新型甲型H7N9禽流感病毒实验室检测及防控策略

2013年3月中国报道了首例因感染新型甲型H7N9流感病毒而致死的病例,引发疫情的H7N9禽流感病毒是一种鸟类的禽流感病毒毒株基因重配的新型病毒,该病毒是首次从人群中发现的一种新型H7N9亚型禽流感病毒,也是全球首次发现的新亚型流感病毒。禽流感是一种新亚型、起病急、进展快、致死率高等为特点的急性传染病,新型H7N9病毒最显著的特征之一是在家禽中无明显致病性,却能感染人类并引起较高的病死率。可以预见这种新型H7N9亚型禽流感还将会持续并引起严重的公共卫生问题,必须对此加以高度重视,建立健全防控体系建设和联动机制,加强健康教育工作,从而最大限度地减少禽流感对人类健康和生命的危害。本文对该病毒的病原学特点及实验室检测方法及防控策略进行简要综述。     

北京顺义区人感染H7N9禽流感风险监测与防控

目的评估北京市顺义区人感染H7N9禽流感发生风险,为完善H7N9禽流感防控策略提供科学依据。方法2013年4-12月,对北京市首例人感染H7N9禽流感病例感染来源进行调查,采集顺义区普通人群、禽类职业人群、流感样病例、肺炎病例咽拭子标本及禽类饲养、屠宰环境和公园野禽粪便标本进行H7N9禽流感病毒核酸检测,分析感染情况。结果北京市首例人感染H7N9禽流感病例病家外环境、禽类运输车、鸡笼涂抹标本均检测出H7N9禽流感病毒核酸,而病例本村其他户散养禽类及其环境、本村周边野禽标本均未检出H7N9禽流感病毒核酸;咽拭子标本普通人群440件、禽类职业人群829件、流感样病例1 053件、肺炎病例109件,禽类饲养及屠宰环境涂抹173件,野禽粪便376件,均未检出H7N9禽流感病毒核酸。结论顺义区人群及本地禽间及环境中均未发现H7N9禽流感病毒,输入性活禽交易及宰杀是顺义区人群感染H7N9禽流感的主要风险来源。相关部门应严格落实取缔活禽贩卖宰杀及加强禽间、人群H7N9病毒感染监测等防控措施。     

2014-2015年株洲市禽类职业暴露人群及外环境禽流感病毒监测分析

目的 了解株洲市职业暴露人群禽流感病毒的感染状况和外环境禽流感病毒分布情况,为防控人禽流感提供科学依据。 方法 采用红细胞凝集抑制试验检测2014-2015年株洲市200名禽类职业暴露人群血清禽流感病毒H5N1和H7N9血凝素抗体,荧光定量PCR法检测630份禽类市场外环境标本禽流感病毒A型及H5、H7、H9亚型病毒核酸。 结果 200名职业人群中除1人为H5N1抗体阳性外,其余均为H5N1/H7N9抗体阴性,H5N1抗体阳性率为0.5%;630份外环境标本A型禽流感病毒核酸阳性率为52.70%,病毒亚型以H5和H9亚型为主。不同类型标本中均检出阳性标本,以清洗禽类污水阳性率较高为69.54%(χ²=66.33,P<0.05),且冬春季检出率高于夏秋季(χ²=7.15,P<0.05)。 结论 2014-2015年株洲市禽类市场存在H5、H7、H9禽流感病毒,提示接触禽类、禽类市场暴露有人感染禽流感的风险,应加强人及外环境禽流感监测,落实检疫准入,强化市场监管、消毒、休市等综合性防控措施。     

人感染禽流感家庭聚集性病例研究进展

1997年以来,全球多个国家相继出现人感染H5N1禽流感家庭聚集性病例,随后中国局部地区也陆续报告了人感染H7N9禽流感相关病例。目前存在的人传人的现象是有限非持续的,具体的人际间传播途径与方式并不清楚且尚无证据证实上述2种病毒可以在人间持续传播。家庭聚集性病例多发生在与禽类接近或接触的人群中,可能存在的遗传易感性以及个体间受体表达的差异增加了家庭成员感染禽流感病毒的风险。随着人感染H5N1与H7N9禽流感病毒的持续流行以及病毒自身变异的发生,不排除其获得对人类的适应性突变可能性。人感染H7N9病例中未检测出的症状轻微感染者可能会引起更难以控制的人际间流行。本文将从人感染H5N1、H7N9病毒家庭聚集性病例的流行病学特征、传播模式以及传播能力等方面进行系统阐述,为今后禽流感疫情的防控提供一定的科学依据。     

人感染禽流感流行现状及疫苗研究进展

禽流感病毒(Avian Influenza Viruses,AIV)是一种人兽共患传染病的病原体,属于甲型流感病毒.禽流感病毒因其变异快、感染性和致病性强等特点不仅对家禽造成严重危害,对人类健康也构成严重威胁.1997年香港首次出现H5N1禽流感跨种感染人且致人死亡的事件[1],引起了世界各国的高度关注.2013年3月,中国部分城市发现了人感染H7N9禽流感病毒病例,随后出现了暴发疫情[2],引发全球的高度关注.有效防控高致病性禽流感对保障公共卫生安全意义重大.本文对人感染禽流感病毒的流行现状及疫苗的研究进展进行综述.     

长沙市活禽市场人H9N2亚型禽流感感染来源的研究

  目的  探讨人H9N2亚型禽流感病毒(avian influenza virus,AIV)的感染来源。  方法  对2014-2015年长沙市活禽市场环境开展AIV核酸监测,收集全球人感染H9N2 AIV病例数据,利用MEGA 6软件对全球人感染H9N2 AIV、活禽市场环境H9N2 AIV和部分禽H9N2 AIV血凝素(hemagglutinin,HA)、神经氨酸酶(neuraminidase,NA)及非结构蛋白(nonstructural protein,NS)基因进行进化分析。  结果  2014-2015年长沙市活禽市场环境中H9 AIV的核酸阳性率最高(占44.76%),污染较为严重。全球共报告27例人感染H9N2 AIV病例,绝大多数病例经治疗后康复,流行病学调查显示59.26%(16/27)的病例明确有禽类或活禽市场暴露史。HA、NA及NS进化分析显示2013-2016年分离自湖南、广东的人源H9N2 AIV分离株与湖南和广东辖区活禽市场环境中分离到的H9N2 AIV亲缘关系近,核苷酸相似性高达97%~99%。  结论  活禽市场是人H9N2 AIV的感染来源之一。     

把好“手部呼吸食品”卫生关科学防控H7N9禽流感

人感染H7N9禽流感是由H7N9亚型禽流感病毒引起的急性呼吸道传染病。自今年2月以来,上海市、安徽省、江苏省等地先后发生不明原因重症肺炎病例,后发现为感染H7N9龠流感病毒。截至4月5日23时,中国内地人感染H7N9禽流感病例数上升为16例,其中6人死亡。H7N9禽流感疫情随即成为了人们关注的焦点。党中央、国务院领导高度重视,习近平总书记、李克强总理分别作出重要指示和批示,要求做好患者救治和防控工作。国家卫生和计划生育委员会先后印发了《人感染H7N9禽流感诊疗方案（20I3年第1版）》《人感染H7N9禽流感医院感染预防与控制技术指南（2013年版）》《人感染H7N9禽流感疫情防控方案》（第一版）等。本刊就一般人群H7N9龠流感的防控知识作一汇编,以期提高广大读者对H7N9的认识和防护能力。     

嘉兴市外环境禽流感病毒污染状况及职业暴露人群H5N6、H7N9和H9N2抗体水平调查

目的 了解嘉兴市外环境禽流感病毒分布情况及涉禽职业暴露人群禽流感病毒感染现状,为科学有效防控人感染禽流感疫情提供科学依据。 方法 实时荧光定量PCR检测2013年3月-2016年4月采集的嘉兴市3 115份外环境标本的A型流感病毒核酸,并对A型流感病毒核酸阳性的标本进一步进行H5、H7、H9亚型检测。采用马血红细胞凝集抑制试验检测2015年4月和2016年4月采集的嘉兴市140名涉禽职业暴露人群血清中的H5N6、H7N9和H9N2血凝素抗体。 结果 外环境标本中A型流感病毒核酸阳性率为18.11%,H5、H9、H7亚型阳性率分别为0.64%、3.21%、5.07%;同时,外环境标本中检出不同亚型混合污染标本74份,且H9/H7混合污染的阳性率达到1.86%。A型流感病毒及H7亚型阳性率在冬春季节出现高峰,且在城乡活禽市场的阳性率明显高于其他场所;宰杀或摆放禽肉案板表面和清洗禽类的污水标本中A型流感病毒及H7亚型的阳性率明显高于其他标本类型。140份人群血清标本共检出H9N2抗体阳性标本5份,阳性率为3.57%,未检出H5N6、H7N9抗体阳性标本。 结论 2013-2016年嘉兴市外环境中存在H5、H9、H7亚型污染,且涉禽职业暴露人群中少量的H9N2禽流感病毒无症状感染者,提示禽类接触、活禽交易市场暴露有感染禽流感病毒风险,因此应做好重点人群的健康教育及重点区域的禽流感病毒监测,防止人感染禽流感疫情的发生。     

芜湖市首例人感染H7N9流感病例调查报告

目的探讨人感染H7N9流感发病特点及感染来源,为科学防控人感染H7N9流感提供依据。方法通过对人感染H7N9流感病例的发病经过、暴露因素及可能的感染来源进行流行病学调查,采集患者医学观察的密切接触者、职业暴露人群及相关禽和环境标本进行H7N9病毒核酸检测。结果患者有明确的活禽接触史,咽拭子和下呼吸道标本H7N9流感病毒核酸检测阳性,确诊感染人感染H7N9流感。病例所在活禽交易市场鸡咽拭子和环境标本H7N9流感病毒核酸阳性检出率为12.12%。检测密切接触者13人和职业暴露人群8人,H7N9流感病毒核酸均为阴性。76名密切接触者和8名职业暴露人群经医学观察均未发现异常。结论人感染H7N9流感,感染来源可能是农贸市场活禽摊档,未发现人传人情况。     

2011 - 2015年宿迁市禽流感职业暴露人群和环境监测结果分析

摘要:目的 了解宿迁市职业暴露人群H5N1 禽流感病毒抗体水平和环境中禽流感病毒的分布情况,为禽流感防控提供科学依据。方法 在2011 - 2015年采集从事家禽养殖、屠宰等人群血清标本用血凝抑制试验检测H5N1 抗体;对在城乡活禽市场等采集的环境标本用Real-time PCR法检测禽流感病毒FluA、H5、H7、H9核酸。结果 职业暴露人群572人份血清A（H5N1）抗体均为阴性;1 038份环境标本共检出流感A型阳性标本65份,阳性率为6.26%（其中H5阳性率1.64%,H7阳性率0.19%,H9阳性率3.28%,A未分型0.48%,混合感染0.58%）。结论 职业暴露人群血清标本中未检测出A（H5N1）禽流感病毒抗体阳性标本;宿迁市监测点环境中存在H5、H7、H9 禽流感病毒,存在人感染高致病性禽流感的风险。禽流感感染风险主要集中在城乡活禽市场。     

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.     

Recombinant H7 hemagglutinin forms subviral particles that protect mice and ferrets from challenge with H7N9 influenza virus

A novel avian-origin influenza A H7N9 virus emerged in China in 2013 and continues to cause sporadic human infections with mortality rates approaching 35%. Currently there are no approved human vaccines for H7N9 virus. Recombinant approaches including hemagglutinin (HA) and virus-like particles (VLPs) have resulted in experimental vaccines with advantageous safety and manufacturing characteristics. While high immunogenicity of VLP vaccines has been attributed to the native conformation of HA arranged in the regular repeated patterns within virus-like structures, there is limited data regarding molecular organization of HA within recombinant HA vaccine preparations. In this study, the full-length recombinant H7 protein (rH7) of A/Anhui/1/2013 (H7N9) virus was expressed in Sf9 cells. We showed that purified full-length rH7 retained functional ability to agglutinate red blood cells and formed oligomeric pleomorphic subviral particles (SVPs) of ∼20 nm in diameter composed of approximately 10 HA0 molecules. No significant quantities of free monomeric HA0 were observed in rH7 preparation by size exclusion chromatography. Immunogenicity and protective efficacy of rH7 SVPs was confirmed in the mouse and ferret challenge models suggesting that SVPs can be used for vaccination against H7N9 virus.     

Immunologic evaluation of 10 different adjuvants for use in vaccines for chickens against highly pathogenic avian influenza virus

Avian influenza viruses (AIV) are a threat to poultry production worldwide. Vaccination is utilized as a component of control programs for both high pathogenicity (HP) and low pathogenicity (LP) AIV. Over 95% of all AIV vaccine used in poultry are inactivated, adjuvanted products. To identify the best formulations for chickens, vaccines were prepared with beta-propiolactone (BPL) inactivated A/British Columbia/314514-1/2004 H7N3 LP AIV using ten commercially available or experimental adjuvants. Each vaccine formulation was evaluated for immunogenicity in chickens. Challenge studies with an antigenically homologous strain of HPAIV were conducted to compare protection against mortality and measure reductions in virus levels in oral swabs. The four best adjuvants from the studies with BPL inactivated antigen were selected and tested identically, but with vaccines prepared from formalin inactivated virus. Mineral and vegetable oil based adjuvants generally induced the highest antibody titers with 100% seroconversion by 3 weeks post vaccination. Chitosan induced positive antibody titers in 100% of the chickens, but the titers were significantly lower than those of most of the oil based adjuvants. Antibody levels from calcium phosphate and alginate adjuvanted groups were similar to those of non-adjuvanted virus. All groups that received adjuvanted vaccines induced similar levels of protection against mortality (0–20%) except the groups vaccinated with calcium phosphate adjuvanted vaccines, where mortality was similar (70%) to groups that received non-adjuvanted inactivated virus or no vaccine (60–100% mortality). Virus shedding in oral swabs was variable among the treatment groups. Formalin inactivated vaccine induced similar antibody titers and protection against challenge compared to BPL inactivated vaccine groups. These studies support the use of oil adjuvanted vaccines for use in the poultry industry for control for AIV.     

两种流行性感冒病毒裂解疫苗安全性与免疫原性研究

目的：评价国产流行性感冒裂解疫苗的安全性和免疫原性。方法：按整群随机抽样原则,以进口同类疫苗作为对照开展现场临床试验;比较两种疫苗免后不良反应率、抗体阳转率、保护率及几何平均滴度（GMT）。结果：试验组及对照组接种后全身不良反应率分别为2．7％和3．6％（P〉0．05）,局部不良反应率分别为7．2％和9．6％（P〉O．05）;试验疫苗流感病毒HINI、H3N2及B（亚）型的HI抗体总阳转率分别为81．6％,92．4％和78．0％;对照疫苗流感病毒HIN1、H3N2及B（亚）型的HI抗体总阳转率分别为87．1％,88．3％0和80．8％,三（亚）型流感抗体总阳转率差异无统计学意义;三（亚）型流感HI抗体达到保护水平的保护率的比较中,只有婴幼儿试验组和对照组的免后B型HI抗体滴度≥1：40,差异有统计学意义,试验组大于对照组,其余3组差异无统计学意义;三（亚）型流感抗体免后GMT的差异亦无统计学意义。结论：国产流感裂解疫苗全身和局部不良反应与进口同类疫苗无差异,免后抗体阳转率较高,抗体滴度上升幅度较大,具有良好的安全性和免疫原性。     

The immune response of a recombinant fowlpox virus coexpressing the HA gene of the H5N1 highly pathogenic avian influenza virus and chicken interleukin 6 gene in ducks

Ducks have played an important role in the emergence of H5N1 subtype of highly pathogenic avian influenza (HPAI), and the development of an effective vaccine against HPAI in ducks is a top priority. It has been shown that a recombinant fowlpox virus (FPV)-vectored vaccine can provide protection against HPAI in ducks. In this study, a recombinant fowlpox virus (rFPV-AIH5AIL6) coexpressing the haemagglutinin (HA) gene of the H5N1 subtype of the avian influenza virus (AIV) and chicken interleukin 6 gene was constructed and tested in Gaoyou and cherry valley ducks to evaluate the immune response in ducks. These animal studies demonstrated that rFPV-AIH5AIL6 induced a higher anti-AIV HI antibody response, an enhanced lymphocyte proliferation response, an elevated immune protection, and a reduction in virus shedding compared to a recombinant fowlpox virus expressing the HA gene alone (rFPV-SYHA). These data indicate that rFPV-AIH5AIL6 may be a potential vaccine against the H5 subtype of avian influenza in ducks and chicken interleukin 6 may be an effective adjuvant for increasing the immunogenicity of FPV-vectored AIV vaccines in ducks.     

人及禽类禽流感病毒蛋白芯片检测方法建立

目的建立可同时检测人及禽类禽流感病毒的蛋白芯片方法。方法采用醛基化玻璃载体蛋白芯片和双位点模式,将禽流感病毒H1、H3、H5、H7、H9、N1、N2、NP、NS1等9种亚型抗原以最佳浓度,点样于玻璃载体表面,构建相应抗体的检测芯片,分别用于禽类不同类型禽流感病毒血清及随机选择的人血清检测,并对特异性、敏感性及重复性进行测试,与血凝抑制法进行双向验证比较。结果探针H1、H3、H5、N1、N2、NP、NS1亚型抗原的最佳浓度为1 mg/mL,H7、H9亚型抗原最佳浓度为0.5 mg/mL;检测禽类禽流感病毒及人禽流感病毒使用的酶标抗体浓度分别为1∶1 000和1∶1 500;方法具有较好的特异性,对H7N7阳性血清的检测限为1∶40稀释度;重复性检测的变异系数均<2%;血凝抑制法和蛋白芯片法的检测结果一致。结论所建立的蛋白芯片法可用于人类和禽类禽流感病毒的检测。     

Subcutaneous inoculation of a whole virus particle vaccine prepared from a non-pathogenic virus library induces protective immunity against H7N7 highly pathogenic avian influenza virus in cynomolgus macaques

Development of H7N7 highly pathogenic avian influenza virus (HPAIV) vaccines is an urgent issue since human cases of infection with this subtype virus have been reported and most humans have no immunity against H7N7 viruses. We made an H7N7 vaccine combining components from an influenza virus library of non-pathogenic type A influenza viruses. Antibody and T cell recall responses specific against the vaccine strain were elicited by subcutaneous inoculation with the whole virus particle vaccine with or without alum as an adjuvant in cynomolgus macaques. No significant difference was observed in magnitude of antibody responses between vaccination with alum and vaccination without alum, though vaccination with alum induced longer recall responses of CD8⁺ T cells than did vaccination without alum. After challenge with a subtype of H7N7 HPAIV, the virus was detected in nasal swabs of unvaccinated macaques for 8 days but only for 1 day in the animals vaccinated either with or without alum, although the macaques vaccinated with alum showed elevated body temperature more briefly after infection. These findings demonstrated that this H7N7 HPAIV strain is pathogenic to macaques and that the vaccine conferred protective immunity to macaques against H7N7 HPAIV infection.     

Examination of the effects of virus inactivation methods on the induction of antibody- and cell-mediated immune responses against whole inactivated H9N2 avian influenza virus vaccines in chickens

Several types of avian influenza virus (AIV) vaccines exist, including live-attenuated, vectored, and whole inactivated virus (WIV) vaccines. Inactivated vaccines offer some advantages compared to other types of vaccines, including ease of production and lack of ability to revert to a virulent state. However, WIV are poorly immunogenic, especially when these vaccines are delivered to mucosal surfaces. There are several factors that contribute to the immunogenicity of vaccines, one of which is the method used to inactivate viruses. Several methods exist for producing influenza WIVs, including formaldehyde, a chemical that affects protein structures leading to virus inactivation. Other methods include treatment with beta-propiolactone (BPL) and the application of gamma radiation, both of which have less effects on protein structures compared to formaldehyde, and instead alter nucleic acids in the virion. Here, we sought to determine the effect of the above inactivation methods on immunogenicity of AIV vaccines. To this end, chickens were vaccinated with three different H9N2 WIVs using formaldehyde, BPL, and gamma radiation for inactivation. In addition to administering these three WIVs alone as vaccines, we also included CpG ODN 2007, a synthetic ligand recognized by Toll-like receptor (TLR)21 in chickens, as an adjuvant for each WIV. Subsequently, antibody- and cell-mediated immune responses were measured following vaccination. Antibody-mediated immune responses were increased in chickens that received the BPL and Gamma WIVs compared to the formaldehyde WIV. CpG ODN 2007 was found to significantly increase antibody responses for each WIV compared to WIV alone. Furthermore, we observed the presence of cell-mediated immune responses in chickens that received the BPL WIV combined with CpG ODN 2007. Based on these results, the BPL WIV + CpG ODN 2007 combination was the most effective vaccine at inducing adaptive immune responses against H9N2 AIV. Future studies should characterize mucosal adaptive immune responses to these vaccines.     

H7 avian influenza virus vaccines protect chickens against challenge with antigenically diverse isolates

Vaccination has been a critical tool in the control of some avian influenza viruses (AIV) and has been used routinely in Pakistan to help control sporadic outbreaks of highly pathogenic (HP) H7 AIV since 1995. During that time, several AIV isolates were utilized as inactivated vaccines with varying degrees of success. In order to evaluate which H7 AIV strains may serve as optimal vaccines for diverse H7 AIVs from Pakistan we conducted vaccination-challenge studies with five H7 vaccines against challenge with two HPAIVs: A/chicken/Murree/NARC-1/1995 H7N3 and A/chicken/Karachi/SPVC-4/2004 H7N3. To further characterize the isolates antigenic cartography was used to visually demonstrate the antigenic relationships among the isolates. All vaccines provided similar protection against mortality, morbidity and shedding of challenge virus from the respiratory tract. However, some minor (not statistically significant) differences were observed and correlated with antibody levels induced by the vaccine prior to challenge.     

The stability and immunogenicity of inactivated MDCK cell-derived influenza H7N9 viruses

In recent years, cell-based influenza vaccines have gained a great interest over the egg-based vaccines. Several inactivated H7N9 vaccines have been evaluated in clinical trials, including whole-virion vaccines, split vaccines and subunit vaccines. Recently, we developed a new suspension MDCK (sMDCK) cell line for influenza viruses production. However, the properties of purified antigen from sMDCK cells remain unclear. In this study, the stability of influenza H7N9 vaccine bulk derived from sMDCK cells was investigated, and the data were compared with the vaccine antigen derived from our characterized adhesion MDCK (aMDCK) cells in serum-free medium. The influenza H7N9 bulks derived from sMDCK and aMDCK cells were stored at 2–8 °C for different periods of time, and a number of parameters selected to monitor the H7N9 vaccine antigen stability were evaluated at each interval (1, 3 and 12 months). The monitored parameters included virus morphology, hemagglutinin (HA) activity, HA concentration, antigenicity, and immunogenicity. The sMDCK-derived H7N9 bulk showed similar morphology to that of the aMDCK-derived H7N9 bulk, and there were no obvious changes after the extended storage periods. Furthermore, the HA titer, HA concentration, and antigenicity of sMDCK-derived H7N9 bulk were stable after 28 months of storage. Finally, the results of hemagglutination inhibition and neutralization tests showed that sMDCK- and aMDCK-derived H7N9 vaccines had comparable immunogenicity. These results indicated that sMDCK-derived H7N9 bulk has good stability compared to that of aMDCK-derived H7N9 bulk. Thus, the newly developed suspension MDCK cell line shows a great alternative for manufacturing cell-based influenza vaccines.