Viral entry at the human-animal interface; dissecting the pan-tropic nature of zoonotic viruses.

土地使用模式的人为变化、栖息地的破坏和气候变化增加了SARS-CoV-2等病毒（COVID-19的病原体）蔓延到人类和/或动物体内的可能性。反过来，城市化和全球旅行的增加，群体免疫力的缺乏和准备不足可能导致局部流行病转变为全球大流行病。然而，自然界中并非所有病毒都具有相同的溢出倾向;有些病毒仅限于个别宿主，而另一些病毒的宿主范围很广，对人类和/或动物（牲畜、宠物和野生动物）的风险要大得多。更好地了解决定病毒“人畜共患病潜力”的因素，尤其具有先见之明，因为我们希望在后COVID-19环境中改善大流行的准备工作。在这种情况下，需要理解的最重要的因素之一是病毒进入（病毒附着并侵入宿主细胞的过程）与人畜共患病潜力之间的关系。一般来说，病毒使用特定的受体（蛋白质或糖）进入细胞。这些可以在宿主之间变化，代表直接影响宿主范围和溢出可能性的重要限制点。对病毒的整个分类群（属或科）的这种关系的理解将有助于科学家和利益相关者评估哪些病毒对人类和动物的风险最大。在广泛的水平上表征病毒受体的使用和宿主范围在技术上具有挑战性。例如，选择准确代表其家族整体多样性的病毒容易产生偏见，有利于建立病原体而不是在其天然蝙蝠或啮齿动物宿主中分离的病原体。为了解决这个问题，我们开发并优化了一个管道，该管道利用生物信息学算法来无偏见地选择代表性病毒。在本项目中，我们将使用这种方法来验证冠状病毒和沙粒病毒家族的人畜共患病潜力。所有的人类冠状病毒，以及许多感染我们的宠物和牲畜的冠状病毒，都被认为具有人畜共患病的起源（蝙蝠或啮齿动物）。沙粒病毒也是如此，像拉沙病毒这样的病毒不断从啮齿动物的宿主中溢出。作为原理证明，我们已经收集了麻疹病毒属的数据集，发现了一些有趣的限制，这些限制可以解释这个较小的病毒组（属）的宿主范围较窄。我们的实验管道将如下进行：一旦我们选择了代表性的病毒，我们将使用一系列最先进的技术来量化它们的受体使用和宿主范围。随后，我们将使用诱变和蛋白结合实验来剖析这种人畜共患病潜力的遗传决定因素。组建的科学研究团队对这一领域有着长期的兴趣，对麻疹病毒、冠状病毒和沙粒病毒家族有着广泛而重叠的兴趣。以前，我们已经确定了动物麻疹病毒附着蛋白的氨基酸变化，这些蛋白向人类受体传递向性，解决了沙粒病毒附着蛋白的结构，最近还研究了SARS-CoV-2可能的蝙蝠起源。我们在该项目中产生的信息将用于改善我们的大流行准备，帮助我们识别具有广泛宿主范围的高风险病原体（基于入境）。最终，这些信息可以用来设计新的药物和疫苗，希望能预防人类和动物未来的疾病。

Anthropogenic shifts in patterns of land use, habitat infringement and climate change increase the probability of viruses such as SARS-CoV-2, the causative agent of Covid-19, spilling over into humans and/or animals. In turn, increased urbanisation and global travel, the absence of herd immunity and poor preparedness can contribute to turn a localised epidemic into a global pandemic. However, not all viruses in nature appear to share the same propensity to spill over; some are restricted to individual hosts while others have a broad host-range and represent a much greater risk to humans and/or animals (livestock, pets and wildlife). Developing a better understanding of the factors that determine the 'zoonotic potential' of viruses is especially prescient as we look to improve pandemic preparedness in a post-Covid-19 landscape. One of the most important factors to understand in this context is how viral entry (the process whereby the virus attaches to and invades a host cell) correlates with zoonotic potential. In general viruses use specific receptors (proteins or sugars) to enter cells. These can vary between hosts, representing an important point of restriction that directly influences host-range and the potential for spill over. Developing an understanding of this relationship for whole taxonomic groups of viruses (genera or families) will help scientists and stakeholders to assess which viruses represent the greatest risk to humans and animals.Characterising virus receptor usage and host-range at a broad level is technically challenging. For instance, choosing viruses which accurately represent the overall diversity of their family is prone to bias, favouring established pathogens over those isolated in their natural bat or rodent reservoirs. To address this, we have developed and optimised a pipeline which utilises bioinformatic algorithms to unbiasedly select representative viruses. Within this project we will use this approach to characterise the zoonotic potential of the coronavirus and arenavirus families. All human coronaviruses, as well as many of the coronaviruses which infect our pets and livestock, are thought to have a zoonotic origin (bats or rodents). The same is true for the arenaviruses, with viruses like Lassa continually spilling over from their rodent reservoirs. As proof-of-principle we have already gathered this dataset for the morbillivirus genus, uncovering a number of interesting restrictions which may explain the narrower host range of this smaller group (genus) of viruses. Our experimental pipeline will proceed as follows: Once we have selected representative viruses, we will use a range of state-of-the-art techniques to quantify their receptor usage and host-range. Subsequently, we will use mutagenesis and protein-binding experiments to dissect the genetic determinants of this zoonotic potential. The assembled scientific research team has a longstanding interest in this area, with broad and overlapping interests in the morbillivirus, coronavirus and arenavirus families. Previously, we have identified amino acid changes in animal morbillivirus attachment proteins which convey tropism to human receptors, solved the structures of arenavirus attachment proteins and more recently examined the likely bat-origin of SARS-CoV-2. The information we generate in this project will be used to improve our pandemic preparedness, helping us to identify high risk pathogens with broad host-ranges (based on entry). Ultimately this information could be used to design new drugs and vaccines, hopefully preventing future disease in humans and animals.