Two new papers make the case robustly
兩篇新論文強有力地提出此真相
Mar 5th 2022
Two new papers provide more robust answers than heretofore available to three of the outstanding questions of the covid-19 pandemic: how, when and where sars-cov-2, the virus that caused it, first appeared in human beings.
兩篇新論文為2019冠狀病毒症(COVID-19：Coronavirus Disease-19)大流行病，三個未解決的問題，提供了比在此之前，可資獲得的更強有力答案：引發此症的第二型嚴重急性呼吸系統徵候群-冠狀病毒(SARS-CoV-2：Severe Acute Respiratory Syndrome Coronavirus-2)，何時、何處及如何首次出現在人類身上。
These papers, so-called preprints (meaning they have not yet gone through the formal process of peer review that precedes publication in a journal) were written by related teams of researchers from institutions around the world and posted to Zenodo, a repository for such documents.
此些所謂的預印本(意味著，它們尚未經過正式的同行評審程序，先於期刊上發表)論文，由來自世界各地機構之相關研究人員團隊，撰寫並張貼到此類文件的存儲庫Zenodo(根據歐洲OpenAIRE計劃開發，並由CERN運營的通用開放式存儲庫)中。
They conclude that, by November 2019, the virus was present in animals on sale at the Huanan Seafood Wholesale Market in Wuhan (pictured), whence it jumped to human hosts on two separate occasions a week or so apart.
他們得出的結論是，在2019年11月之前，該病毒已經存在於，中國武漢市華南海鮮批發市場出售的動物身上(如圖)，在間隔一星期左右的兩次不同時機中，從那裡躍進到人類宿主身上。
One paper, the lead authors of which are Michael Worobey at the University of Arizona and Kristian Andersen of Scripps Research, in San Diego, attempts to trace the first infections definitively to the Huanan market. The authors used three approaches.
一篇主要撰文人是，美國亞利桑那大學Michael Worobey，及位於聖地牙哥市斯克里普斯研究中心Kristian Andersen的論文，試圖將首批感染者明確地追溯到華南市場。此些撰文者們使用了三種方法。
First, by looking at the geographic distribution of early infections, they found that the market is in the region where the first covid-19 cases were most densely packed—a result that remains unchanged even when cases with no known link to the market are plotted.
第一種，藉由探究早期感染的地理分佈。他們發現，該市場位於第一批 covid-19病例最密集的地區。這是即標明了，與市場沒有已知關聯之病例，也保持不變的一種結果。
Second, they employed photographic evidence posted on Weibo, a Chinese social-media website, as well as contemporary accounts, to show that the market, which vends other goods besides seafood, was selling animals susceptible to the virus (a list that includes porcupines, marmots and raccoon dogs) prior to December 2019.
第二種，除了屬同一時期的記述之外，他們也採用了，張貼於微博(中國的一處社群媒體網站)上的照片證據來證實，該除了海鮮之外也販售其他商品的市場，在2019年12 之前，已在販售易感染該種病毒的動物(包括豪豬、土撥鼠及狸)。
Third, they analysed the distribution of almost 600 environmental samples taken from the market by the Chinese Centre for Disease Control and Prevention (CCDC) in January 2020, after it had been shut down by the authorities.
第三種，他們分析了，由中國疾病預防暨控制中心(CCDC)，在該市場已經被被當局關閉後，於2020年1月，由中國疾病預防暨控制中心(CCDC)，從該市場上採集，近600個環境樣本的分佈情況。
Combining this analysis with a recreation of the market layout, the authors showed that samples containing the virus were associated with stalls selling live animals, particularly in the market’s south-western corner.
結合此分析與該市場佈局的再現，此些撰文人表示，具有該種病毒的樣本，與出售活體動物的攤位有關，特別是在該市場的西南角。
The second paper, the lead author of which was Jonathan Pekar of the University of California, San Diego, examines the evolution of the virus in its earliest days in humans. At this time two forms, known as lineages a and b, predominated.
主要撰文人是美國加州大學聖地牙哥分校Jonathan Pekar的第二篇論文，探究了病毒在人類早期的演化過程。在此時，被通稱為a及b種系的的兩個類型，占優勢。
These differ in the nature of two particular nucleotide loci (links in the RNA chain that constitutes the virus’s genome), with lineage a having a structure identical to similar viruses found in bats.
對具有一種於蝙蝠中，被發現之類似病毒完全相同結構的種系a而言，它們在兩個特定核苷酸位點(此病毒基因體之RNA鏈中的環節)的性質上，有所不同。
This suggests that lineage a was the original form and lineage b a subsequent mutation. However, the first known human cases involved lineage b. To resolve this conundrum, the researchers analysed nearly 800 almost-complete viral genomes from samples taken before February 14th 2020, to identify the most likely evolutionary paths taken by the virus.
這暗示，種系a是原始形式，而種系b是一種隨後的突變。不過，已知最早的人類病例，涉及b種系。為了解決此難題，這些研究人員，在來自2020年2月14日之前採集的樣本中，分析了將近800個，幾乎完整的病毒基因體，來確認該種病毒最可能進行的演化途徑。
This analysis showed that, while both lineages were present in cases in the vicinity of the market, no samples contained either any transitional form or any shared common ancestor. It therefore seems likely that the lineages made independent leaps into human hosts: lineage b on or around November 25th 2019, and lineage a a week or so later.
此分析顯示，儘管於該市場附近的病例中，存在這兩個种系。不過，沒有樣本具有任何過度的形式或任何共有的共同原種。因此，這些種系似乎有可能，個自進行躍進到人類宿主上：也就是，種系b在2019年11月25 日或前後，而種系b在之後一星期左右。
Such multiple jumps from animals are common in coronaviruses. The viruses responsible for both the sars outbreak in 2002 and mers (Middle East respiratory syndrome), which appeared in 2012, are also thought to have started with multiple spillover events.
此類從動物的多次躍進，在冠狀病毒中很常見。於2002年，導致嚴重急性呼吸系統症候群(SARS：Severe Acute Respiratory Syndrome)爆發，及2012年出現之中東呼吸系統症候群(MERS：Middle East Respiratory Syndrome)的病毒，也被認為曾經以多次溢出事件開始。
All that the researchers felt they needed to make their case watertight was evidence of lineage a at the market. When they started work, all samples from there had contained only lineage b. This changed shortly before their papers went online, because of a detail buried in an unrelated preprint from a team at the CCDC.
此些研究人員認為，這一切，能使其病例無懈可擊，他們所需要的是，種系a存在於該市場的證據。當他們開始研究時，來自那裡的所有樣本僅具有種系b。在他們的論文上線前不久，因為一項隱匿於，來自英國劍橋晶體學數據中心(CCDC：Cambridge Crystallographic Data Centre)，一支團隊之不相關預印本中的細節，使情況發生了變化。
In a reanalysis of samples, this group discovered the first market-linked evidence of lineage a—on a discarded glove. “This really seals the deal,” says Dr Worobey. “Beyond all reasonable doubt we now know what happened.”
在對樣本的重新分析中，在被丟棄的一隻手套上，此團隊發現了，種系a首個與市場被聯繫在一起的證據。Worobey博士宣稱：「實際上，這確定了此事。」
Though the papers are preprints, their analysis has been praised by numerous independent researchers. Assuming they are indeed correct, rival hypotheses have a steep hill to climb. The most popular of these, as well as the most contentious, is that the virus escaped from a laboratory in Wuhan before triggering a “superspreader” event at the market.
雖然這些論文是預印本，不過他們的分析已經受到眾多獨立研究人員的讚譽。假設它們確實是正確的，那麼對立的假設就有一座陡峭的山要爬。其中最普遍，也最有爭議的是，這種病毒在該市場引發“超級傳播者”事件之前，從武漢市的一處實驗室逃逸。
The existence of two separate lineages at Huanan, says Dr Worobey, as well as the market’s central location in the density map of cases, suggests that such a lab leak would have had to have happened twice, while leaving no evidence yet discovered of the laboratory’s involvement on either occasion. That seems unlikely. Which animal species were responsible, though, remains to be determined.
Worobey表示，除了該市場於病例密度圖中的中心位置之外，於華南有兩個無關聯的種系，暗示這樣的實驗室洩漏，應該必需發生過兩次，而在任何一次都沒有遺留下，被發現之實驗室涉及的證據，那似乎不太可能。不過，是哪些動物物種導致的，仍有待確定。
網址：https://www.economist.com/science-and-technology/more-evidence-that-covid-19-started-in-a-market-not-a-laboratory/21807945?utm_content=ed-picks-article-link-1&etear=nl_special_1&utm_campaign=a.coronavirus-special-edition&utm_medium=email.internal-newsletter.np&utm_source=salesforce-marketing-cloud&utm_term=3/5/2022&utm_id=1069988
翻譯：許東榮
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