【齐心抗疫】实验室竞相发现隐藏的冠状病毒感染

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Labs scramble to spot hidden coronavirus infections
实验室竞相发现隐藏的冠状病毒感染

By Jon Cohen, Kai KupferschmidtFeb. 11, 2020 , 5:15 PM

The seeming precision of the global tallies of cases and deaths caused by the novel coronavirus now spreading from Wuhan, China belies an alarming fact. The world is in the dark about the epidemic’s real scale and speed, because existing tests have limited powers—and testing is far too spotty. “We are underestimating how common this infection is,” cautions Jeremy Farrar, head of the Wellcome Trust.
目前，中国武汉爆发的新型冠状病毒在全球范围内导致的感染和死亡病例的统计数量看上去似乎相当精确，然而这却掩饰了一个令人担忧的事实。现有的检测能力有限并且检测的质量也参差不齐，因此世界各国对此次传染病实际的规模和传染速度知之甚少。惠康基金会负责人杰里米·法勒提醒道：“我们低估了此次的传染规模。”

Within days of Chinese researchers releasing the sequence of the virus on 11 January, scientists developed tests capable of detecting genetic sequences that distinguish the new agent from other coronaviruses circulating in humans. By 28 January, China’s National Medical Products Administration had approved diagnostic test kits from five companies. It was an astonishing pace for the response to a pathogen never seen before—and yet it was only a beginning.
中国的科研人员在1月11日公布了新冠病毒的基因序列，几天之内，科学家们就进行了能够检测基因序列的测试，这些序列能够区别新冠病毒和在人类间流行的其他冠状病毒。截至1月28日，中国国家药品监督管理局已审核通过五家企业的诊断试剂盒。尽管相关工作刚刚起步，但是中国应对这种前所未见的病原体，其速度之快令人震惊。

Today, there aren’t nearly enough test kits available to keep up with the skyrocketing case numbers, and some parts of the world may lack enough trained laboratory staff to apply them. And because the genetic tests look for snippets of viral genetic material in nose and throat swabs or fluid collected from the lung, they only work when somebody has an active infection. Scientists are still scrambling to detect antibodies against the virus in the blood, which could help find people who had an infection and recovered.
目前，几乎没有足够的试剂盒能够用来应对激增的病例，而且部分地区可能还缺乏会使用试剂盒的专业人员。而且，基因检测是用棉签在鼻腔和喉咙收集样本或者收集来自肺部的液体进行基因片段的检测，因此，基因检测只有在人出现明显症状时才会起作用。科学家们仍在努力从血液中检测病毒抗体，这也许可以帮助鉴别曾经感染并已康复的人群。


Hubei province, which includes Wuhan, accounts for 75% of the more than 43,000 confirmed cases of COVID-19, as the World Health Organization (WHO) named the new disease on 11 February. (A study group of the International Committee on Taxonomy of Viruses christened the novel virus severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2, the same day.)
世界卫生组织（WHO）于2月11日给这种新型疾病命名，此时，在43000多确诊感染新型冠状病毒肺炎（COVID-19）的病例中，包括武汉在内的湖北省占比75%。[同日，国际病毒分类委员会一研究小组将这一新型病毒命名为“SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2)”。]。

But many news stories have reported shortages of diagnostics in Hubei. “They’re overwhelmed,” says epidemiologist Ian Lipkin of Columbia University, who recently returned from China and is in self-imposed quarantine at home. Testing in Hubei has focused on people sick enough to seek medical care, so tens of thousands of milder cases may not have been picked up. Outside Hubei, testing is even patchier. “What’s the full picture in the other parts of China?” asks Keiji Fukuda, an epidemiologist at the University of Hong Kong who previously led outbreak responses at WHO.
然而，许多新闻报道都表明，湖北的试剂盒严重短缺。哥伦比亚大学流行病学家伊恩·利普金刚从中国回国，目前自愿在家中隔离。他表示：“人们不堪重负。”在湖北，需要医疗救助的重症患者才会得到检测，因此，成千上万的轻症患者可能并没有得到治疗。湖北之外的检测更加零碎。香港大学流行病学家福田敬二先前在世界卫生组织领导应对疫情爆发，他问道：“中国其他省份的整体情况到底如何？”

Similar questions loom elsewhere. No cases have been confirmed in Africa, but there has been little testing. Initially, only two African labs were capable of detecting the virus, says John Nkengasong, who heads the African Centres for Disease Control and Prevention: “If this virus had shown up in Africa in December, or early January, it would have been devastating.” The continent is better prepared since a workshop in Dakar, Senegal, last week where lab workers from 15 African countries were taught how to use one of the new viral tests, which are based on the polymerase chain reaction assay, Nkengasong says. (Another workshop will follow next week.) Given that the virus has spread so widely, however, Farrar says he would be “very surprised” if it isn’t already in Africa.
其他地区可能存在类似的问题。尽管非洲暂无确诊病例，但是目前检测能力十分有限。起初，非洲只有两个实验室可以进行病毒检测工作，非洲疾病预防控制中心负责人约翰·肯加松（John Nkengasong）说道。他表示：“如果新冠病毒在12月或1月初就已经传到了非洲，这将是毁灭性的灾难。”他还表示，目前非洲已加强应对，上周在塞内加尔的达喀尔市举行的研讨会上，来自非洲15个国家的研究人员，学习了一种基于聚合酶链式反应的病毒检测方法。（下周将会举行另一场研讨会。）然而，鉴于病毒肆虐甚广，法勒表示，如果非洲仍无新冠病例，他会感到“十分意外”。

Even in the United States, test kits are in short supply. Regulations require that the U.S. Centers for Disease Control and Prevention (CDC) supply all tests, but that agency only began to do so on 5 February and has shipped a mere 200 kits so far, each able to do at most 800 tests. U.S. officials still don’t test most people flying in from China but focus on those who have symptoms of the disease. “We’re not able to do the surveillance that we would want to do,” says Wendi Kuhnert-Tallman, who heads CDC’s laboratory task force for the virus.
即使是在美国，检测试剂盒也供不应求。按照规定，美国疾病预防控制中心应该提供足够的试剂盒，但该机构2月5日才开始这么做，目前也仅调配了200个试剂盒，每个试剂盒最多能做800次检测。美方仍不会对大部分来自中国的旅客进行检测，而只是关注那些出现这种疾病症状的人。“试剂盒不足，我们无法按照要求进行检测。”美国疾控中心病毒实验室工作组负责人万迪·库纳特·托曼（Wendi Kuhnert-Tallman）如是说。
Many labs, including Lipkin’s, are racing to develop antibody tests, which will do little to diagnose acute cases—it can take weeks for that immune response to kick in—but could help clarify mystifying questions about SARS-CoV-2’s spread.
包括利普金实验室在内的多个实验室正竞相研发抗体测试。因免疫反应要花数周的时间才能发挥作用，该测试对诊断急性病例几乎毫无帮助。但可能有助于阐明有关SARS-CoV-2传播的谜题。
Such tests use a surface protein of the virus—or, in Lipkin’s case, an array of peptides—to capture antibodies specific to the virus in the blood. But a new test has to be validated using blood from infected people. CDC prefers to wait for 3 weeks after a person becomes ill to let antibody levels build, Kuhnert-Tallman says. So far, “We have one single case in the U.S. that has reached the 21-day mark.” A team led by Marion Koopmans of Erasmus Medical Center in Rotterdam, the Netherlands, expects to launch studies of its first version of an antibody test next week. It could be several more weeks before a company develops antibody kits and can churn them out by the thousands.
这种测试要用到病毒的表面蛋白，利普金实验室用的是一组肽，来捕获血液中针对病毒的抗体。但新的检测方法必须用感染者的血液来验证。库纳特·托曼说，疾病防治中心更倾向于在患者发病后等待3周，让抗体水平自行升高。目前，“美国有一个病例已经持续了21天。”荷兰鹿特丹伊拉斯姆斯医疗中心的玛丽昂·科普曼斯领导了一个研究小组，该小组预计下周将对其首个版本的抗体进行研究。可能要数周才有企业研发出抗体试剂盒并大批量生产。
Antibody tests might help pinpoint where and when this outbreak began, and which animal was the original source of the virus: Researchers could search for evidence of infection in stored samples of human blood or in animals that might be a natural reservoir of the virus. But the “most useful application is to screen different age groups of humans,” Koopmans says, to determine how many people become infected with few or no symptoms. If indeed scientists discover many mild cases, the rates of severe disease (estimated at about 20%) and death (2%) among infected people will plummet—which would finally be a bit of good news.
抗体测试可能有助于查明疫情开始的时间和地点，以及哪种动物是病毒的原始宿主：研究人员可以在储存的人类血液样本，或可能天然携带病毒的动物身上寻找传染病的证据。但科普斯曼说，“最可行的办法是对不同年龄段的人进行筛查”，以确定有多少人感染却症状轻微或无症状。如果科学家们确实发现了很多轻微症状的病例，那么严重病例率（估计约20%）和感染死亡率（约2%）就会直线下降，这最终可能是一个好消息。

原文链接：https://www.sciencemag.org/news/ ... onavirus-infections

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