒RNA进行反转录。采用PCR方法扩增15株甲型H1N1流感病毒HA和NA全基因并进行测序分析。利用软件Bioedit和MEGA软件对序列进行拼接,绘制种系发生树,采用邻位相临法构建进化树。结果 15株甲型H1N1流感病毒均为低致病性病毒,对神经氨酸酶抑制剂敏感,对金刚烷胺类呈耐药性。实验毒株HA基因序列与国内和国外毒株同源性为99.1%~99.7%。该地区流感毒株抗原变异程度较大,其中毒株HA发生14个氨基酸点位改变,分别为:A215E,D127E,E235K,E374K,G170E,H138R,L161I,I321V,L191I,P83S,R45K,S185T,S203T和V234I。其中第83位和第321位与国内代表株相同,但是与国外代表株不同。NA发生15个氨基酸点位改变,分别为A20V,N44S,V83M,V106I,E128G,H144Y,I188T,V241I,S247N,N248D,S334N,N369K,N449K,D451G和G454S。其中所有毒株均发生V106I和S247N的变化。结论通过对HA和NA基因序列对比分析,该地区流感疫苗对当地居民有保护作用,但是毒株与疫苗株间发生相对抗原漂移,需要进一步观察毒株变异情况。     

甲型H1N1与季节性H1N1流感病毒血凝素基因比较分析

目的分析泰安市2008～2009年度季节性流感与2009年度甲型H1N1流感病原学检测结果 ,比较季节性H1N1与甲型H1N1血凝素基因变异情况。方法选择国家级流感监测哨点医院以及暴发疫情的疫点,采集流感样病例的鼻咽拭子标本,通过RealtimePCR进行病毒检测,用MDCK细胞进行病毒分离,通过RT-PCR扩增血凝素HA1片段的基因并测序,利用生物信息学进行序列分析。结果 2008～2009年共检测鼻咽拭子标本283份,分离出流感病毒33株,分离阳性率为11.67%,其中季节性H1N1亚型31株。2009年5月1日～12月31日,检测鼻咽拭子标本996份,流感核酸检测阳性417份,阳性率为41.86%,其中甲型H1N1337份,季节性H1N1亚型1份。6株季节性H1N1病毒均在多个氨基酸位点上发生变异,与疫苗株A/Brisbane/59/2007(H1N1)比较,有11个位点发生了突变,其中5个位点位于抗原决定簇上;测序成功的6株甲型H1N1病毒在多个氨基酸位点发生变异,与疫苗株A/California/07/2009(H1N1)比较,有6个位点发生突变,其中1个位点位于抗原决定簇的B区。结论 2008～2009年度季节性H1N1为优势株,甲流暴发后,甲型H1N1成为绝对优势毒株。季节性H1N1分离株有多处氨基酸替换,抗原决定簇B区变异频繁;甲型H1N1病毒分离株的基因有变异,但关键位点第222位仍为D(天冬氨酸),与疫苗株相比抗原决定簇的关键位点变化不大。     

甲型H1N1流感血清流行病学研究进展

甲型H1N1流感（甲流）病毒是4源重配病毒,由经典猪流感病毒、欧洲猪流感病毒、禽流感病毒和人流感病毒重配而成,人群对甲流病毒普遍易感。2009年6月11日,世界卫生组织（WHO）宣布将甲流流行警告级别提升为6级,全球进入流感大流行阶段。     

甲型H1N1流感病毒的发病机制

甲型H1N1流感病毒概述：研究表明这种病毒基因组由禽流感、猪流感和人流感病毒基因混合而成，可看作是一种杂交体，是一种新型的甲型H1N1流感病毒，它所引起的流感具有高度传染、传播迅速、易流行的特点。甲型H1N1流感患者为主要传染源，甲型H1N1流感主要通过飞沫或气溶胶经呼吸道传播，也可通过口腔、鼻腔、眼睛等处黏膜直接或间接接触传播，接触患者的呼吸道分泌物、体液和被病毒污染的物品亦可能造成传播。     

2009-2013年无锡地区新甲型H1N1流感病毒基因变异分析

目的了解2009～2013年无锡地区新甲型H1N1流感病毒血凝素（HA）和神经氨酸酶（NA）的基因变异情况。方法选取2009～2013年哨点医院分离的新甲型H1N1流感病毒，进行HA和NA核苷酸序列测定，用Bioedit和MEGA version4．0分析软件进行基因种系进化特性分析。结果无锡地区2009～2013年种型H1N1流感病毒HA基因序列的同源性为98．9％～99．5％；氨基酸序列分析显示，无锡地区分离株第203位与国内、国际代表株比较发生氨基酸替换：S→T；第83位和321位与国内代表株相同，而与国际代表株不同，分别为S→P、V→I。NA基因序列与国内、国际代表株同源性为99．2％～99．8％；第87位和349位与国内代表株相同，而与国际代表株不同，分别为R→Q、D→G。结论通过对HA和NA基因序列的比对分析，2009-2013年无锡地区新甲型H1N1流感病毒流行株基因序列与国内、国际代表株高度同源。表明该地区近期不会发生新甲型H1N1流感大流行。     

福建省2009年甲型H1N1流感病毒NA基因特征及对达菲的耐药性

目的监测福建省甲型H1N1流感病毒NA基因的变化以及对达菲的耐药情况,为临床诊疗和疾病控制提供参考依据。方法从福建省流感监测网络中随机选取23株甲型H1N1流感病毒,经病毒核酸提取和一步法RT-PCR扩增,获得NA基因片段,双向测定核苷酸序列,分析NA基因序列和重要氨基酸位点特征。结果 23株甲型H1N1流感病毒NA片段基因与A/California/07/2009(H1N1)代表株的核苷酸序列进行比较,同源性高达98.1%以上;23株毒株NA蛋白第275位氨基酸均为组氨酸。结论随机选取的23株甲型H1N1流感病毒NA基因片段保持高度同源并且对达菲仍然敏感。随着国内外达菲耐药株的不断出现,应加强耐药性监测,为制定应对甲型H1N1流感流行措施提供参考。     

甲型H1N1流感病毒HA基因的原核表达及免疫反应性分析

目的构建甲型H1N1流感病毒HA基因的原核表达质粒,获得融合表达蛋白,并对表达蛋白的免疫反应性进行分析。方法人工合成A/California/05/2009 H1N1流感病毒的HA基因,以合成基因为模板,通过PCR方法扩增出去除信号肽的HA部分基因片段,然后将去除信号肽的HA基因克隆至pET30a(+)原核表达载体中,构建出原核表达质粒,再将重组质粒转化E.coliBL21(DE3)表达菌株;重组菌经IPTG诱导后,收集菌体进行SDS-PAGE电泳分析,Western blot分析表达产物的免疫反应性。结果获得了HA基因的原核表达重组菌,细菌经IPTG诱导表达后,SDS-PAGE分析可见约67.4 ku大小的目的蛋白表达条带,Western blot结果显示,表达产物与人甲型H1N1流感患者阳性血清具有反应性。结论成功表达出甲型H1N1流感病毒的HA蛋白,该蛋白具有良好的免疫反应性,为甲型H1N1流感的快速诊断方法的建立提供了生物材料。     

猪流感病毒和新型甲型流感H1N1病毒

2009年3～4月,墨西哥和美国部分地区相继报告了一些不寻常的人流感样病例。核酸序列分析显示了毒株来源于猪流感病毒（SIV）,流行病学调查发现这些病例没有猪接触史,并且存在人与人感染。因此4月24日世界卫生组织（WHO）正式通报了这次疫情,并首次将其定义为全球流感大流行3级预警,随后在一周内又相继升级为4级和5级。由于引起这次爆发的毒株以前在猪和人标本中均未出现过,一度因为被称为猪流感病毒而导致一些误解,后更名为甲型流感病毒H1N1（为了与季节性甲型流感病毒H1N1区别,本文将引起这次大流行的毒株称为新型甲型流感病毒）。那么,什么是猪流感病毒？猪流感病毒能否感染人？     

Transmission of influenza A(H1N1) 2009 pandemic viruses in Australian swine

Please cite this paper as: Deng et al. (2012). Transmission of influenza A(H1N1) 2009 pandemic viruses in Australian swine. Influenza and Other Respiratory Viruses 6(3), e42–e47. Background Swine have receptors for both human and avian influenza viruses and are a natural host for influenza A viruses. The 2009 influenza A(H1N1) pandemic (H1N1pdm) virus that was derived from avian, human and swine influenza viruses has infected pigs in various countries. Objectives To investigate the relationship between the H1N1pdm viruses isolated from piggery outbreaks in Australia and human samples associated with one of the outbreaks by phylogenetic analysis, and to determine whether there was any reassortment event occurring during the human‐pig interspecies transmission. Methods Real‐time RT‐PCR and full genome sequencing were carried out on RNA isolated from nasal swabs and/or virus cultures. Phylogenetic analysis was performed using the Geneious package. Results The influenza H1N1pdm outbreaks were detected in three pig farms located in three different states in Australia. Further analysis of the Queensland outbreak led to the identification of two distinct virus strains in the pigs. Two staff working in the same piggery were also infected with the same two strains found in the pigs. Full genome sequence analysis on the viruses isolated from pigs and humans did not identify any reassortment of these H1N1pdm viruses with seasonal or avian influenza A viruses. Conclusions This is the first report of swine infected with influenza in Australia and marked the end of the influenza‐free era for the Australian swine industry. Although no reassortment was detected in these cases, the ability of these viruses to cross between pigs and humans highlights the importance of monitoring swine for novel influenza infections.     

Experimental inoculation of pigs with pandemic H1N1 2009 virus and HI cross-reactivity with contemporary swine influenza virus antisera

Please cite this paper as: Vincent et al. (2010) Experimental inoculation of pigs with pandemic H1N1 2009 virus and HI cross-reactivity with contemporary swine influenza virus antisera. Influenza and Other Respiratory Viruses 4(2), 53–60 Background A novel A/H1N1 was identified in the human population in North America in April 2009. The gene constellation of the virus was a combination from swine influenza A viruses (SIV) of North American and Eurasian lineages that had never before been identified in swine or other species. Objectives The objectives were to (i) evaluate the clinical response of swine following experimental inoculation with pandemic H1N1 2009; (ii) assess serologic cross-reactivity between H1N1 2009 and contemporary SIV antisera; and (iii) develop a molecular assay to differentiate North American-lineage SIV from H1N1 2009. Methods Experiment 1: Weaned pigs were experimentally infected with A/California/04/2009 (H1N1). Experiment 2: The cross-reactivity of a panel of US SIV H1N1 or H1N2 antisera with three isolates of pandemic A/H1N1 was evaluated. Experiment 3: A polymerase chain reaction (PCR)-based diagnostic test was developed and validated on samples from experimentally infected pigs. Results and Conclusions In experiment 1, all inoculated pigs demonstrated clinical signs and lesions similar to those induced by endemic SIV. Viable virus and antigen were only detected in the respiratory tract. In experiment 2, serologic cross-reactivity was limited against H1N1 2009 isolates, notably among virus antisera from the same HA phylogenetic cluster. The limited cross-reactivity suggests North American pigs may not be fully protected against H1N1 2009 from previous exposure or vaccination and novel tests are needed to rapidly diagnose the introduction of H1N1 2009. In experiment 3, an RT–PCR test that discriminates between H1N1 2009 and endemic North American SIV was developed and validated on clinical samples.     

Transmission of pandemic influenza H1N1 (2009) in Vietnamese swine in 2009-2010

Please cite this paper as: Trevennec et al. (2012) Transmission of pandemic influenza H1N1 (2009) in Vietnamese swine in 2009–2010. Influenza and Other Respiratory Viruses 6(5), 348–357. Background The pandemic of 2009 was caused by an H1N1 (H1N1pdm) virus of swine origin. This pandemic virus has repeatedly infected swine through reverse zoonosis, although the extent of such infection in swine remains unclear. Objective This study targets small and commercial pig producers in North Vietnam, in order to estimate the extent of H1N1pdm infection in swine and to identify the risk factors of infection. Methods Virologic and serologic surveillance of swine was carried out in 2009–2010 in pig farms (38 swabs and 1732 sera) and at a pig slaughterhouse (710 swabs and 459 sera) in North Vietnam. The sera were screened using a influenza type A‐reactive ELISA assay, and positive sera were tested using hemagglutination inhibition tests for antibody to a panel of H1‐subtype viruses representing pandemic (H1N1) 2009 (H1N1pdm), triple reassortant (TRIG), classical swine (CS), and Eurasian avian‐like (EA) swine lineages. Farm‐level risk factors were identified using a zero‐inflated negative binomial model. Results We found a maximal seroprevalence of H1N1pdm of 55·6% [95% CI: 38·1–72·1] in the slaughterhouse at the end of December 2009, 2 weeks after the peak of reported human fatalities with H1N1pdm. Farm‐level seroprevalence was 29% [95% CI: 23·2–35·7]. In seropositive farms, within‐herd seroprevalence ranged from 10 to 100%. We identified an increased risk of infection for farms that specialized in fattening and a decreased risk of infection in farms hiring external swine workers. Conclusions Our findings suggest extensive reverse‐zoonotic transmission from humans to pigs with subsequent onward transmission within pig herds.     

A novel electrochemical device to differentiate pandemic (H1N1) 2009 from seasonal influenza

Please cite this paper as: Straight et al. (2010) A novel electrochemical device to differentiate pandemic (H1N1) 2009 from seasonal influenza. Influenza and Other Respiratory Viruses 4(2), 73–79. Background One of the challenges of the recent pandemic (H1N1) 2009 influenza outbreak was to differentiate the virus from seasonal influenza when confronting clinical cases. The determination of the virus has implications on treatment choice, and obvious epidemiologic significance. Objectives We set out to apply a novel electrochemical device to samples derived from clinical cases of pandemic (H1N1) 2009 influenza to examine the ability of the device to differentiate these samples from cases of seasonal influenza. Patients/Methods An IRB approved protocol allowed for the use of original nasal wash samples from 24 confirmed human cases pandemic (H1N1) 2009 influenza. Clinical samples from cases of seasonal influenza (Influenza A/H1N1, A/H3N2, and B) were included as controls. Nucleic acids were extracted and samples examined by the ElectraSense^® Influenza A assay (CombiMatrix, Inc). Samples were also examined by RT-PCR or Luminex assays as a comparator. Results and Conclusions The ElectraSense^® Influenza A assay correctly identified 23 of 24 samples of laboratory-confirmed pandemic (H1N1) 2009 Influenza. The assay correctly identified all samples of influenza A/H1N1 and A/H3N2, and differentiated these from pandemic (H1N1) 2009 Influenza in all cases. The ElectraSense^® Influenza A assay proved to be a useful assay to quickly and accurately differentiate pandemic (H1N1) 2009 influenza from seasonal influenza.     

Diversity of influenza viruses in swine and the emergence of a novel human pandemic influenza A (H1N1)

Abstract The novel H1N1 influenza virus that emerged in humans in Mexico in early 2009 and transmitted efficiently in the human population with global spread has been declared a pandemic strain. Here we review influenza infections in swine since 1918 and the introduction of different avian and human influenza virus genes into swine influenza viruses of North America and Eurasia. These introductions often result in viruses of increased fitness for pigs that occasionally transmit to humans. The novel virus affecting humans is derived from a North American swine influenza virus that has acquired two gene segments [Neuraminidase (NA) and Matrix (M)] from the European swine lineages. This reassortant appears to have increased fitness in humans. The potential for increased virulence in humans and of further reassortment between the novel H1N1 influenza virus and oseltamivir resistant seasonal H1N1 or with highly pathogenic H5N1 influenza stresses the need for urgent pandemic planning.     

Epidemiological aspects of pandemic influenza A(H1N1) virus from 2009 to 2011 in Iran

Please cite this paper as: Yavarian et al. (2012). Epidemiological aspects of pandemic influenza A(H1N1) virus from 2009 to 2011 in Iran. Influenza and Other Respiratory Viruses 6(601), e74–e76.     

Original Article: A primary school outbreak of pandemic 2009 influenza A (H1N1) in China

Please cite this paper as: Huai et al. (2010) A primary school outbreak of pandemic 2009 influenza A (H1N1) in China. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2010.00150.x. Background  We investigated the first known outbreak of pandemic 2009 influenza A (H1N1) at a primary school in China. Objectives  To describe epidemiologic findings, identify risk factors associated with 2009 H1N1 illness, and inform national policy including school outbreak control and surveillance strategies. Methods  We conducted retrospective case finding by reviewing the school’s absentee log and retrieving medical records. Enhanced surveillance was implemented by requiring physicians to report any influenza‐like illness (ILI) cases to public health authorities. A case–control study was conducted to detect potential risk factors for 2009 H1N1 illness. A questionnaire was administered to 50 confirmed cases and 197 age‐, gender‐, and location‐matched controls randomly selected from student and population registries. Results  The attack rate was 4% (50/1314), and children from all grades were affected. When compared with controls, confirmed cases were more likely to have been exposed to persons with respiratory illness either in the home or classroom within 7 days of symptom onset (OR, 4·5, 95% CI: 1·9–10·7). No cases reported travel or contact with persons who had traveled outside of the country. Conclusions  Findings in this outbreak investigation, including risk of illness associated with contacting persons with respiratory illness, are consistent with those reported by others for seasonal influenza and 2009 H1N1 outbreaks in school. The outbreak confirmed that community‐level transmission of 2009 H1N1 virus was occurring in China and helped lead to changes in the national pandemic policy from containment to mitigation.