科学家们如何能确认新冠病毒并非实验室产物？

原标题：科学家们如何能确认新冠病毒并非实验室产物？

从疫情爆发至今，虽然世界各地的科学家们都反复强调这种初次被发现的病毒来源于自然界，但是“新冠病毒是实验室产物”的阴谋论依然无休无止。

那么，科学家们到底是如何知道病毒并非来自实验室，而是起源于某种动物的呢？

威斯敏斯特大学一位寄生虫学与医学微生物学讲师，Polly Hayes，本周发表的一篇文章，引用多项研究对这个问题作出了解释。

The conspiracy theory that the novel coronavirus was created in a lab has been circulating since the beginning of the COVID-19 outbreak， although scientists from different countries have refuted it over and again and stressed the natural origin of the virus。

So how exactly do scientists know the virus SARS-CoV-2 originated from an animal， most likely a bat， and was not lab-made？

Polly Hayes， a lecturer in Parasitology and Medical Microbiology at the University of Westminster， explained the question in an article published on British website The Conversation earlier this week， citing multiple studies。

基因物质里并没有人为操纵的迹象

No signs of manipulation in the genetic material of SARS-CoV-2

Hayes指出，如果病毒来自实验室里的基因工程，那么它的基因序列数据一定存在人为操纵的迹象。

但是，新冠病毒的基因序列已被全世界的科学家公开分享了数千次，而且从未发现过这样的证据。

Hayes pointed out that if the virus had been genetically engineered in a lab， there would be signs of manipulation in the genome data。

This would include evidence of an existing viral sequence as the backbone for the new virus， and obvious targeted inserted （or deleted） genetic elements。

But the genetic sequence of SARS-CoV-2 has been publicly shared thousands of times by scientists all over the world， and no such evidence has ever been found。

She added that it is very unlikely that any techniques used to genetically engineer the virus would not leave a genetic signature， like specific identifiable pieces of DNA code。

从野生型的冠状病毒进化而来

SARS-CoV-2 evolved from a previous wild coronavirus

新冠病毒的基因序列与其他在蝙蝠和穿山甲身上发现的冠状病毒基因序列相似，不止如此，这些基因序列之间的差异显示了冠状病毒进化的自然模式。

The genome of SARS-CoV-2 is similar to that of other bat coronaviruses， as well as those of pangolins， all of which have a similar overall genomic architecture。

What‘s more， differences between the genomes of these coronaviruses show natural patterns typical of coronavirus evolution， which suggests that SARS-CoV-2 evolved from a previous wild coronavirus。

与武汉病毒研究所发现的蝙蝠病毒在进化上有显著差异

SARS-CoV-2 and a bat virus in Wuhan lab significantly different in evolutionary terms 

一些媒体报道说，新冠病毒可能来自武汉病毒研究所的研究人员发现的另一种已知的蝙蝠病毒（RaTG13），因为这两种病毒的基因序列相似性高达96%。但Hayes澄清说，从进化的角度来看，它们实际上有显著差异。

Some media reports have said that SARS-CoV-2 may come from another known bat virus （RaTG13） found by researchers at the Wuhan Institute of Virology， since the genomes of the two viruses were 96 percent similar to one another。

But Hayes clarified that in evolutionary terms， this actually makes them significantly different and the two have been shown to share a common ancestor。 That means RaGT13 is not an ancestor of SARS-CoV-2。 

与其他冠状病毒有相似特性

SARS-CoV-2 shared similar features with related coronaviruses

新型冠状病毒感染人体细胞的关键在于冠状病毒的刺突糖蛋白与人体ACE2蛋白的结合，但是，其他类似的冠状病毒都具有相似的特征。而新冠病毒的刺突糖蛋白与人体细胞的结合效率之高，通过基因工程无法达到，只有自然选择才能实现。

One of the key features that makes SARS-CoV-2 different from the other coronaviruses is a particular “spike” protein that binds well with another protein on the outside of human cells called ACE2。 This enables the virus to hook into and infect a variety of human cells。

However， other related coronaviruses do have similar features， providing evidence that they have evolved naturally rather than being artificially added in a lab。 

大多数传染病和所有已知的冠状病毒的来源是动物

The majority of infectious diseases and all known coronaviruses have animal origins

据估计，人类已知的传染病中有60%来源于动物，在所有新发或再发疾病中这个比例达到75%。

新冠病毒是人类发现的七种冠状病毒中最新的一种，而它们全部来自蝙蝠，小鼠或其他家畜。

An estimated 60 percent of known infectious diseases and 75 percent of all new， emerging， or re-emerging diseases in humans have animal origins。

SARS-CoV-2 is the newest of seven coronaviruses found in humans， all of which came from animals， either from bats， mice or domestic animals。

The mixing or “recombination” of distinct coronavirus genomes in nature is one of the mechanisms that bring about novel coronaviruses。 There is now further evidence that this process could be involved in the generation of SARS-CoV-2。

最有可能来自蝙蝠

SARS-CoV-2 most likely originated from bats

实际上，新冠病毒最有可能是由一种病毒变异体进化而来，该变异体无法长时间存活或潜伏于蝙蝠体内。

巧合的是，它进化出了入侵人类细胞的能力，然后可能是通过中间的动物宿主偶然获得了进入人类社会的途径，得以繁衍传播。

In fact， SARS-CoV-2 most likely evolved from a viral variant that couldn‘t survive for a long period of time or that persists at low levels in bats。

Coincidentally， it evolved the ability to invade human cells and accidentally found its way into humans， possibly by means of an intermediate animal host， where it then thrived。

Or an initially harmless form of the virus might have jumped directly into humans and then evolved to become harmful as it passed between people。

Bats were also the source of the viruses causing Ebola， rabies， Nipah and Hendra virus infections， Marburg virus disease， and strains of Influenza A virus。