Function of NALT in nasal immunization to heterotypic strains of influenza

描述（由申请人提供）：感冒适应流感疫苗（CAV）是感染上呼吸道的减毒活病毒，包括鼻相关淋巴组织（NALT）。由于NALT是一种粘膜淋巴样器官，因此推测它可以指导最有效保护呼吸道的B细胞和T细胞的发育。尽管CAV流感疫苗具有潜在的益处，但由于担心当代流感毒株与疫苗毒株之间的重组，使用这些疫苗引起对人畜共患病毒（如H5N1禽流感）的免疫受到限制。此外，CAV流感疫苗未被批准用于儿童或老年人。因此，开发像CAV一样能引起异型免疫并针对NALT和呼吸道的疫苗是可取的。然而，人们对NALT的实际功能知之甚少，NALT在CAV免疫应答中的作用也从未被测试过。因此，本提案的总体目标是专门评估鼻内递送重组蛋白和冷适应流感病毒（CAV）引起的NALT的免疫反应。我们将确定针对CAV或蛋白抗原的免疫反应是否在NALT中启动，NALT的启动是否赋予T细胞粘膜归巢特性，以及T细胞是否在NALT中启动后归巢到肺组织和气道。我们还将确定对CAV的免疫反应是否会诱导CD4 T细胞在功能上不同于用蛋白质鼻腔接种引起的CD4 T细胞。此外，我们将确定鼻内接种CAV或蛋白抗原是否会诱导m2e特异性B细胞进入上呼吸道和下呼吸道。我们还将测试来自CAV或重组蛋白的抗原如何在NALT中传递到淋巴细胞，M细胞是否参与这一过程，以及NALT中的M细胞是否与Peyer's patches NALT中的M细胞相似。最后，我们将确定用CAV或蛋白抗原进行鼻内免疫是否会导致对强毒性异型流感株的长期免疫。与公共卫生的相关性：甲型流感病毒是一种重要的人类自然病原体，在美国每年平均造成35,000人死亡。此外，特别致命的流感病毒会周期性出现，并在一个季节内造成数百万人死亡。这些新出现的流感毒株，如1997年在香港出现的高毒力H5N1变种，有可能引发另一场全球大流行，造成毁灭性的社会和经济后果。因此，我们必须开发能够预防多种流感血清型的疫苗。本提案描述了将确定鼻内接种感冒适应病毒或纯化蛋白促进流感免疫的机制的实验。这一信息对于开发疫苗至关重要，这些疫苗可促进对流感病毒的长期交叉反应免疫，流感病毒仍然是一种新出现的传染病。

DESCRIPTION (provided by applicant): Cold adapted influenza vaccines (CAV) are live attenuated viruses that infect the upper respiratory tract, including the Nasal Associated Lymphoid Tissue (NALT). Since NALT is a mucosal lymphoid organ, it is presumed to direct the development of B and T cells that most effectively protect the respiratory tract. Despite the potential benefits of CAV influenza vaccines, the use of these vaccines to elicit immunity to zoonotic viruses, such as H5N1 avian influenza, is limited due to the fear of recombination between contemporary influenza strains and the vaccine strain. In addition, CAV influenza vaccines are not approved for children or the elderly. Thus, it is desirable to develop vaccines that, like CAV, can elicit heterotypic immunity and target the NALT and respiratory tract. However, the actual function of NALT is poorly understood and the role of NALT in immune responses to CAV has never been tested. Therefore, the overall goal of this proposal is to specifically evaluate immune responses in NALT elicited by intranasally delivered recombinant protein and cold-adapted influenza virus (CAV). We will determine whether immune responses to CAV or protein antigens are initiated in NALT, whether priming in NALT confers mucosal homing properties on T cells and whether T cells primed in NALT home to the lung tissue and airways. We will also determine whether immune responses to CAV elicit CD4 T cells that are functionally different than those elicited by nasal vaccination with proteins. Moreover, we will determine whether intranasal vaccination with CAV or protein antigens elicit M2e-specific B cells that home to the upper and lower respiratory tract. We will also test how antigens from CAV or recombinant proteins are delivered to lymphocytes in NALT, whether M cells are a part of this process and whether M cells in NALT are similar to those in Peyer's patches NALT. Finally, we will determine whether intranasal immunization with CAV or protein antigens results in long-lived immunity to virulent, heterotypic strains of influenza. Relevance to public health: Influenza A virus is a significant natural pathogen of man that is responsible for an average of 35,000 deaths annually in the US. In addition, particularly virulent influenza viruses periodically emerge and cause millions of deaths in a single season. These emerging strains of influenza, such as the highly virulent H5N1 variant that appeared in Hong Kong in 1997, have the potential to trigger another worldwide pandemic with devastating social and economic consequences. Thus, it is imperative that we develop vaccines that are protective against a wide array of influenza serotypes. This proposal describes experiments that will determine the mechanisms by which intranasal vaccination with cold adapted viruses or purified proteins promote immunity to influenza. This information will be essential for the development of vaccines that promote long-lasting cross-reactive immunity to influenza, a virus that continues to be an emerging infectious disease.