Vaccines for Pandemic Influenza

大流行性流感疫苗

• 批准号: 7196717
• 负责人: Kanta Subbarao
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7196717
• 关键词: attenuated microorganism; biotechnology; chickens; communicable disease control; exo alpha sialidase; ferrets; hemagglutinin; influenza vaccines; influenzavirus A; laboratory mouse; polymerase chain reaction; recombinant virus; serology /serodiagnosis; tissue /cell culture; vaccine development; vaccine evaluation; viral vaccines; virus infection mechanism

Influenza A viruses are divided into subtypes on the basis of the antigenicity of their surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA); influenza viruses bearing 15 HA and 9 NA subtypes have been isolated from birds, but only H1N1, H2N2, and H3N2 subtype viruses have circulated widely and caused epidemic disease in humans in the last century. Aquatic birds serve as a reservoir from which new subtypes of influenza A viruses enter the human population. In the last 10 years, human infections with avian influenza viruses (AIV) of three subtypes, H7, H5 and H9, have been detected on several occasions, accompanied in each case by contemporaneous outbreaks of disease in poultry. In 2003, a large outbreak of human infections with a highly pathogenic avian influenza H7N7 virus occurred in Europe. On several occasions since 1997, there have been serious outbreaks caused by a highly pathogenic avian influenza H5N1 viruses in Asia. The most recent H5N1 outbreak in poultry began in late 2003 and affected at least 10 countries in Asia. Recent reports indicate that H5N1 viruses have been isolated from migratory and wild birds in China, Russia, Kazakhstan, Mongolia and Tibet. Human cases of H5N1 infection have been reported since December 2003 in Indonesia, Vietnam, Thailand and Cambodia with a total of 112 cases and 57 deaths as of August 5, 2005. There are several potential strategies for the development of vaccines to protect humans against influenza viruses, including formalin inactivated whole or split virus, HA subunit, and live attenuated vaccines. Live attenuated vaccines generally induce broadly cross-reactive protection, which may be a useful feature in the event of a pandemic if a vaccine generated from the actual pandemic strain is not available. The goal of our program is to generate candidate live attenuated reassortant influenza virus vaccines against a range of influenza A subtypes that have pandemic potential and to evaluate these vaccines in preclinical studies and clinical trials. The vaccine viruses will contain the hemagglutinin (HA) and neuraminidase (NA) genes of a selected avian influenza virus with pandemic potential and the attenuating genes from the A/Ann Arbor/6/60 cold adapted (A/AA/6/60 ca) donor virus. The cold-adapted (ca) influenza virus A/Ann Arbor/6/60 (AA) (H2N2) has been developed as a live attenuated vaccine seed virus that exhibits cold-adaptation, temperature-sensitive (ts), and attenuation (att) phenotypes which are specified by mutations in the internal genes. Reassortant H1N1 and H3N2 human influenza A viruses with the six internal gene segments of the AA ca virus have been repeatedly demonstrated to bear these phenotypes and extensive evaluation in humans has proven them to be attenuated and safe as live virus vaccines. This approach has been licensed for general use for interpandemic influenza A and B virus infections. It is not known whether the candidate vaccine viruses bearing avian influenza HA and NA genes will be over-attenuated for humans or will be associated with some residual virulence. Live attenuated vaccines must be able to replicate to levels that elicit a protective immune response without causing disease in the host so a balance between attenuation and infectivity must be achieved. An optimal public health response in the event of a potential pandemic requires that vaccines be available to prevent infection with minimum delay and an important approach to pandemic preparedness is to generate and evaluate candidate vaccines against influenza A subtypes that are recognized to have pandemic potential, prior to their actual spread. We generated a candidate H9N2 influenza vaccine by genetic reassortment; the vaccine strain contains the hemagglutinin and neuraminidase genes from an avian H9N2 influenza virus and six internal gene segments from the AA ca virus. The candidate H9N2 vaccine virus demonstrated the ts, ca and att phenotypes of the AA ca vaccine donor virus. The H9N2 AA ca vaccine virus was immunogenic in mice and protected mice from subsequent challenge with homologous and heterologous H9N2 viruses. A clinical lot of this vaccine was generated and a Phase I clinical trial of the safety and immunogenicity of the vaccine for healthy adults was undertaken under an IND. Analysis of laboratory results from the clinical trial is under way. In order to generate candidate vaccines against H5N1 viruses that have caused human infections in Asia in 1997, 2003 and 2004, we applied plasmid based reverse genetics, a technique in which infectious virus can be recovered from cells co-transfected with plasmids expressing each of the 8 influenza gene segments, to generate reassortant viruses that contain the hemagglutinin and neuraminidase genes from H5N1 influenza viruses and six internal gene segments from the AA ca virus. We removed the virulence motif of multiple basic amino acid motifs in the hemagglutinin gene of the highly pathogenic H5N1 influenza virus that are associated with pathogenicity in poultry. The ts and ca phenotypes of the candidate pandemic vaccines will be evaluated in vitro and preclinical studies will be carried out in mice to determine the level of attenuation, immunogenicity and efficacy against challenge. Clinical trials of the H5N1 vaccines will focus on safety, infectivity and immunogenicity of the candidate influenza vaccines.

甲型流感病毒根据其表面糖蛋白、血凝素（HA）和神经氨酸酶（NA）的抗原性分为亚型;携带15种HA和9种NA亚型的流感病毒已从鸟类中分离，但只有H1N1、H2 N2和H3 N2亚型病毒在上个世纪广泛传播并在人类中引起流行性疾病。水生鸟类是甲型流感病毒新亚型进入人群的宿主。在过去10年中，曾数次发现人感染H7、H5和H9三种亚型禽流感病毒，每次都伴随着禽类疾病的同时爆发。2003年，欧洲发生了人感染高致病性禽流感H7 N7病毒的大规模爆发。自1997年以来，亚洲曾多次发生由高致病性禽流感H5 N1病毒引起的严重疫情。最近一次H5 N1禽流感爆发始于2003年底，至少影响到亚洲10个国家。最近的报告显示，H5 N1病毒已从中国、俄罗斯、哈萨克斯坦、蒙古和西藏的候鸟和野鸟中分离出来。自2003年12月以来，印度尼西亚、越南、泰国和柬埔寨报告了人类H5 N1感染病例，截至2005年8月5日，共有112例病例和57例死亡。 有几种潜在的策略用于开发疫苗以保护人类免受流感病毒的侵害，包括福尔马林灭活的完整或裂解病毒、HA亚单位和活减毒疫苗。减毒活疫苗通常诱导广泛的交叉反应性保护，这在大流行的情况下可能是一个有用的特征，如果从实际的大流行毒株产生的疫苗是不可用的。我们计划的目标是产生针对一系列具有大流行潜力的甲型流感亚型的候选减毒活流感病毒疫苗，并在临床前研究和临床试验中评估这些疫苗。疫苗病毒将含有具有大流行潜力的选定禽流感病毒的血凝素（HA）和神经氨酸酶（NA）基因以及来自A/安阿伯/6/60冷适应（A/AA/6/60 ca）供体病毒的减毒基因。冷适应（ca）流感病毒A/安阿伯/6/60（AA）（H2 N2）已被开发为减毒活疫苗种子病毒，其表现出由内部基因突变指定的冷适应、温度敏感（ts）和减毒（att）表型。具有AA ca病毒的六个内部基因片段的H1N1和H3 N2人类甲型流感病毒已被反复证明具有这些表型，并且在人类中的广泛评价已证明它们是减毒的并且作为活病毒疫苗是安全的。该方法已被许可用于甲型和B型流感病毒感染的一般用途。 目前尚不清楚携带禽流感HA和NA基因的候选疫苗病毒对人类是否会过度减毒，或者是否会残留一些毒力。减毒活疫苗必须能够复制到引起保护性免疫应答而不引起宿主疾病的水平，因此必须实现减毒和感染性之间的平衡。在发生潜在大流行的情况下，最佳的公共卫生应对措施要求在最短的时间内提供预防感染的疫苗，大流行防备的一个重要方法是在被认为具有大流行潜力的甲型流感亚型实际传播之前，生成和评估候选疫苗。 我们产生了一个候选人H9 N2流感疫苗的基因重组，疫苗株含有血凝素和神经氨酸酶基因从禽H9 N2流感病毒和六个内部基因片段从AA CA病毒。候选H9 N2疫苗病毒显示AA ca疫苗供体病毒的ts、ca和att表型。H9 N2 AA ca疫苗病毒在小鼠中具有免疫原性，并保护小鼠免受同源和异源H9 N2病毒的后续攻击。生产了该疫苗的一个临床批次，并根据IND对健康成人进行了该疫苗安全性和免疫原性的I期临床试验。 为了产生针对1997年、2003年和2004年在亚洲引起人类感染的H5 N1病毒的候选疫苗，我们应用了基于质粒的反向遗传学技术，在该技术中，感染性病毒可以从与表达8种流感基因片段中的每一种的质粒共转染的细胞中回收，以产生含有来自H5 N1流感病毒的血凝素和神经氨酸酶基因以及来自AA ca病毒的六个内部基因片段的重组病毒。我们去除了高致病性H5 N1流感病毒血凝素基因中与家禽致病性相关的多个碱性氨基酸基序的毒力基序。将在体外评价候选大流行性疫苗的ts和ca表型，并将在小鼠中进行临床前研究，以确定减毒水平、免疫原性和抗攻毒效力。H5 N1疫苗的临床试验将集中于候选流感疫苗的安全性、感染性和免疫原性。