H5N1亚型禽流感病毒聚合酶酸性蛋白真核表达载体的构建与表达

目的构建甲型禽流感病毒H5N1亚型聚合酶酸性蛋白(PA)的真核表达载体,并表达其编码蛋白PA。方法采用RT-PCR法扩增PA基因,克隆至pMD18-T载体中构pMD18-T-PA质粒。双酶切pMD18-T-PA质粒与pXJ40-HA质粒后,胶回收并连接目的片段,构建真核表达载体pXJ40-HA-PA,鉴定后转染293T细胞。采用免疫印迹法(Western blot)鉴定重组PA蛋白的表达。结果成功构建了禽流感病毒H5N1亚型PA基因的真核表达载体,并在真核细胞中成功表达出分子量为75kD的重组蛋白。结论成功构建禽流感病毒H5N1亚型PA基因的真核表达载体,为后期进一步研究PA蛋白的功能奠定了基础。     

H7N9亚型禽流感病毒核蛋白NP原核表达载体的构建与表达

目的构建甲型H7N9禽流感病毒NP基因的原核表达载体,并表达其编码重组蛋白。方法 RT-PCR法扩增H7N9病毒NP基因,克隆至原核表达载体PET28a(+)中,构建表达载体PET28a(+)-NP质粒;经PCR、双酶切、测序鉴定后,将PET28a(+)-NP质粒转化表达菌BL21(DE3),用IPTG诱导表达NP重组蛋白。应用western blot法鉴定NP蛋白的表达。结果成功构建NP基因的原核表达载体,在大肠杆菌中表达出分子量为56kD的NP重组蛋白。结论实现了禽流感病毒H7N9NP重组蛋白在原核系统中的高效表达,为禽流感诊断试剂及单抗的研发工作奠定了基础。     

WHO确认的人感染H5N1亚型禽流感病毒病例的流行病学分析报告

中国香港特别行政区在1997年首次报告人感染H5N1亚型禽流感病毒疫情,共有18例病例,其中6例死亡。当时香港有农场及活禽市场爆发了禽间高致病性禽流感疫情,在采取了快速扑杀全港鸡只的措施后,人间病例再没有出现。2003年2月,来自同一香港家庭的2名成员(其中1名死亡)被证实为人禽     

广西禽流感H5N1亚型病毒HA基因序列分析

目的了解广西禽流感H5N1亚型病毒的基因特性.方法2011年在广西农贸市场采集污水、笼具涂抹、粪便标本,经H5亚型特异实时荧光定量PCR方法(Real-time fluorescence quantitative RT-PCR)检测,阳性样本进行病毒血凝素(hemagglutinin,HA)基因扩增后对产物直接测序,测序结果与已知参考毒株进行序列比对及系统进化分析.结果对阳性样本病毒HA基因测序获得6份HA序列,均分布在进化分支2.3.2的Ⅱ-1分支下.广西的6序列无论是氨基酸还是核苷酸的都是高度同源的,其核苷酸同源性在99.5%~100%,氨基酸同源性在99.5%~99.8%;序列测定的结果同时表明无论是受体特异性还是连接肽都是禽源的.结论2011年广西农贸市场流行的禽流感H5N1亚型病毒主要以进化分支2.3.2Ⅱ-1为主,均为禽源性的病毒.     

华东地区高致病性H5N6禽流感病毒血凝素蛋白分子特征分析

目的分析2017年以来中国华东地区高致病性H5N6禽流感病毒的HA基因分子特征。方法 H5N6核酸阳性标本采用9～11日龄鸡胚进行病毒分离,病毒基因测序采用下一代测序技术,相关的参考序列下载自GISAID或NCBI网站,序列比对和进化树构建采用ClustalX、Blasts及Mega 6.1等生物信息学软件。结果 2017年以来,在江苏省活禽市场和禽流感患者的标本中,成功分离出43株H5N6禽流感病毒,对33株病毒进行了基因组测序。选择其中的27株H5N6病毒的HA基因进行分子进化分析,clade 2.3.4.4h有20株,clade 2.3.4.4e有3株,另外4株归类于clade 2.3.4.4b;多个碱性氨基酸出现在病毒HA蛋白的裂解位点,是高致病性禽流感病毒的典型分子特征;HA蛋白受体结合位点的222和224位氨基酸分别是Q和G,具有结合禽类受体α2-3半乳糖苷唾液酸(SAα2-3Gal)的特性,158位点糖基化位点丢失,但新的糖基化位点出现在124位点上。结论 2017年HA基因clade 2.3.4.4h是我国华东地区H5N6病毒优势基因型,病毒处于持续动态进化中,需要继续对病毒进化进行监测。     

甲型流感病毒H1N1亚型NS1蛋白真核表达载体的构建与表达

[目的]构建甲型流感病毒H1N1亚型NS1蛋白真核表达载体,并在293T细胞中表达.[方法]采用RT-PCR技术,从甲型流感病毒H1N1毒株提取的病毒总RNA中,扩增NS1全长基因,将其克隆至pMD18-T Vector中构建pMD18-T-NS1质粒,双酶切pMD18-T-NS1与PXJ40-HA后,构建真核表达载体PXJ40-HA-NS1,经酶切及测序鉴定后将质粒转染到293T细胞中,通过免疫印迹法鉴定NS1蛋白的表达.[结果]酶切、测序证明重组真核表达载体PXJ40-HA-NS1构建成功,免疫印迹法可见NS1基因编码蛋白表达.[结论]成功构建甲型流感病毒H1N1亚型NS1蛋白真核表达载体PXJ40-HA-NS1,并在293T细胞中传染表达,该表达载体的构建为后期建立稳定表达NS1蛋白的细胞模型和NS1蛋白功能研究提供了材料.     

职业暴露人群人感染高致病性禽流感H5N1风险研究进展

当前,全球高致病性禽流感[PHAI(H5N1)]疫情形式仍十分严峻,人间HPAI(H5N1)疫情风险将持续存在,从事禽类养殖及活禽市场交易工作的人员是HPAI(H5N1)禽流感病毒感染的高危人群。以发生疫情后的应急应对模式难以应对当前和未来不断增大的疫情风险挑战。开展职业暴露人群人感染PHAI(H5N1)风险管理,在减少人感染病例的发生显得更为重要。本课题组在查阅分析相关文献基础上,归纳职业暴露中人感染HPAI(H5N1)的风险因子及风险评估方法,为加强职业暴露人群人感染HPAI(H5N1)风险管理提供参考。     

云南省边境地区禽流感H5N1亚型病毒遗传多样性分析

目的 了解云南省边境地区禽流感H5N1亚型病毒遗传多样性.方法 2009-2011年7月在云南省边境地区采集境外家禽和野生鸟类棉拭子样品,经H5/Nl亚型特异性多重RT-PCR检测,阳性样品进行病毒HA基因扩增,克隆至pMD 18-T载体测序,并与已知参考毒株进行序列比对及系统发育分析.结果 36份阳性样品病毒HA基因测序获得15种HA序列,存在2个不同进化分支(2.3.2、2.3.4),2.3.2进一步可划分为3个进化小分支(Ⅱ-1～Ⅱ-3),2.3.4进一步可划分为2个进化小分支(Ⅰ-1和Ⅰ-2).2.3.2Ⅱ-1、Ⅱ-2毒株是新出现的H5N1亚型病毒变异株.结论 2009- 2011年7月云南省边境地区H5N1亚型病毒具有遗传多样性,病毒经历了多分支(2.3.2、2.3.4)至单一支(2.3.2)的进化过程.     

禽流感病毒H5N1抗原基因克隆及体外转录

目的通过基因克隆和体外转录,获得H5N1禽流感病毒抗原基因的RNA全长片段,为病原学检测提供阳性定量标准品。方法设计H5N1禽流感病毒血凝素(HA)、神经氨酸酶(NA)及基质蛋白M(M)的基因克隆引物,RT-PCR从病毒RNA获得相应片段,分别连接至pGEM-T Easy质粒并筛选阳性重组质粒,测序鉴定后酶切线性化,用T7 RNA聚合酶进行体外转录,产物用DNase酶处理、纯化后测定浓度,RT-PCR验证。结果获得含H5N1禽流感病毒HA、NA、M全长基因序列的RNA片段,并可准确定量其拷贝数,质量浓度HA为503.9 ng/μL、NA为379.2 ng/μL、M为437.8 ng/μL。结论获得的RNA片段可作为H5N1禽流感病毒核酸快速检测方法的阳性定量标准品。     

高致病性H5N1禽流感全球分布地理信息系统时空分析

目的 了解高致病性H5N1禽流感疫情的时间与空间分布,为研究病毒的传播途径与机制提供假设和间接证据,为疾病的预防和预警提供技术支持。方法 收集2003年3月—2012年3月世界卫生组织和世界动物卫生组织报告中官方确认的5 963起暴发事件,运用多距离空间聚类分析、空间自相关等基于地理信息系统（GIS）的分析手段对高致病性H5N1禽流感的全球分布进行时间和空间尺度分析。结果 2003—2012年共标记5 963个高致病性H5N1禽流感暴发点,亚洲、欧洲、非洲暴发点分别为3 647、1 309、1 007个,分别占61.16%、21.95%、16.89%;亚洲国家越南暴发点数（1 055个）和暴发率（2.22/百万头）最高,欧洲国家暴发点数最多的为德国（407个）,暴发率最高的为罗马尼亚（1.09/百万头）,非洲国家埃及暴发点数（758个）和暴发率（1.35/百万头）最高;空间自相关函数（Moran’s I）和多距离空间聚类分析结果表明,2003年3月—2006年3月实际K值在0~5 000 km尺度范围内大于期望K值（Moran’s I=0.19,P<0.05）,2006年4月—2009年7月实际K值在0~4 500 km尺度范围内大于期望K值（Moran’s I=0.02,P>0.05）,2009年8月—2012年3月实际K值在0~6 000 km尺度范围内大于期望K值（Moran’s I=0.10,P<0.01）,其分布特征随着时间和空间尺度的变化而改变。结论 高致病性H5N1禽流感的时空分布存在显著异质性,其空间分布模式对疫情预警有重要意义,人类活动、候鸟迁徙可能是禽流感传播的主要途径。     

Experimental infection of cattle with highly pathogenic avian influenza virus (H5N1)

Four calves were experimentally inoculated with highly pathogenic avian influenza virus A/cat/Germany/R606/2006 (H5N1) isolated from a cat in 2006. All calves remained healthy, but several animals shed low amounts of virus, detected by inoculation of nasal swab fluid into embryonated chicken eggs and onto MDCK cells. All calves seroconverted.     

高致病性禽流感H5N1病毒M1蛋白的重组表达及在感染检测中的初步应用

目的:原核表达重组高致病性禽流感基质蛋白M1并分析其在感染检测中的作用。方法:根据NCBI公布的基质蛋白M1的核苷酸序列设计特异性引物,用高致病禽流感H5N1病人分离的病毒提取病毒RNA进行反转录合成cD-NA,扩增基质蛋白M1基因。将M1基因克隆到pQE30原核表达载体进行非融合表达,纯化重组表达的蛋白并用免疫学方法检测分析。结果:克隆了高致病禽流感H5N1病毒基质蛋白M1基因,并采用pQE30原核表达载体成功表达该蛋白。以该重组蛋白为检测包被抗原建立间接ELISA,检测6份病人血清标本均为阳性,而正常对照人群为阴性。结论:高致病禽流感H5N1病毒M1蛋白可以应用于感染检测中。     

Emergence of novel clade 2.3.4 influenza A (H5N1) virus subgroups in Yunnan Province,China

From December 2013 to March 2014, a major wave of highly pathogenic avian influenza outbreak occurred in poultry in Yunnan Province, China. We isolated and characterized eight highly pathogenic avian influenza A (H5N1) viruses from poultry. Full genome influenza sequences and analyses have been performed.Sequence analyses revealed that they belonged to clade 2.3.4 but did not fit within the three defined subclades. The isolated viruses were provisional subclade 2.3.4.4e. The provisional subclade 2.3.4.4e viruses with six internal genes from avian influenza A (H5N2) viruses in 2013 were the novel reassortant influenza A (H5N1) viruses which were associated with the outbreak of H5N1 occurred in egg chicken farms in Yunnan Province. The HA genes were similar to subtype H5 viruses isolated from January to March of 2014 in Asia including H5N6 and H5N8. The NA genes were most closely related to A/chicken/Vietnam/NCVD-KA423/2013 (H5N1) from the subclade 2.3.2. The HI assay demonstrated a lack of antigenic relatedness between clades 2.3.4.4e and 2.3.4.1 (RE-5 vaccine strain) or 2.3.2.2 (RE-6 vaccine strain).     

Highly pathogenic avian influenza virus (H5N1) in domestic poultry and relationship with migratory birds, South Korea

During the 2006-2007 winter season in South Korea, several outbreaks of highly pathogenic avian influenza virus (H5N1) were confirmed among domestic poultry and in migratory bird habitats. Phylogenetic analysis showed that all isolates were closely related and that all belong to the A/bar-headed goose/Qinghai/5/2005-like lineage rather than the A/chicken/Korea/ES/2003-like lineage.     

Replacement of sublineages of avian influenza (H5N1) by reassortments, sub-Saharan Africa

Eight new full-length sequences from highly pathogenic avian influenza viruses (H5N1) from 4 states in southwest Nigeria were analyzed. All gene sequences were more closely related to the first strains found in Nigeria in 2006 than to any strain found outside the country. Six viruses had evolved by at least 3 reassortment events (AC HA/NS, AC NS) from previously identified sublineages A (EMA 2) and C (EMA 1). Our results suggest that highly pathogenic avian influenza viruses (H5N1) initially imported into Nigeria in 2006 have been gradually replaced by various reassortments. In all reassortants, nonstructural genes were derived from sublineage C with 2 characteristic amino acids (compared with sublineage A). If the high prevalence of reassortants was typical for West Africa in 2007, the absence of such reassortants anywhere else suggests that reintroductions of influenza A (H5N1) from Africa into Eurasia must be rare.     

Safety,immunogenicity and efficacy of poxvirus-based vector vaccines expressing the haemagglutinin gene of a highly pathogenic H5N1 avian influenza virus in pigs

This study investigates the safety, immunogenicity and efficacy of different pox-vector vaccines expressing the haemagglutinin of a highly pathogenic (HP) H5N1 avian influenza virus (AIV) (A/chicken/Indonesia/7/03) in pigs. Pigs were vaccinated twice, with a 4-week interval, with a fowlpox (TROVAC^®), a canarypox (ALVAC^®), or a vaccinia (NYVAC) vector vaccine combined with an oil-in-water adjuvant, with the unadjuvanted NYVAC, or left unvaccinated. Six weeks after the second vaccination, all pigs were challenged intra-tracheally with low pathogenic (LP) H5N2 AIV A/chicken/Belgium/150/99. Sera were examined in haemagglutination inhibition (HI) tests against the H5N1 AIV from which the vaccine haemagglutinin derived, the challenge virus and the human A/Vietnam/1194/04 HPAIV. After challenge pigs were compared for H5N2 virus replication in the trachea and 4 lung lobes at 24 or 72 h post-challenge. Vaccination was well tolerated by all animals. Antibody titres peaked 2 weeks after the second vaccination and were 2- to 4-fold higher against the vaccine virus than heterologous H5 viruses. The NYVAC and ALVAC adjuvanted vaccines consistently induced higher antibody titres than TROVAC or NYVAC without adjuvant. Following challenge, the H5N2 challenge virus was isolated from all unvaccinated pigs, while 19 out of 21 vaccinates showed complete virological protection. Pox-vector vaccines were safe, immunogenic and efficacious against challenge with a heterologous H5 AIV, offering an alternative to classical inactivated vaccines. It remains to be seen whether they would protect against a swine-adapted H5 virus, which may replicate 100–1000 times better than our challenge virus.     

Reassortant avian influenza virus (H5N1) in poultry, Nigeria, 2007

Genetic characterization of a selection of influenza virus (H5N1) samples, circulating in 8 Nigerian states over a 39-day period in early 2007, indicates that a new reassortant strain is present in 7 of the 8 states. Our study reports an entirely different influenza virus (H5N1) reassortant becoming predominant and widespread in poultry.     

Susceptibility of North American ducks and gulls to H5N1 highly pathogenic avian influenza viruses

Since 2002, H5N1 highly pathogenic avian influenza (HPA1) viruses have been associated with deaths in numerous wild avian species throughout Eurasia. We assessed the clinical response and extent and duration of viral shedding in 5 species of North American ducks and laughing gulls (Larus atricilla) after intranasal challenge with 2 Asian H5N1 HPAI viruses. Birds were challenged at approximately equal to 10 to 16 weeks of age, consistent with temporal peaks in virus prevalence and fall migration. All species were infected, but only wood ducks (Aix sponsa) and laughing gulls exhibited illness or died. Viral titers were higher in oropharyngeal swabs than in cloacal swabs. Duration of viral shedding (1-10 days) increased with severity of clinical disease. Both the hemagglutination-inhibition (HI) and agar gel precipitin (AGP) tests were able to detect postinoculation antibodies in surviving wood ducks and laughing gulls; the HI test was more sensitive than the AGP in the remaining 4 species.