What is a coronavirus? - Elizabeth Cox

Translator: 潘 可儿 Reviewer: Chak Lam Wan

For almost a decade, scientists chased the source of a deadly new virus

將近十年嚟，科學家一直喺中國

最高嘅山同最偏僻嘅山窿

through China’s tallest mountains and most isolated caverns.

尋找著一種致命嘅新型病毒

They finally found it here: in the bats of Shitou Cave.

佢哋最終喺雲南洞穴嘅蝙蝠身上搵到

The virus in question was a coronavirus

呢種未知嘅病毒係一種冠狀病毒

that caused an epidemic of severe acute respiratory syndrome,

佢引發咗 2003 年 嚴重急性呼吸綜合征

or SARS, in 2003.

即係沙士

Coronaviruses are a group of viruses

冠狀病毒係一類

covered in little protein spikes that look like a crown—

由細小蛋白刺突包裹嘅病毒 佢睇起身好似一個皇冠

or "corona" in Latin.

用拉丁語講就係 corona

There are hundreds of known coronaviruses.

已知嘅冠狀病毒有幾百種

Seven of them infect humans, and can cause disease.

其中有七種會感染人類、令人病

The coronavirus SARS-CoV causes SARS, MERS-CoV causes MERS,

譬如話，沙士冠狀病毒會引發沙士

中東呼吸綜合症冠狀病毒 會引發中東呼吸綜合症

and SARS-CoV-2 causes the disease COVID-19.

新冠病毒就會引發新冠肺炎

Of the seven human coronaviruses, four cause colds,

喺七種人類冠狀病毒之中 四種會引致感冒

mild, highly contagious infections of the nose and throat.

鼻、喉嚨會受到輕度而高傳染性嘅感染

Two infect the lungs, and cause much more severe illnesses.

兩種會感染肺部 並引發更嚴重嘅疾病

The seventh, which causes COVID-19, has features of each:

而第七種，即新冠病毒 有頭六種嘅特徵

it spreads easily, but can severely impact the lungs.

佢好容易傳播 嚴重影響肺部功能

When an infected person coughs, droplets containing the virus spray out.

一個病毒感染者一旦咳嗽 含有病毒嘅飛沫就開始散播

The virus can infect a new person when the droplets enter their nose or mouth.

當飛沫入咗鼻或者嘴 病毒就傳染畀另一個人

Coronaviruses transmit best in enclosed spaces,

當好多人都喺同一個密閉空間嗰時

where people are close together.

冠狀病毒就係傳播得最犀利

Cold weather keeps their delicate casing from drying out,

而天氣寒冷，令冠狀病毒 脆弱嘅外殼免於脫水

enabling the virus to survive for longer between hosts,

令佢哋喺宿主之間生存得更耐

while UV exposure from sunlight may damage it.

陽光中嘅紫外線 或者可以破壞脆弱嘅外殼

These seasonal variations matter more for established viruses.

雖然季節變化對已知病毒嘅影響大

But because no one is yet immune to a new virus,

但由於冇人對呢種新病毒有免疫

it has so many potential hosts that it doesn’t need ideal conditions to spread.

所以佢唔需要理想條件 就可以感染好多潛在宿主

In the body, the protein spikes embed in the host’s cells and fuse with them—

喺人體之中，蛋白刺突嵌入 宿主細胞，並同佢結合

enabling the virus to hijack the host cell’s machinery

因此，病毒可以綁架 成個宿主細胞機制

to replicate its own genes.

要挾宿主細胞複製病毒嘅基因

Coronaviruses store their genes on RNA.

冠狀病毒將佢哋嘅基因儲存喺 RNA

All viruses are either RNA viruses or DNA viruses.

所有病毒都可以分為 RNA 病毒 或者 DNA 病毒

RNA viruses tend to be smaller, with fewer genes,

RNA 病毒一般都比較細 攜帶較少嘅基因

meaning they infect many hosts and replicate quickly in those hosts.

即佢哋可以感染好多宿主 仲可以喺宿主體內快速複製

In general, RNA viruses don’t have a proofreading mechanism,

一般嚟講，RNA 病毒 都係冇校對機制嘅

whereas DNA viruses do.

而 DNA 病毒就有

So when an RNA virus replicates,

所以當一個 RNA 病毒複製緊

it’s much more likely to have mistakes called mutations.

基因變異就更頻繁噉發生

Many of these mutations are useless or even harmful.

呢啲變異好多都係冇用 甚至係有害

But some make the virus better suited for certain environments—

但有啲變異可以令病毒 更加適應到某啲環境

like a new host species.

譬如係一種新嘅宿主物種

Epidemics often occur when a virus jumps from animals to humans.

當一種病毒從動物傳播到人類身上 流行病就會發生啦

This is true of the RNA viruses that caused

引發伊波拉、寨卡、沙士 同埋新冠肺炎嘅 RNA 病毒都係噉

the Ebola, Zika, and SARS epidemics, and the COVID-19 pandemic.

Once in humans, the virus still mutates—

噉進入人體之後，病毒依然會變異

usually not enough to create a new virus,

雖然唔會通常演變到成為一種新嘅病毒

but enough to create variations, or strains, of the original one.

但都做到啲基因變異出嚟

Coronaviruses have a few key differences from most RNA viruses.

冠狀病毒同大部分 RNA 病毒 有幾個關鍵嘅區別

They’re some of the largest, meaning they have the most genes.

佢哋比較大隻 即係有最多基因

That creates more opportunity for harmful mutations.

噉就更易令有害變異發生

To counteract this risk, coronaviruses have a unique feature:

為咗降低呢種風險 冠狀病毒有一種獨特嘅特點

an enzyme that checks for replication errors and corrects mistakes.

佢含有一種酵素，專門 負責檢查、糾正複製錯誤

This makes coronaviruses much more stable,

咁就令到冠狀病毒更加穩定

with a slower mutation rate, than other RNA viruses.

令到佢比其他 RNA 病毒變異得更慢

While this may sound formidable,

雖然聽起嚟好恐怖

the slow mutation rate is actually a promising sign

但係講到要瓦解冠狀病毒

when it comes to disarming them.

變異得慢係好事嚟

After an infection, our immune systems can recognize germs

因為當我哋感染病菌之後 我哋嘅免疫系統可以識別病菌

and destroy them more quickly if they infect us again

而當我哋再次感染病菌時 就可以更快消滅病菌

so they don’t make us sick.

噉佢哋就唔會再搞到我哋病

But mutations can make a virus less recognizable to our immune systems—

但係病毒變異可以令我哋嘅免疫系統 冇咁容易識別到病毒

and therefore more difficult to fight off.

噉擊退病毒就會難啲

They can also make antiviral drugs and vaccines less effective,

而病毒變異會令抗病毒藥物 同疫苗，變得冇咁有效

because they’re tailored very specifically to a virus.

因為藥物同疫苗 係專門針對某種病毒嘅

That’s why we need a new flu vaccine every year—

噉就係點解我哋每年 都要重新打一次流感疫苗

the influenza virus mutates so quickly that new strains pop up constantly.

因為流感病毒變異得好快 新嘅病毒不斷出現

The slower mutation rate of coronaviruses means

冠狀病毒較慢嘅變異速率

our immune systems, drugs, and vaccines

意味著我哋嘅免疫系統 同埋藥物、疫苗

might be able to recognize them for longer after infection,

喺感染之後嘅一段長時間 都仲可以識別到呢啲病毒

and therefore protect us better.

噉就可以更好咁保障我哋

Still, we don’t know how long our bodies remain immune to different coronaviruses.

目前，我哋依然都未知我哋嘅身體 可以對唔同嘅冠狀病毒免疫幾耐

There’s never been an approved treatment or vaccine for a coronavirus.

面對任何冠狀病毒，永遠都 唔會有一種肯定嘅療法或疫苗

We haven’t focused on treating the ones that cause colds,

雖然科學家開始研發 針對 SARS 同 MERS 嘅治療

and though scientists began developing treatments for SARS and MERS,

但我哋都仲未重點研究感冒治療

the epidemics ended before those treatments completed clinical trials.

喺療法嘅臨床實驗完成之前 疫情就已經結束啦

As we continue to encroach on other animals’ habitats,

有科學家話，鑒於我哋一直喺度 入侵其他動物嘅棲息地

some scientists say a new coronavirus jumping to humans is inevitable—

新嘅冠狀病毒 係無可避免會傳播到人身上

but if we investigate these unknowns, it doesn’t have to be devastating.

但如果我哋要探索未知 都唔一定次次要咁大劑嘅