中国新型病毒：科学家们提出的五个问题
【慕联导读】
New China virus: Five questions scientists are asking中国新型病毒：科学家们提出的五个问题
研究人员正竞相寻找更多有关在亚洲及其他地区传播的冠状病毒的流行病学和遗传序列的信息。
Health authorities around the world are worried about an outbreak of a mysterious virus that originated in Wuhan, China, last month. Officials there have confirmed more than 500 cases of the infection, which causes a respiratory illness, and 17 deaths. Several cases have been spotted elsewhere in Asia and one in the United States.
上个月，全世界的卫生部门都对一种起源于中国武汉的神秘病毒的爆发感到担忧。那里的官员已经确认了500多例感染病例，导致呼吸道疾病，并有17人死亡。在亚洲其他地方和美国都发现了几起案件。
Researchers are racing to learn more about the virus and to discover whether it has the potential to cause an outbreak similar to the 2002–03 epidemic of severe acute respiratory syndrome (SARS), which emerged in southern China and killed 774 people in 37 countries. Both are members of a large virus family, called coronaviruses, that also includes those responsible for the common cold.
研究人员正在竞相进一步了解该病毒，并发现其是否有可能引起类似于2002-03年严重急性呼吸道综合症（SARS）流行的暴发。该病在中国南部出现，在37个国家死亡774人。两者都是一个很大的病毒家族的成员，冠状病毒，也包括那些引起普通感冒的病毒。
Efforts to understand the outbreak are especially crucial, because mass travel from Friday for the Chinese New Year holiday could spread the virus farther and faster.
了解疫情的爆发尤其重要，因为从周五开始农历新年假期的大规模旅行可能会进一步传播该病毒。
How does the virus spread?
The most urgent question surrounding the outbreak is determining how it spreads. Chinese authorities have confirmed that some cases have been caused by transmission between humans, but it’s still unclear whether this can happen routinely.
病毒如何传播？
围绕此次疫情最紧迫的问题是确定它如何传播。中国当局已经证实，一些病例是由人际传播引起的，但目前还不清楚这种情况是否会经常发生。
“What’s critical to understand is whether that’s occurring at a rate and with a level of efficiency which would sustain a human epidemic,” says Neil Ferguson, a mathematical epidemiologist at Imperial College London. Monitoring the rate at which new cases appear, and when symptoms began for each case, should tell scientists how easily the virus can pass between humans and whether the outbreak has the potential to persist.
伦敦帝国理工学院的数学流行病学家尼尔·弗格森说：“要理解的关键是，这种情况是否以一定的速度和一定的水平发生，从而能够维持人类的流行病。” 监测新病例的发生率以及每种病例的症状开始的时间，应该告诉科学家该病毒在人与人之间的传播容易程度，以及这种爆发是否可能持续存在。
How deadly is the virus?
High rates of pneumonia among the first people infected had many researchers worried that the Wuhan virus was especially pernicious. Those concerns have receded slightly, as more mild cases turn up. With at least 17 deaths in more than 500 cases, the virus does not seem to be as deadly as SARS — which killed an estimated 11% of the people it infected. But “It’s too early to be sanguine about the severity,” Ferguson says.
病毒有多致命？
在首批感染者中，肺炎的高发病率使许多研究人员担心武汉病毒特别有害。随着案件数量的增加，这些担忧有所减轻。该病毒在500余例病例中至少有17例死亡，似乎不像SARS那样致命，该病毒杀死了大约11％的感染者。但是弗格森说：“现在就确定严重程度还为时过早。”
Where did the virus come from?
Authorities are working on the theory that the virus originated in an unidentified animal or animals, and then spread to humans at a large animal and seafood market in Wuhan. Identifying the animal source of the virus could help to control the current outbreak and gauge its threat — and potentially prevent future epidemics, say researchers. Genetic sequencing suggests that the Wuhan virus is related to coronaviruses that circulate in bats, including SARS and its close relatives. But other mammals can transmit these viruses — SARS was probably spread to humans by civet cats.
病毒是从哪里来的？
有关部门正在研究这一理论，即病毒起源于一种或多种不明动物，然后在武汉的一个大型动物和海鲜市场传播给人类。研究人员说，确定病毒的动物来源可能有助于控制目前的疫情并评估其威胁，并有可能预防未来的流行病。基因测序表明，武汉病毒与在蝙蝠中传播的冠状病毒有关，包括SARS及其近亲。但是其他哺乳动物可以传播这些病毒——SARS可能是由果子狸传播给人类的。
The live-seafood market where the outbreak seems to have originated — now closed — also sells wild animals. Tracing other cases to the market could help to identify the source, as could tests of animals from the market, or containers and cages, for viral genetic material, says Ben Cowling, an epidemiologist at the University of Hong Kong.
似乎已爆发疫情的活海鲜市场（现已关闭）也出售野生动物。香港大学的流行病学家本·考林（Ben Cowling）说，追踪市场上的其他病例可能有助于确定病毒的来源，对市场上的动物、容器和笼子进行病毒遗传物质的检测也可能有助于确定来源。
What can we learn from the virus’s genetic sequence?
Genetic sequencing of the Wuhan coronavirus offers clues to its origins and spread. Laboratories in China and Thailand have sequenced the genomes of at least 19 strains found in infected people and have made them publicly available. That’s “pretty remarkable, given that we’re two weeks after work has begun,” says Trevor Bedford, an evolutionary geneticist at Fred Hutchinson Cancer Research Center in Seattle, Washington, who is analysing the sequences as they come in. “People are extremely fast and excellent about data sharing,” Bedford adds.
我们可以从病毒的遗传序列中了解到什么？
武汉冠状病毒的基因测序提供了其起源和传播的线索。中国和泰国的实验室已经对感染者中发现的至少19种菌株的基因组进行了测序，并将其公开提供。华盛顿弗雷德·哈钦森癌症研究中心的进化遗传学家特雷弗·贝德福德（Trevor Bedford）说：“鉴于我们的工作已经开始了两周，这真是太了不起了。” Bedford补充说：“人们在数据共享方面非常快速和出色。”
Bedford says that the most striking thing about the sequences is how similar they are to one another. “There’s very little diversity. I expected to see more and I think other people did as well.” The lack of genetic diversity suggests that the common ancestor of the different human strains emerged in November or December and has spread rapidly, and hasn’t gained many mutations. Those it has gained tend to be distinct for each virus sequence. However, Bedford adds, the genomes don’t yet indicate whether the rapid expansion of the virus occurred in humans or in an animal reservoir. Evolutionary geneticist Andrew Rambaut at the University of Edinburgh, UK, posted an analysis on 20 January that came to a similar conclusion.
贝德福德说，这些序列最惊人的地方是它们彼此之间的相似性。“这里几乎没有多样性。我希望看到更多，我想其他人也一样。“基因多样性的缺乏表明，不同人类品系的共同祖先在11月或12月出现，并迅速传播，没有出现很多突变。它所获得的病毒序列往往是不同的。然而，贝德福德补充说，基因组尚不能表明病毒的迅速扩散是发生在人类身上还是动物体内。英国爱丁堡大学的进化遗传学家Andrew Rambaut在1月20日发表了一篇分析文章，得出了类似的结论。
Bedford says that, with further virus sequences, it might be possible to find out whether most cases are caused by repeated spillover of the virus from animals into humans, with limited human-to-human transmission, or whether the virus spread to a small number of humans and most cases are now being caused by secondary human-to-human transmission. “I think that would be the big epidemiological goal for everyone at the moment,” he says. Genetic information from the animal or animals that transmitted the virus to humans would also be helpful in identifying the extent of human-to-human transmission, Bedford adds.
贝德福德说，随着病毒序列的进一步发展，也许有可能发现大多数情况是由于病毒从动物向人的反复扩散，人与人之间的传播受限而引起的，还是该病毒是否传播了少量人口，大多数情况是由人与人之间的二次传播引起的。他说：“我认为这将是目前每个人的主要流行病学目标。”贝德福德补充说，来自将病毒传播给人类的一种或多种动物的遗传信息也将有助于确定人与人之间的传播程度。
Such sequences, he says, could also identify any genetic changes that might have helped the virus make the jump from animals to humans. And if the outbreak drags on because of extensive human-to-human transmission, Bedford and other geneticists will be looking for signs that the virus has gained further mutations enabling it to spread more efficiently in humans.
他说，这样的序列也可以识别任何可能帮助病毒从动物转移到人类的基因变化。如果这次疫情因为广泛的人际传播而拖延下去，贝德福德和其他遗传学家将寻找病毒已经获得进一步变异的迹象，使其能够更有效地在人类中传播。
Bedford cautions that these conclusions are preliminary, because so few data are available. “Adding a few key samples can change the story significantly,” he says.
贝德福德警告说，这些结论只是初步的，因为很少有可用数据。他说：“添加一些关键样本可以极大地改变情况。”
Can a drug be developed to treat the coronavirus?
No drugs have been shown to be effective in treating SARS or other coronavirus infections in humans, and no vaccines aimed at preventing these infections have been licensed.
可以开发治疗冠状病毒的药物吗？
尚无药物可有效治疗人的SARS或其他冠状病毒感染，也未获得任何旨在预防这些感染的疫苗的许可。
A team at China’s National Engineering Research Center for the Emergence Drugs in Beijing is working on finding therapies that would work by blocking the receptor on human cells that the virus latches on to and uses to infect. A comparison of the SARS and new China virus sequences, published on 16 January, found that they bind to the same receptor. The team is hoping to revive efforts to develop treatments for SARS and adapt them in a bid to make a drug could work against the latest virus.
位于北京的中国国家紧急药物工程研究中心的一个小组正在寻找治疗方法，阻断病毒附着并用来感染的人体细胞上的受体。1月16日发表的对SARS和新中国病毒序列的比较发现，它们与同一受体结合。该研究小组希望恢复对SARS治疗方法的研发工作，并对其进行调整，以研制出一种可以对抗这种最新病毒的药物。
来源：Nature《自然》www.nature.com/articles/d41586-020-00166-6
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