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.     

Oseltamivir-resistant influenza A(H1N1)pdm09 virus in southern Brazil

The neuraminidase (NA) genes of A(H1N1)pdm09 influenza virus isolates from 306 infected patients were analysed. The circulation of oseltamivir-resistant viruses in Brazil has not been reported previously. Clinical samples were collected in the state of Rio Grande do Sul (RS) from 2009-2011 and two NA inhibitor-resistant mutants were identified, one in 2009 (H275Y) and the other in 2011 (S247N). This study revealed a low prevalence of resistant viruses (0.8%) with no spread of the resistant mutants throughout RS.     

新的猪源性甲型H1N1流感病毒

2009年3月在美国和墨西哥流感样患者的呼吸道标本中鉴定出新的猪源性甲型H1N1流感病毒。该病毒可人一人传播,已蔓延到172个国家和地区。现就猪源性甲型H1N1流感病毒的鉴定、基因组结构特征做一综述。     

21世纪的首次大流行：2009甲型（H1N1）流感

2009年4月初,在墨西哥和美国出现一种新型甲型（H1N1）流感病毒。该病毒通过人-人传播迅速在全球范围蔓延。该病毒拥有来自人流感病毒、禽流感病毒和猪流感病毒的基因片段,其HA基因与引发1918年大流行的流感病毒株的HA基因同源性很高。该病毒倾向于感染儿童、青少年、孕妇,以及具有心肺疾病的人。据观察,它在人群中的传播能力高于季节性流感。部分感染患者具有在季节性流感中罕见的呕吐和腹泻症状。先前的流感病毒大流行和2009年爆发的甲型H1N1流感病毒大流行表明,由于流感病毒变异速度快、容易发生基因重排,新产生的变异毒株很可能造成新的大流行,威胁人类健康。由于禽流感病毒和人流感病毒都能感染猪,猪被认为是通过基因重排生成新的大流行病毒的＂混合容器＂。     

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。     

Pandemic swine influenza virus (H1N1): A threatening evolution

“Survival of the fittest” is an old axiom laid down by the great evolutionist Charles Darwin and microorganisms seem to have exploited this statement to a great extent. The ability of viruses to adapt themselves to the changing environment has made it possible to inhabit itself in this vast world for the past millions of years. Experts are well versed with the fact that influenza viruses have the capability to trade genetic components from one to the other within animal and human population. In mid April 2009, the Centers for Disease Control and Prevention and the World Health Organization had recognized a dramatic increase in number of influenza cases. These current 2009 infections were found to be caused by a new strain of influenza type A H1N1 virus which is a re-assortment of several strains of influenza viruses commonly infecting human, avian, and swine population. This evolution is quite dependent on swine population which acts as a main reservoir for the reassortment event in virus. With the current rate of progress and the efforts of heath authorities worldwide, we have still not lost the race against fighting this virus. This article gives an insight to the probable source of origin and the evolutionary progress it has gone through that makes it a potential threat in the future, the current scenario and the possible measures that may be explored to further strengthen the war against pandemic.     

2015年湖南部分地区H9N2亚型流感病毒HA和NA基因遗传进化

我国湖南地区因水禽家禽饲养较多且密集,是流感病毒高发省份。为了监测流感病毒的变异情况,采用RT-PCR技术扩增了10株H9N2亚型流感病毒的HA和NA基因,并进行了序列测定和分析。结果显示,10株分离株均属于欧亚分支中的Y280亚系;HA碱性裂解位点序列均为RSSR↓GLT,为低致病性流感病毒特征;HA受体结合位点234位均为L,具有与人唾液酸α-2,6受体结合的特性;NA蛋白均在颈部 (63–65位) 出现氨基酸缺失,这种缺失能增加流感病毒在哺乳动物中的复制能力。提示H9N2亚型毒株近年有毒力和致病力趋于转强的可能性,因此,要加强对H9N2亚型禽流感病毒的监测,密切关注它的重组趋势。     

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。     

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.     

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.     

53例重症甲型H1N1流感临床分析

目的了解重症甲型H1N1流感的临床特点,探索其治疗方法。方法回顾性分析53例重症甲型H1N1流感患者的临床资料,总结其临床规律及特点。结果重症甲型H1N1流感好发于20～40岁,20例（37.74%）伴有各种基础疾病。51例（96.23%）有发热,且48例（90.57%）为首发症状,多伴随有畏寒、咳嗽、咳痰、乏力、胸闷和气急等症状。发病早期血常规检查白细胞及中性粒细胞多正常或下降;胸部影像学检查提示33例（62.26%）患者继发不同程度的支气管炎或肺炎。患者经奥司他韦或帕拉米韦抗病毒治疗及相应的抗感染、针对基础疾病治疗等,除2例患者自动出院外,余均痊愈出院。结论重症甲型H1N1流感起病急,早诊断、早期积极合理治疗,能改善预后。     

Genetic comparison of H5N1 influenza A viruses isolated from chickens in Japan and Korea

Outbreaks of highly pathogenic avian influenza (HPAI) caused by H5N1 virus occurred during 2003 to 2004 in Korea and Japan. The H5N1 viruses isolated in both countries were genetically similar at > 99% identity in the nucleotide sequences of all eight RNA segments, indicating that they belong to genotype V and are distinct from HPAI viruses prevalent in southeast Asia that belong to genotype Z. These findings indicate that the H5N1 viruses that caused the HPAI outbreaks in both Korea and Japan were derived from a common ancestor.     

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．     

Molecular findings from influenza A(H1N1)pdm09 detected in patients from a Brazilian equatorial region during the pandemic period

After the World Health Organization officially declared the end of the first pandemic of the XXI century in August 2010, the influenza A(H1N1)pdm09 virus has been disseminated in the human population. In spite of its sustained circulation, very little on phylogenetic data or oseltamivir (OST) resistance is available for the virus in equatorial regions of South America. In order to shed more light on this topic, we analysed the haemagglutinin (HA) and neuraminidase (NA) genes of influenza A(H1N1)pdm09 positive samples collected during the pandemic period in the Pernambuco (PE), a northeastern Brazilian state. Complete HA sequences were compared and amino acid changes were related to clinical outcome. In addition, the H275Y substitution in NA, associated with OST resistance, was investigated by pyrosequencing. Samples from PE were grouped in phylogenetic clades 6 and 7, being clustered together with sequences from South and Southeast Brazil. The D222N/G HA gene mutation, associated with severity, was found in one deceased patient that was pregnant. Additionally, the HA mutation K308E, which appeared in Brazil in 2010 and was only detected worldwide the following year, was identified in samples from hospitalised cases. The resistance marker H275Y was not identified in samples tested. However, broader studies are needed to establish the real frequency of resistance in this Brazilian region.     

Antigenic Drift of the Hemagglutinin from an Influenza A (H1N1) pdm09 Clinical Isolate Increases its Pathogenicity In Vitro

Virologica Sinica - The influenza A (H1N1) pdm09 virus emerged in 2009 and has been continuously circulating in humans for over ten years. Here, we analyzed a clinical influenza A (H1N1)...     

Development and diagnostic application/evaluation of pandemic (H1N1) 2009 influenza virus-specific monoclonal antibodies

We prepared mAb specific to the H1N1 2009 virus (H1N1 2009) to facilitate development of an RDT with enhanced sensitivity and specificity. Among these antibodies, we identified two clones--hybridomas 1H7E1 and 3A3H7-that specifically bound to H1N1 2009 (non-seasonal) and were very suitable for application to a diagnostic kit. The affinity constants (K(a)) of 1H7E1 and 3A3H7 were 1.10 × 10(10) and 2.35 × 10(10), respectively. To identify the antibodies, we performed ELISA and immunoblot analyses and found that 1H7E1 recognized a conformational epitope of HA while 3A3H7 recognized a linear epitope. In clinical evaluations using specimens from 215 patients, a lateral flow rapid testing kit comprising these mAb showed a sensitivity of 81.5% (75/92) and a specificity of 96.7% (119/123). Results using the RDT kit were well correlated with conventional RT-PCR methods as commonly and commercially used. Based on our findings, we believe that use of these mAb with a rapid evaluation kit could serve as a good diagnostic tool for H1N1 2009.     

Phylogenetic analyses of pandemic influenza A (H1N1) virus in university students at Tobetsu, Hokkaido, Japan

Pandemic influenza H1N1 virus (A[H1N1]pdm09) emerged in 2009. To determine the phylogeography of A(H1N1)pdm09 in a single population, 70 strains of the virus were isolated from university students or trainee doctors at Tobetsu, Hokkaido, Japan, between September and December 2009. The nucleotide sequences of the HA1 region of the HA genes and described phylogenetic relationships of the strains circulating among them were analyzed. It was found that the 70 isolates could be phylogenetically separated into three groups and that two epidemics were caused by different groups of the virus. The three groups were also distinguishable from each other by three amino acid changes: A197T, S203T and Q293H. The substitution of S203T, which is located in the antigenic site, suggests antigenic drift of the virus.     

Diagnosis of influenza viruses with special reference to novel H1N1 2009 influenza virus

On 15 April and 17 April 2009, novel swineorigin influenza A (H1N1) virus was identifi ed in specimens obtained from two epidemiologically unlinked patients in the United States. The ongoing outbreak of novel H1N1 2009 influenza (swine influenza) has caused more than 3,99,232 laboratory confi rmed cases of pandemic influenza H1N1 and over 4735 deaths globally. This novel 2009 influenza virus designated as H1N1 A/swine/California/04/2009 virus is not zoonotic swine flu and is transmitted from person to person and has higher transmissibility then that of seasonal influenza viruses. In India the novel H1N1 virus infection has been reported from all over the country. A total of 68,919 samples from clinically suspected persons have been tested for influenza A H1N1 across the country and 13,330 (18.9%) of them have been found positive with 427 deaths. At the All India Institute of Medical Sciences, New Delhi India, we tested 1096 clinical samples for the presence of novel H1N1 influenza virus and seasonal influenza viruses. Of these 1096 samples, 194 samples (17.7%) were positive for novel H1N1 influenza virus and 197 samples (18%) were positive for seasonal influenza viruses. During outbreaks of emerging infectious diseases accurate and rapid diagnosis is critical for minimizing further spread through timely implementation of appropriate vaccines and antiviral treatment. Since the symptoms of novel H1N1 influenza infection are not specifi c, laboratory confi rmation of suspected cases is of prime importance.