As the new coronavirus continues to spread around the globe, researchers say the virus is changing its genetic makeup slightly. 

隨著這種新型冠狀病毒繼續(xù)在全球范圍內傳播，研究人員表示，這種病毒的基因構成正在發(fā)生輕微的改變。

But does that mean it is becoming more dangerous to humans? 

但這是否意味著它對人類的危害越來越大了呢?

And what would the impact be on any future vaccines?

這對未來的疫苗又有什么影響呢?

"In the literal sense of 'is it changing genetically,' the answer is absolutely yes," says Marc Lipsitch, an infectious disease epidemiologist at Harvard University. 

哈佛大學傳染病流行病學家馬克·利普西奇表示:“從字面意義上講，'這是否改變了基因呢’，答案絕對是肯定的。

"What is in question is whether there's been any change that's important to the course of disease or the transmissibility or other things that we as humans care about."

“值得討論的是，是否有任何變化關乎于疾病的進程，傳播能力或其他我們人類關心的事情呢?！?/p>

So far, "there is no credible evidence of a change in the biology of the virus either for better or for worse," says Lipsitch.

到目前為止，“還沒有可靠的證據表明這種病毒的生物學變化是好是壞，”利普西奇說。

Coronaviruses — like all viruses — change small parts of their genetic code all the time.

冠狀病毒和所有病毒一樣，總是在改變著其遺傳密碼的一小部分。

"Viruses mutate naturally as part of their life cycle," says Ewan Harrison, scientific project manager for the COVID-19 Genomics UK Consortium, a new project that tracks the virus in the United Kingdom.

“病毒自然變異是它們生命周期的一部分，”COVID-19基因組英國聯(lián)盟的科學項目經理伊萬·哈里森說，COVID-19基因組英國聯(lián)盟是一個跟蹤英國病毒的新項目。

Like flu and measles, the coronavirus is an RNA virus. 

與流感和麻疹一樣，冠狀病毒是一種RNA病毒。

It's a microscopic package of genetic instructions bundled in a protein shell. 

它是包裹著蛋白質外殼的基因指令的微小包裹。

When a virus infects a person, the string of genetic instructions enables the virus to spread by telling it how to replicate once it enters a cell. 

當一種病毒感染了一個人之后，一系列的遺傳指令通過告訴病毒一旦進入細胞如何復制，從而使病毒得以傳播。

The virus makes copies of itself and pushes them out to other cells in the body.

病毒會復制自身，并將它們推向體內的其他細胞。

Infectious doses of the virus can be coughed out in droplets and inhaled by others.

感染劑量的病毒可以通過飛沫咳出，也可以被其他人吸入。

Inevitably, viruses "make mistakes in their genomes" as they copy themselves, says Harrison. 

哈里森說，病毒在復制自己的時候不可避免地“會在基因組中犯錯誤”。

Those changes can accumulate and carry over to future copies of the virus. 

這些變化會積累并延續(xù)到病毒的未來副本。

Researchers are using these small, cumulative changes to trace the pathway of the virus through groups of people.

研究人員正在利用這些微小的、累積的變化來追蹤病毒在人群中的傳播途徑。

So far, researchers who are tracking the genetic changes in SARS-CoV-2 — the official name for the coronavirus — say it seems relatively stable. 

到目前為止，追蹤SARS-CoV-2(冠狀病毒的官方名稱)基因變化的研究人員說，這種病毒似乎相對穩(wěn)定。

It acquires about two mutations a month during this process of spread, Harrison says — about one-third to one-half the rate of the flu.

哈里森說，在傳播的過程中，病毒一個月大約產生兩種變異，速率大約是流感的三分之一到二分之一。

Coronaviruses differ from flu viruses in another key way that reduces the number of mutations. 

冠狀病毒與流感病毒的另一個關鍵區(qū)別在于它可以減少突變的數量。

They proofread their own genomes when they copy themselves, cutting out things that don't seem right. 

當他們復制自己的時候，他們會校對自己的基因組，刪除那些看起來不正確的東西。

"They maintain this ability to keep their genome pretty much intact," says Vineet Menachery, a virologist at the University of Texas Medical Branch. 

德克薩斯大學醫(yī)學分部的病毒學家文尼特·馬娜切瑞說:“它們保持這種能力，以保持他們的基因組基本完整?！?/p>

"The mutations that they incorporate are relatively rare."

“它們發(fā)生結合的突變相對少見?！?/p>

This added proofreading function means that coronaviruses are also one of the largest RNA viruses. 

這種附加的校對功能意味著冠狀病毒也是最大的RNA病毒之一。

They're about 30,000 nucleotides long — double the size of flu viruses. 

它們大約有3萬個核苷酸長，是流感病毒的兩倍。

But at 125 nanometers wide, they're still microscopic; 800 of them could fit in the width of a human hair.

但在125納米寬時，它們仍然是微觀的;800個病毒才相當于一根頭發(fā)絲的寬度。

Nonetheless, their relatively larger size means "they have a lot more tools in their tool belt" compared with other RNA viruses, says Menachery — in other words, more capability of fighting off a host's immune system and making copies of themselves.

盡管如此，Menachery說，與其他RNA病毒相比，它們相對較大的體積意味著“它們的工具庫帶里有更多的工具”——換句話說，它們有更強的能力擊退宿主的免疫系統(tǒng)并復制自己。

Researchers are on alert for changes that might affect how the coronavirus behaves in humans. 

研究人員對可能影響人類冠狀病毒行為的變化保持著警惕。

For instance, if the coronavirus developed ways to block parts of our immune system, it could hide out in our bodies and establish itself better. 

例如，如果冠狀病毒能夠阻斷我們免疫系統(tǒng)的某些部分，它就能隱藏在我們的身體里，更好地生存下去。

If it evolved to bind more strongly to human cells, it could enter them more efficiently and replicate more quickly.

如果它在進化過程中更強地與人類細胞結合，它就能更有效地進入人類細胞，并更快地進行復制。

But it's not as if the coronavirus needs to become more potent to survive and thrive. 

但這并不是說冠狀病毒需要變得更強才能生存和繁衍。

It's already replicating itself around the world very successfully, says Justin Bahl, an evolutionary biologist at the University of Georgia. 

佐治亞大學的進化生物學家賈斯汀·巴爾說，它已經非常成功地在世界各地復制了自己。

"The viruses themselves are not actually under much pressure to change."

“實際上，病毒本身并沒有面臨太多改變的壓力?！?/p>

Selective pressures could come from introducing treatments and vaccines that are effective against a narrow group of coronavirus strains. 

選擇性壓力可能來自于引進對一小群冠狀病毒株有效的治療方法和疫苗。

If that happens, strains that aren't targeted by these measures would likely proliferate.

如果發(fā)生這種情況，那么這些措施沒有針對的那些菌株可能就會擴散。

The small genetic changes that researchers have observed so far don't appear to be changing the function of the virus. 

到目前為止，研究人員觀察到的微小的基因變化似乎并沒有改變病毒的功能。

"I don't think we're going to see major new traits, but I do think that we're going to see different variants emerge in the population," says Bahl.

“我認為我們不會看到主要的新特征，但我確實認為我們會在人群中看到不同的變異，”巴爾說。

And that slower rate of change is potentially good news for treatments and vaccines. 

對于治療和疫苗來說，變化的速度變慢可能是個好消息。

Researchers think that once a person gains immunity against SARS-CoV-2, either by recovering from an infection or by getting a future vaccine, they will likely be protected against the strains in circulation for "years rather than months," predicts Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center, in an assessment shared on Twitter.

研究人員認為,一個人一旦對SARS-CoV-2獲得免疫力,比如從感染中恢復或接種了未來的疫苗,他們可能會在未來幾年而不是幾個月內，免受病毒傳染的壓力,”特雷弗貝德福德預言說,他是弗雷德哈欽森癌癥研究中心的進化生物學家,在評估在推特上分享道。

Projects such as the COVID-19 Genomics UK Consortium will use these genetic drifts to track the path of the virus and figure out if there are hospitals or community hubs that are hot spots for contagion, according to Harrison. 

哈里森說，COVID-19基因組英國聯(lián)盟等項目將利用這些遺傳漂移來跟蹤病毒的路徑，并查明是否有醫(yī)院或社區(qū)中心是傳染的熱點。

This will give public health officials a sense of where and how the virus is being transmitted now.

這將使公共衛(wèi)生官員了解到目前病毒的傳播地點和方式。

Will the coronavirus surge when schools reopen? 

校開學后新冠病毒會激增嗎?

Will new strains emerge that develop resistance to drugs or vaccines that are introduced? 

會不會出現(xiàn)對藥物或疫苗產生耐藥性的新毒株呢?

To answer such questions, Harrison says, the long-term plan is to track the virus in real time — and see how it changes as it spreads.

哈里森說，要回答這些問題，長期的計劃就是實時追蹤病毒，并觀察病毒在傳播過程中如何變化。