美国科学家：新冠病毒起源于武汉华南海鲜市场是错误观点

自新冠病毒感染的肺炎疫情发生以来，讨论病毒起源的声音不绝于耳，各种“阴谋论”也层出不穷，比如“病毒是实验室合成的”、“病毒起源于武汉华南海鲜市场”等。

The origin of the novel coronavirus has been widely discussed online since the outbreak. The conspiracy theories around it have also emerged endlessly.

此前已有科学家研究发现，新冠病毒是一种自然进化的产物。

Previous scientific studies have already suggested that SARS-CoV-2, the virus that caused COVID-19, originated through natural processes.

Screenshot from ABC News

杜兰大学医学院教授罗伯特·加里（Robert Garry）日前在接受美国广播公司（ABC）采访时也指出了“新冠病毒起源于武汉华南海鲜市场”是一个错误的观点。

In a recent interview with ABC news, Dr. Robert Garry, a professor at the Tulane University School of Medicine, once again pointed out that it's a misconception to believe the virus originated at a seafood market in Wuhan, China.

加里表示武汉华南海鲜市场虽然有一些病例，但它并不是病毒的源头。他和其他团队都分析发现了比海鲜市场更早的病毒起源。

他认为，新冠病毒表面蛋白的突变可能是触发这次病毒大流行的原因。但是在积累到目前情况之前，这种病毒的较弱版本已经在人群中传播了数年，甚至几十年。

"Our analyses, and others too, point to an earlier origin than that," Garry said. "There were definitely cases there, but that wasn't the origin of the virus."

According to Garry, the pandemic may be triggered by the mutation in surface proteins of the virus. But it's also possible that a less severe version of the illness was circulating through the population for years, perhaps even decades, before escalating to this point.

 Evidence for natural selection 

自然选择的证据 

在冠状病毒表面，有刺突蛋白形成的突起结构。冠状病毒也正是因为这些形态类似于树冠或日冕的刺突蛋白而得名。

在科学杂志《自然医学》刊发的一篇研究论文中，包括加里教授在内的美国科学家以及来自英国和澳大利亚的科学家研究了在入侵细胞过程中发挥作用的新冠病毒刺突蛋白的两个特征：抓住以及进入宿主细胞。

研究结果表明，新冠病毒刺突蛋白与人体细胞的结合效率之高，只有自然选择才能实现，靠人工操纵无法完成。

Coronaviruses are named for the crown-like spikes on their surface. In a study published on Nature Medicine, a group of scientists including Dr. Robert Garry, from the U.S., Britain, Australia analyzed two specific features of spike proteins of the virus, which are responsible for gripping and entering into the host cells.

The results show that the SARS-CoV-2 spike protein is optimized for binding to a molecular on the outside of human cells, so efficient that scientists concluded it was the result of natural selection and not a purposefully manipulated virus.

此外，科学家们还表示如果有人想要制造一种新的病毒，需要从一种已知的具有致病性的病毒主干中构建新病毒。

研究显示，新冠病毒的主干并非来源于已知的病毒主干。与其最相似的，是在蝙蝠和穿山甲体内发现的病毒主干。

Besides, if someone were trying to make a new virus, they have to engineer it from the backbone – molecular structure of a virus which is known to cause diseases in human, scientists said.

But what they found is that the SARS-CoV-2 backbone is not derived from any previously used virus backbone. The most closely resembled backbones were discovered in bats and pangolins.

斯克利普斯研究所免疫学和微生物学副教授克里斯蒂安·安德森（Kristian Andersen）在接受《每日科学》采访时表示：“刺突蛋白的突变以及不同的病毒主干这两个特征，排除了新冠病毒是‘实验室合成’的可能性。”

"These two features of the virus, the mutations in the RBD portion of the spike protein and its distinct backbone, rules out laboratory manipulation as a potential origin for SARS-CoV-2," Kristian Andersen, an associate professor of immunology and microbiology at Scripps Research and corresponding author of the paper told Science Daily.

 Two possible answers to the SARS-CoV-2 origin 

 关于新冠病毒起源两种可能的说法  

目前，科学家们还未能找到新冠病毒自然来源的确切答案。但对于新冠病毒的来源，他们给出了两种可能的情况：

• 一是病毒在动物宿主身上发生自然选择，然后从动物身上传播到人类身上

• 二是病毒从动物身上传播到人类身上后，在人类身上发生自然选择

What is exactly the natural origin blamed for COVID-19 has yet been worked out by global scientists. But they do propose two possible scenarios that can plausibly explain the origin of SARS-CoV-2, that is natural selection in an animal host before zoonotic transfer, and natural selection in humans following zoonotic transfer.

美国国立卫生研究院院长弗朗西斯·柯林斯（Francis Collins）认为，在第一种情况下，随着新冠病毒在蝙蝠或穿山甲等动物宿主中发生进化，其刺突蛋白也随之发生突变，以此来结合与人体中蛋白结构相似的分子并感染人体细胞。之前SARS和MERS病毒都是以这种形式暴发的。

在第二种情况下，新冠病毒在获得能够引发人类疾病的能力之前，就已经从动物传播到人类。经过不断的进化之后，它们最终获得了在人与人之间传播的能力，并具有了致病性。

According to Dr. Francis Collins, the director of the U.S. National Institutes of Health, in the first scenario, as the new coronavirus evolved in its natural hosts, possibly bats or pangolins, its spike proteins mutated to bind to molecules similar in structure to the human protein, thereby enabling it to infect human cells. Both the SARS and MERS outbreak followed this way.

The second scenario is that the new coronavirus crossed from animals into humans before it became capable of causing human disease. Then, as a result of natural evolution, the virus eventually gained the ability to spread human-to-human and cause diseases. 

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