Replication of Highly Pathogenic Avian Influenza Viruses in Swine

描述（由申请人提供）：高致病性禽流感（HPAI）H5N1病毒从鸟类向人类的零星传播已导致许多人死亡。迄今为止，H5N1病毒在人与人之间的传播效率不高，但该病毒获得有效的人与人之间传播能力的一个可能机制是它适应了猪的水平传播。关于猪对高致病性禽流感H5N1病毒感染的容许性知之甚少。先前的研究表明，病毒的种间传播可导致病毒变异体的快速选择。我们的长期目标是研究病毒在一系列宿主中传播能力的分子基础以及流感病毒致病性的分子基础。本研究的主要目的是确定猪对亚洲高致病性禽流感病毒株H5N1感染的容许程度及其在大流行病毒株出现中的潜在作用。1）确定宿主对H5N1感染的临床、病理和免疫反应：将通过监测临床症状、使用血凝抑制和病毒中和试验测量抗体反应以及使用免疫组织化学（IHC）进行组织病理学检查，评估病毒在猪体内复制和致病的能力。2)确定3 HPAI H5N1病毒复制的时间进程和感染性病毒在猪主要器官系统中的浓度：将通过使用IHC检测抗原和使用标准程序检测50%鸡蛋感染剂量的病毒浓度来评估病毒在主要器官中传播的能力。3)确定粘膜病毒复制和脱落的位点：通过IHC检测抗原的细胞分布和原位杂交检测病毒RNA，确定病毒在主要器官中复制的能力。4)确定3种HPAI H5N1毒株经口腔和咽部暴露的最小感染剂量：通过用1至4 log10 EID的剂量感染猪并确定50%猪感染剂量进行。5)生成起始材料，以确定与猪复制相关的分子事件以及遗传和抗原分析：将生成病毒原液和各种组织样本，用于进一步的分子分析。我们的努力将对预防和控制全球动物和人类禽流感爆发产生重大影响。从这项研究中获得的新知识可能会导致开发新的抗病毒疗法，这可能会改善受流感影响的个体的人类健康。

DESCRIPTION (provided by applicant): Sporadic transmission of highly pathogenic avian influenza (HPAI) H5N1 viruses from birds to humans has resulted in many deaths. Person to person transmission of the H5N1 virus has been inefficient so far, but a possible mechanism for the virus to acquire efficient person to person transmission capacity would be its adaptation to horizontal transmission in pigs. Little is known about the permissiveness of swine to infection with HPAI H5N1 viruses. Previous studies have shown that interspecies transmission of viruses can result in the rapid selection of virus variants. Our long-term goal is to study the molecular bases of a virus's ability to spread among a range of hosts and of the pathogenicity of influenza viruses. The main goal of this study is to establish the degree of permissiveness of swine to infection with Asian strains of HPAI H5N1 and their potential role in the emergence of pandemic strains. This proposal addresses the following objectives: 1) Define clinical, pathologic, immunologic responses of the host to H5N1 infection: virus ability to replicate and cause disease in pigs will be evaluated by monitoring clinical signs, measuring antibody response using hemagglutination inhibition and virus neutralization assays, and histopathology by immunohistochemistry (IHC). 2) Define a time course of 3 HPAI H5N1 virus replication and concentration of infectious virus in the major organ systems of swine: virus ability to disseminate in major organs will be evaluated by detecting antigen using IHC and the concentration of the virus by 50% egg infectious dose using standard procedures. 3) Determine sites of mucosal virus replication and shedding: virus ability to replicate in major organs is determined by detecting cellular distribution of antigen by IHC and viral RNA by in situ hybridization. 4) Determine the minimal infectious dose for 3 HPAI H5N1 strains via oral and pharyngeal exposure: This is performed by infecting pigs with doses from 1 to 4 log10 EID and determining the 50% pig infectious dose. 5) Generate starting materials to define molecular events and genetic and antigenic analyses associated with replication in swine: virus stocks & various tissue samples will be generated for further molecular analyses. Our efforts will have a major impact on the prevention and control of global outbreaks of avian influenza in animals and humans. The new knowledge gained from this study may lead to the development of novel antiviral therapies that would potentially improve human health in individuals affected by influenza.