Meet the Family

Three novel coronaviruses have emerged since researchers first began to warn of the dangers in the 1990s

"Coronavirus" by danielfoster437 is licensed under CC BY-NC-SA 2.0.

Not many of us had taken much of an intelligent interest in coronaviruses until early 2020, when a new mutation of an ancient disease captured the world’s attention. However, a small number of virologists had been sounding the alarm for years, according to Dan Werb’s new and fascinating book on the coronavirus family.

Virologists had known of two other coronaviruses that infected humans for decades, as well as a handful of benign strains. OC43 was first discovered in 1967, while NL63 was first discovered in 2004. Both are found across the globe and are completely endemic. Taken together, they are responsible for up to 30% of all respiratory infections in humans, usually in the form of the common cold. However, their relative harmlessness is likely to be a new adaption.

Scientists have estimated that NL63 began to infect humans between 966 CE and 1142 CE. Although we can’t be absolutely certain, there is strong evidence that it was responsible for a wave of pandemics during the Northern Song dynasty in China, which lasted between 960 CE and 1127 CE.

During the Northern Song dynasty, China was home to up to 100m people - more than the Roman Empire at its peak. The country was ruled from an enormous capital in Kaifeng. The printing press was refined and the regime experimented with meritocracy. However, towards the end of the dynasty, there were 28 major epidemics of incurable respiratory diseases, which researchers now think were caused by NL63. This weakened the regime, which was later overthrown by the Mongols.

Meanwhile, scientists in 2005 realized that OC34 first collided with man around 1889. The timing perfectly coincides with the Russian flu, which exploded in 1889 and 1890 and killed nearly 1m people. Its symptoms included the loss of smell and taste. Researchers think that OC34 was probably related to cattle fever, which spread from around 1850. Large-scale culling operations in the 1870s provided conditions for the virus to jump from cows to humans.

It is time to meet virologist Ralph Baric, who proved in the 1990s just how easy it was for coronaviruses to jump species. His work showed that the ancestor of coronaviruses evolved the ability to infect a common ancestor to humans and other species some 300m years ago. This is an enormous number. To put it in context the asteroid that ended the age of the dinosaurs was just 65m years ago. The first coronaviruses were already very ancient around 250m years ago at the dawn of the Mesozoic Era, which was characterized by the dominance of dinosaurs and other reptiles.

Baric sounded the alarm in the 1990s that we should expect new outbreaks of coronavirus - a very prescient prediction. Studying coronaviruses had been something of a scientific backwater when he decided against studying HIV in the 1980s. He decided to follow his curiosity instead. Coronaviruses are the largest RNA viruses. They appear too large. Why?

By 2007, Baric and his collaborators had worked out that a nonstructural protein called nsp14-ExonN acted as proof-reader for coronaviruses, effectively removing random errors. This slowed the evolution of the viruses but stretched the size of their genomes. Mystery solved!

Since Baric first sounded the alarm about coronaviruses in the 1990s, humanity has been struck three times. The first time as was in late 2002 to 2003, when severe acute respiratory disease (SARS) emerged. The first cases involved butchers, market vendors and chefs in Guangdong Province in China, but it spread throughout Asia and further afield.

Scientists mapped the genome of SARS, showing it to be a member of the coronavirus family. It was traced to horseshoe bats, who are a natural reservoir of the virus and share a common ancestor with humans around 100m years ago.

SARS was successfully contained through public health measures by 2005, but a new novel coronavirus broke out soon afterwards. This was the Middle East respiratory syndrome (MERS), which emerged in Saudi Arabia in 2012. Brave Egyptian scientist and whistleblower Ali Zaki had to flee the autocratic kingdom after warning the world of the threat.

Virologist Malik Peiris found that coronavirus had been endemic for many years in dromedary camels, which share a common ancestor with humans some 85m years ago. Although there is no exact consensus on how MERS was spread, slaughterhouses appeared to play a crucial role. The disease was eventually controlled with public health measures, including warnings against consuming raw camel milk or meat.

The third outbreak of a novel coronavirus was - as we all know - SARS-CoV-2 in Wuhan province. It later became known as COVID-19. The work of unsung virologists studying coronaviruses for many decades beforehand paved the way for the development of revolutionary new vaccines in record time, which in turn have given us better results than the Chinese nearly 900 years ago.

Having said that, the next challenge for virologists is to find a vaccine that can prevent serious illness following infection from any member of the coronavirus family. The comments are open. See you next week!

Further Reading

The Invisible Siege by Dan Werb

A Story of Us

The Ancestor's Tale

Sharpen Your Axe is a project to develop a community who want to think critically about the media, conspiracy theories and current affairs without getting conned by gurus selling fringe views. Please subscribe to get this content in your inbox every week. Shares on social media are appreciated! If this is the first post you have seen, I recommend starting with the first-anniversary post, which includes links to a free book.

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