Host dependence of influenza A virus reassortment

当两种甲型流感病毒(IAV)共同感染同一细胞时，通过 重新排序产生了多达256种不同的病毒变体。这一进程有可能将 在不同的宿主物种中进化的病毒基因，这反过来可以促进人畜共患病的转移。在主机中 感染了单个病毒群体，重新排序可以进一步结合有益的突变或清除 有害的病毒，从而加速病毒的进化。使用一种独特的实验系统，允许直接 重组的量化，我们已经证明了这种基因交换过程在细胞中是高效的 培养和在豚鼠宿主中。事实上，从合并感染的几内亚中分离出的重组病毒的流行 猪(高达75%)表明，重新分类是自然界IAV感染的常规特征。IAV在一个 然而，鸟类和哺乳动物的种类繁多，目前还不清楚我们在几内亚的发现 猪会延伸到这些自然宿主。因此，我们建议评估重新分类的效率在 猪、绿头鸭、鹌鹑和鸡。雪貂和豚鼠也将被列为人类IAV的模型 感染。通过比较不同物种的结果，我们不仅将获得重要的洞察力 自然寄主的重新分类，但也检验了重新分类的效率在不同的寄主之间变化的假设 寄主物种。为了研究体内决定IAV重组效率的机制，我们将使用 免疫组织化学跟踪联合感染病毒在接种后一段时间内的传播情况。我们 假设重组有利于靶组织内的焦点扩散，创建局部区域，细胞 以高度的多样性被感染。最后，由于我们在细胞培养方面的工作揭示了病毒基因组缺乏 一个或多个片段明显增加重新排序的频率，我们将测试是否流行 不完全病毒基因组的比例因宿主物种而异。我们的初步数据强烈表明，失踪的 片段丢失，不是在病毒粒子组装过程中，而是在基因组被传递到新的靶细胞之后。这个 此外，片段到达复制位置的可能性似乎取决于来自 从中派生出目标单元格。因此，我们认为，重新分类水平可能部分取决于宿主 不同频率的不完全病毒基因组，并将通过实验测试这一新概念 在细胞培养和动物模型中都是如此。总体而言，提出的研究将深化机械论 对IAV重新分类的理解，这是小说多样化、演变和出现的关键过程 甲型流感病毒。

When two influenza A viruses (IAVs) co-infect the same cell, exchange of gene segments through reassortment gives rise to up to 256 different viral variants. This process has the potential to bring together viral genes that have evolved in distinct host species, which in turn can facilitate zoonotic transfer. In a host infected with a single virus population, reassortment can furthermore couple beneficial mutations or purge deleterious ones, thereby accelerating viral evolution. Using a unique experimental system that allows direct quantification of reassortment, we have shown that this process of genetic exchange is highly efficient in cell culture and in a guinea pig host. Indeed, the prevalence of reassortant viruses shed from co-infected guinea pigs (up to 75%) suggests that reassortment is a routine feature of IAV infections in nature. IAVs circulate in a wide range of avian and mammalian species, however, and it remains unclear whether our findings in guinea pigs would extend to these natural hosts. We therefore propose to evaluate the efficiency of reassortment in pigs, mallards, quail and chickens. Ferrets and guinea pigs will also be included as models of human IAV infection. By comparing results among species we will not only gain important insight into the incidence of reassortment in natural hosts, but also test the hypothesis that the efficiency of reassortment varies among host species. To investigate the mechanisms determining IAV reassortment efficiency in vivo, we will use immunohistochemistry to track the spread of co-infecting viruses over a time course after inoculation. We hypothesize that reassortment is favored by focal spread within target tissues, creating local areas where cells are infected at high multiplicity. Finally, since our work in cell culture has revealed that viral genomes lacking one or more segments markedly enhance the frequency of reassortment, we will test whether the prevalence of incomplete viral genomes varies with host species. Our preliminary data strongly suggest that missing segments are lost, not during virion assembly, but rather after genomes are delivered to a new target cell. The likelihood of segments reaching the site of replication furthermore appears to depend on the species from which the target cell is derived. Thus, we propose that reassortment levels may be host dependent in part due to differing frequencies of incomplete viral genomes and will test this novel concept through experimentation both in cell culture and in animal models. Overall, the research proposed will deepen mechanistic understanding of IAV reassortment, a critical process in the diversification, evolution and emergence of novel influenza A viruses.