流感通用疫苗的研究现状与展望

流感在全球范围内的不断暴发引起了世界的高度关注。预防流感最有效和最经济的手段是疫苗免疫。流感病毒的多宿主和高度变异性,使得流感疫苗的有效性受到限制。目前使用的疫苗只对与疫苗株相同或高度相近的病毒株具有保护效力。一旦变异较大或新亚型的流感病毒出现,现有疫苗就会失去其保护效力。因此,研制一种可抵御变异较大或不同亚型流感病毒的通用疫苗成为流感疫苗研究的热点。选择流感病毒的保守蛋白做抗原是研制流感通用疫苗的主要方法,已有至少3种流感通用疫苗进入临床研究阶段。改变疫苗免疫途径和免疫程序,也能提高疫苗的交叉免疫效果。本文对流感通用疫苗的研究进展进行了综述与展望。     

广谱流感疫苗的研究进展

流行性感冒(简称流感)的频频暴发严重危害人类健康和公共卫生,已引起全球范围内的高度关注。预防流感最有效和经济的措施是接种疫苗,但流感病毒的持续变异可逃逸人群已有的免疫应答,目前使用的季节性流感疫苗仅对亚型内抗原匹配较好的毒株产生免疫保护作用,难以有效应对因抗原漂移或抗原转换而产生的无法预料的流感大流行。因此,研发对流感病毒不同亚型均具有交叉免疫保护作用的广谱流感疫苗具有重要意义。近年来,流感病毒广谱中和抗体的发现、对流感病毒抗原保守区域及细胞免疫机制的深入研究、疫苗免疫策略的优化等都为广谱流感疫苗的研发提供了新思路。本文简述了近几年基于血凝素、基质蛋白、核蛋白等多种流感靶抗原的广谱流感疫苗的研究进展。     

保护性抗体存在时细胞免疫反应对雪貂感染1918年流感的保护作用

研究感染人的高致病性流感的保护性免疫反应,对研发下一代的流感疫苗有重要的提示作用。鉴于此,采用不同的免疫方式对雪貂进行免疫,分别有:一针免疫传统疫苗;两针免疫表达HA的DNA疫苗,或者先     

流感病毒DNA疫苗的研究进展

流感病毒是一种危害极大的病原体。常见的流感疫苗有灭活疫苗、减毒活疫苗。随着分子生物学技术的发展,流感DNA疫苗成为流感疫苗的一个重要发展方向。常见的流感DNA疫苗有血凝素(HA)、神经氨酸酶(NA)DNA疫苗、核壳蛋白(NP)、膜蛋白(M)DNA疫苗。联合使用细胞因子DNA对流感DNA疫苗的免疫效果有明显加强作用。众多试验表明,流感病毒DNA疫苗效果良好,其保护效果不逊于传统灭活疫苗,具有良好的发展前景。     

临床试验中的流感通用疫苗研发进展

人类与流感病毒的斗争史已经过去一百多年,在人群抗体选择的压力下,流感病毒不断发生突变、重组等方式的进化和流行,在流感病毒的危险因素下,人类的预防医学、病原生物学和疫苗学也取得了巨大进步。对流感通用疫苗的研发成为流感疫苗研发的下一个征程,同时需要全球范围内的广泛协作和科技发展。为此本文综述了近期流感通用疫苗的研究进展,并对已经进入临床试验阶段的通用疫苗进行了分析,为流感疫苗研究提供参考。     

应对流感全球疫苗供应商紧急行动

2005年是流感流行的年份,全世界的疫苗供应商在强化流感疫苗的供给、开发体制的同时,也正在加紧应对可能发生大流行的新型流感。     

通用流感疫苗研究进展

流感是一种对人类危害极大的传染病,接种疫苗被认为是预防流感的最有效手段。目前所用的流感疫苗主要是根据现行流行株的减毒或灭活病毒疫苗及基于流感血凝素和神经氨酸酶设计的重组蛋白质疫苗。但流感病毒变异大,易逃逸机体免疫监视,有效的疫苗须不断分离新流行株和不断更新疫苗免疫原。为解决这一问题,很多科学家一直在研究基于病毒高度保守性蛋白质、能够预防所有流感病毒毒株、可诱导持久保护性免疫的通用流感疫苗。我们对基于基质蛋白M2、核蛋白等的通用流感疫苗做一简要综述。     

基于血凝素(HA)的新型流感疫苗研究进展

新型广谱流感疫苗是预防和控制不断变异的流感病毒的重要手段。血凝素(HA)是流感病毒表面的糖蛋白,具有免疫原性,但其变异性强,是A型流感病毒发生抗原变异的主要原因。近年来研究发现,HA存在保守的恒定区,可诱导机体产生流感病毒特异性广谱中和抗体,拮抗多种流感病毒的感染。因此,如何采取不同策略和方法,研发基于HA的新型疫苗成为流感防治研究的重点。就基于HA的新型流感疫苗研究进展作一综述。     

甲型流感病毒M2e通用疫苗的研究进展

流感严重地影响人们的身体健康和工作生活,给社会带来巨大经济损失。疫苗接种是预防流感的有效措施之一,市场上的流感疫苗包括流感灭活疫苗、减毒活疫苗和亚单位疫苗等。这些流感疫苗只能预防相同亚型流感病毒的感染,无法预防不同亚型流感病毒引起的季节性流感和流感大流行,因此迫切需要研发广谱的能预防不同亚型的甲型流感病毒感染的通用疫苗。在此简要介绍甲型流感病毒M2e通用疫苗的研究进展。     

三价亚单位《流感疫苗》的免疫原性和预防效果

<正>在疫苗预防流感的文献中,用多价亚单位疫苗接种的人获得抗体维持的时间,以及为建立和巩固对流感的免疫屏障进行第二次加强接种的实际意义报导很少。有关用多价亚单位疫苗降低流感发病率实际可能性的资料也很少。为此,本文报告了流感疫苗制剂的免疫原性和预防流感的情况。     

Antibody Persistence in Adults Two Years after Vaccination with an H1N1 2009 Pandemic Influenza Virus-Like Particle Vaccine

The influenza virus is a human pathogen that causes epidemics every year, as well as potential pandemic outbreaks, as occurred in 2009. Vaccination has proven to be sufficient in the prevention and containment of viral spreading. In addition to the current egg-based vaccines, new and promising vaccine platforms, such as cell culture-derived vaccines that include virus-like particles (VLPs), have been developed. VLPs have been shown to be both safe and immunogenic against influenza infections. Although antibody persistence has been studied in traditional egg-based influenza vaccines, studies on antibody response durations induced by VLP influenza vaccines in humans are scarce. Here, we show that subjects vaccinated with an insect cell-derived VLP vaccine, in the midst of the 2009 H1N1 influenza pandemic outbreak in Mexico City, showed antibody persistence up to 24 months post-vaccination. Additionally, we found that subjects that reported being revaccinated with a subsequent inactivated influenza virus vaccine showed higher antibody titres to the pandemic influenza virus than those who were not revaccinated. These findings provide insights into the duration of the antibody responses elicited by an insect cell-derived pandemic influenza VLP vaccine and the possible effects of subsequent influenza vaccination on antibody persistence induced by this VLP vaccine in humans.     

Adjuvanted vaccines against influenza in the elderly

Influenza is an important public health issue,especially with the aging of the population,since the most serious consequences of the illness affect the elderly.Between 1979 and 2001,approximately 41000...     

Bacterially Produced Recombinant Influenza Vaccines Based on Virus-Like Particles

Although current influenza vaccines are effective in general, there is an urgent need for the development of new technologies to improve vaccine production timelines, capacities and immunogenicity. Herein, we describe the development of an influenza vaccine technology which enables recombinant production of highly efficient influenza vaccines in bacterial expression systems. The globular head domain of influenza hemagglutinin, comprising most of the protein''s neutralizing epitopes, was expressed in E. coli and covalently conjugated to bacteriophage-derived virus-like particles produced independently in E.coli. Conjugate influenza vaccines produced this way were used to immunize mice and found to elicit immune sera with high antibody titers specific for the native influenza hemagglutinin protein and high hemagglutination-inhibition titers. Moreover vaccination with these vaccines induced full protection against lethal challenges with homologous and highly drifted influenza strains.     

Novel Viral Vectored Vaccines for the Prevention of Influenza

Influenza represents a substantial global healthcare burden, with annual epidemics resulting in 3–5 million cases of severe illness with a significant associated mortality. In addition, the risk of a virulent and lethal influenza pandemic has generated widespread and warranted concern. Currently licensed influenza vaccines are limited in their ability to induce efficacious and long-lasting herd immunity. In addition, and as evidenced by the H1N1 pandemic in 2009, there can be a significant delay between the emergence of a pandemic influenza and an effective, antibody-inducing vaccine. There is, therefore, a continued need for new, efficacious vaccines conferring cross-clade protection—obviating the need for biannual reformulation of seasonal influenza vaccines. Development of such a vaccine would yield enormous health benefits to society and also greatly reduce the associated global healthcare burden. There are a number of alternative influenza vaccine technologies being assessed both preclinically and clinically. In this review we discuss viral vectored vaccines, either recombinant live-attenuated or replication-deficient viruses, which are current lead candidates for inducing efficacious and long-lasting immunity toward influenza viruses. These alternate influenza vaccines offer real promise to deliver viable alternatives to currently deployed vaccines and more importantly may confer long-lasting and universal protection against influenza viral infection.     

Strategies for developing vaccines against H5N1 influenza A viruses

Recent outbreaks of highly pathogenic avian influenza A virus (H5N1 subtype) infections in poultry and humans (through direct contact with infected birds) have raised concerns that a new influenza pandemic might occur in the near future. Effective vaccines against H5N1 virus are, therefore, urgently needed. Reverse-genetics-based inactivated vaccines have been prepared according to World Health Organization (WHO) recommendations and are now undergoing clinical evaluation in several countries. Here, we review the current strategies for the development of H5N1 influenza vaccines, and future directions for vaccine development.     

Towards universal influenza vaccines?

Vaccination is the most cost-effective way to reduce the considerable disease burden of seasonal influenza. Although seasonal influenza vaccines are effective, their performance in the elderly and immunocompromised individuals would benefit from improvement. Major problems related to the development and production of pandemic influenza vaccines are response time and production capacity as well as vaccine efficacy and safety. Several improvements can be envisaged. Vaccine production technologies based on embryonated chicken eggs may be replaced by cell culture techniques. Reverse genetics techniques can speed up the generation of seed viruses and new mathematical modelling methods improve vaccine strain selection. Better understanding of the correlates of immune-mediated protection may lead to new vaccine targets besides the viral haemagglutinin, like the neuraminidase and M2 proteins. In addition, the role of cell-mediated immunity could be better exploited. New adjuvants have recently been shown to increase the breadth and the duration of influenza vaccine-induced protection. Other studies have shown that influenza vaccines based on different viral vector systems may also induce broad protection. It is to be expected that these developments may lead to more universal influenza vaccines that elicit broader and longer protection, and can be produced more efficiently.     

Structural vaccinology: structure-based design of influenza A virus hemagglutinin subtype-specific subunit vaccines

There is a great need for new vaccine development against influenza A viruses due to the drawbacks of traditional vaccines that are mainly prepared using embryonated eggs. The main component of the current split influenza A virus vaccine is viral hemagglutinin (HA) which induces a strong antibody-mediated immune response. To develop a modern vaccine against influenza A viruses, the current research has been focused on the universal vaccines targeting viral M2, NP and HA proteins. Crystallographic studies have shown that HA forms a trimer embedded on the viral envelope surface, and each monomer consists of a globular head (HA1) and a “rod-like” stalk region (HA2), the latter being more conserved among different HA subtypes and being the primary target for universal vaccines. In this study, we rationally designed the HA head based on the crystal structure of the 2009-pandemic influenza A (H1N1) virus HA as a model, tested its immunogenicity in mice, solved its crystal structure and further examined its immunological characteristics. The results show that the HA globular head can be easily prepared by in vitro refolding in an E. coli expression system, which maintains its intact structure and allows for the stimulation of a strong immune response. Together with recent reports on some similar HA globular head preparations we conclude that structure-based rational design of the HA globular head can be used for subtype-specific vaccines against influenza viruses.     

A reassortment-incompetent live attenuated influenza virus vaccine for protection against pandemic virus strains

Although live-attenuated influenza vaccines (LAIV) are safe for use in protection against seasonal influenza strains, concerns regarding their potential to reassort with wild-type virus strains have been voiced. LAIVs have been demonstrated to induce enhanced mucosal and cell-mediated immunity better than inactivated vaccines while also requiring a smaller dose to achieve a protective immune response. To address the need for a reassortment-incompetent live influenza A virus vaccine, we have designed a chimeric virus that takes advantage of the fact that influenza A and B viruses do not reassort. Our novel vaccine prototype uses an attenuated influenza B virus that has been manipulated to express the ectodomain of the influenza A hemagglutinin protein, the major target for eliciting neutralizing antibodies. The hemagglutinin RNA segment is modified such that it contains influenza B packaging signals, and therefore it cannot be incorporated into a wild-type influenza A virus. We have applied our strategy to different influenza A virus subtypes and generated chimeric B/PR8 HA (H1), HK68 (H3), and VN (H5) viruses. All recombinant viruses were attenuated both in vitro and in vivo, and immunization with these recombinant viruses protected mice against lethal influenza A virus infection. Overall, our data indicate that the chimeric live-attenuated influenza B viruses expressing the modified influenza A hemagglutinin are effective LAIVs.     

Pandemic Influenza H1N1 2009, Innate Immunity,and the Impact of Immunosenescence on Influenza Vaccine

Seasonal and pandemic strains of influenza have widespread implications for the global economy and global health. This has been highlighted recently as the epidemiologic characteristics for hospitalization and mortality for pandemic influenza H1N1 2009 are now emerging. While treatment with neuraminidase inhibitors are effective for seasonal and pandemic influenza, prevention of morbidity and mortality through effective vaccines requires a rigorous process of research and development. Vulnerable populations such as older adults (i.e., > age 65 years) suffer the greatest impact from seasonal influenza yet do not have a consistent seroprotective response to seasonal influenza vaccines due to a combination of factors. This short narrative review will highlight the emerging epidemiologic characteristics of pandemic H1N1 2009 and focus on immunosenescence, innate immune system responses to influenza virus infection and vaccination, and influenza vaccine responsiveness as it relates to seasonal and H1N1 pandemic influenza vaccines.