Improved Vaccines for Influenza B Virus

描述（由申请人提供）：流感是全球发病率和死亡率的主要原因。在美国，流感的季节性流行发生在深秋到早春，影响所有年龄组，但儿童的感染率特别高。严重的疾病和死亡是老年人、幼儿和患有其他疾病的人感染流感的后果，这些疾病使他们易患流感并发症。接种疫苗是对抗流感感染和疾病的有效方法，但一些科学和技术考虑因素可能会对目前针对该病毒的疫苗接种策略产生负面影响。 由于流感病毒具有相当大的抗原漂移倾向，因此每个季节的疫苗中包含的病毒株经常改变以反映当前的流行病毒。抗原漂移的问题可能是生产“通用”或广泛交叉保护流感疫苗的最重要障碍。试图克服流感病毒株的多样性一直是许多努力的重点。 在本提案中，我们将尝试解决FDA已确定的与季节性疫苗的流感B病毒组分相关的特定问题。与甲型流感病毒不同，B型流感几乎只感染人类，并造成严重的流行病，幼儿住院率很高。多年来，人们已经认识到B型流感有两个谱系。虽然在每个谱系内存在抗原漂移，但序列多样性相对有限。然而，事实证明，很难预测哪种谱系将在特定的流感季节占主导地位，FDA建议将两种毒株都包括在季节性疫苗中，因此需要开发四价疫苗。 一个更简单的解决方案是创造一种B流感免疫原，诱导对两种谱系的交叉保护性免疫。我们建议使用定向分子进化的方法来解决这个问题。将使用编码已用于先前疫苗中的各种血凝素蛋白的基因的体外DNA重组来产生流感B血凝素的许多变体。用许多这些变体免疫小鼠并分析所得血清的中和能力将用于筛选符合所需标准的免疫原。虽然我们认识到流感血凝素序列的变化主要是通过点突变产生的，但几种可能性支持通过重组产生新的多样性可以提高免疫原性的想法。纯化可能将来自不同病毒变体的联合收割机表位或将保守的中和表位暴露到能够引发更广泛保护性应答的一种免疫原中。我们的主要目标是从新型流感B免疫原中获得完全交叉反应性中和应答;然而，次要目标是扩大应答范围以涵盖一个谱系的所有病毒。 公共卫生相关性：每年的流感季节都造成相当多的疾病和死亡，特别是在人口中较脆弱的成员中。由于流感病毒株每年都在变化，因此广泛发挥作用的疫苗将具有巨大价值。我们建议创造一种季节性疫苗的一种成分的改进版本，可以提供更好的保护，防止一些流感病毒。

DESCRIPTION (provided by applicant): Influenza is a major cause of morbidity and mortality around the world. In the United States, seasonal epidemics of flu occur from late fall to early spring affecting all age groups but with especially high rates of infection in children. Serious illness and death are consequences of influenza infection among the elderly, young children, and individuals with other illnesses that predispose them form complication of influenza. Vaccination is an effective way to counter influenza infection and illness, but several scientific and technical considerations can negatively impact the current strategies for vaccination against this virus. Because of the antigenic drift for which the influenza virus has a considerable propensity, the strain of virus included in each season's vaccine is frequently change to reflect the current circulating virus. The issue of antigenic drift is perhaps the most significant impediment to the production of a "universal" or broadly cross- protective vaccine to influenza. Attempts to overcome the diversity of influenza strains have been the focus of many efforts. In this proposal we will attempt to solve a particular problem that has been identified by the FDA related to the influenza B virus component of the seasonal vaccine. Unlike influenza A viruses, influenza B infects almost exclusively humans and has been responsible for severe epidemics with high rates of hospitalization for young children. Two lineages of influenza B have been recognized for many years. Although there is antigenic drift within each lineage, the sequence diversity is relatively limited. However, it has proven to be difficult to forecast which lineage will dominate a given flu season and the FDA has suggested that both strains be included in the seasonal vaccine, thus requiring a quadrivalent vaccine to be developed. A simpler solution would be to create an influenza B immunogen that induces cross-protective immunity to both lineages. We propose to use a directed molecular evolution approach to address this problem. Many variants of influenza B hemagglutinin will be created using in vitro DNA recombination of the genes encoding the various hemagglutinin proteins that have been used in previous vaccines. Immunization of mice with many of these variants and analysis of the neutralizing capability of the resulting serum will be used to screen for immunogens that meet the desired criteria. Although we are cognizant of the fact that changes in influenza hemagglutinin sequences arise largely through point mutation, several possibilities support the idea that creation of novel diversity by recombination can improve immunogenicity. Recombination might combine epitopes from different viral variants or expose conserved neutralizing epitopes into one immunogen capable of eliciting broader protective responses. Our primary objective is to have a fully cross-reactive neutralizing response from a novel influenza B immunogen; however, a secondary objective is to broaden the response to cover all viruses of one lineage. PUBLIC HEALTH RELEVANCE: The annual influenza season is responsible for considerable sickness and death, especially among the more vulnerable members of the population. Since flu strains change from year to year, a vaccine that acts broadly would be of great value. We propose to create an improved version of one of the components of the seasonal vaccine that can provide better protection against some of the flu viruses.