新冠病毒可能已經在人類中傳播多年大綱

As COVID-19 has hitchhiked around the globe, causing lockdowns, pneumonia and fear, scientists have been racing to determine where the SARS-CoV-2 coronavirus has come from.

新冠病毒在全球傳播，導致多地封城，並引發了肺炎和恐慌，科學家們一直在努力確定新冠病毒的來源。

While we don't have all the answers yet - including whether it came from an animal reservoir - a new analysis has definitively put to rest the conspiracies that claim it's a lab-made disease.

雖然我們還沒有弄清所有問題，如病毒是否來自動物宿主，但新的分析結果的確終結了病毒來自於實驗室的說法。

The study raises some interesting possibilities regarding the origin of the new coronavirus. One of the scenarios suggests the virus may have been circulating harmlessly in human populations for quite a while before it became the pandemic that's now stopped the world in its tracks.

這項研究針對新冠病毒的來源提出了幾種有趣的可能性。其中一種設想是病毒可能已經在人類中無害傳播了很久，然後才發展成了疫情，導致世界停滯不前。

"It is possible that a progenitor of SARS-CoV-2 jumped into humans, acquiring [new genomic features] through adaptation during undetected human-to-human transmission," the team from the US, UK and Australia writes in the study.

這個來自美國、英國和澳大利亞的團隊在研究中寫道：“可能最初的新冠病毒進入人體以後，在未被發現的人際傳播中爲了適應人體環境獲得了‘新的基因組特徵’。”

"Once acquired, these adaptations would enable the pandemic to take off and produce a sufficiently large cluster of cases."

“一旦獲得了‘新的基因組特徵’，就會爆發疫情，產生一個足夠大的病例羣。”

The researchers analysed genomic data available from SARS-CoV-2 and other similar coronaviruses, showing that the receptor-binding domain (RBD) sections of SARS-CoV-2 spike proteins were so effective at binding to human cells, they had to be caused by natural selection.

研究人員分析了從新冠病毒和其他類似的冠狀病毒中獲取的基因組數據，發現新冠病毒刺突蛋白的受體結合區和人體細胞能有效結合，這些都要通過自然選擇實現。

"By comparing the available genome sequence data for known coronavirus strains, we can firmly determine that SARS-CoV-2 originated through natural processes," said one of the researchers, immunologist Kristian Andersen at Scripps Research.

參與這項研究的斯克利普斯研究所的免疫學家Kristian Andersen說：“通過比較已知冠狀病毒毒株可用的基因組序列數據，我們可以確定新冠病毒源於自然過程。”

"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."

“這個病毒的兩個特點，刺突蛋白的受體結合區和它的主幹的突變，都排除了實驗室操作是新冠病毒潛在來源的可能性。”