The technology developed by Thiel’s team was based on the idea of reverse genetics.

In theory, biological engineers can recreate a life form if they know its full genome sequence. In real life though, they can only synthesise some simple organisms with short genome sequences.

The coronavirus is extremely challenging to make from scratch, even in the best-equipped laboratory, because its genome is longer than that of most other viruses.

Thiel and Jores found a key to solving the problem in a yeast called Saccharomyces cerevisiae. Also known as brewer’s yeast, the fungus has been used for thousands of years to make wine, beer and bread.

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In the planning stage, the researchers divided the coronavirus genes into 14 fragments; they then bought most of these fragments from a biology company. They put the fragmented genes into the yeast, which automatically combined them piece by piece, from head to tail, until a complete genome was formed.

The recombined genome could not infect cells as a virus does. But using electricity, the scientists injected the man-made genome into a cell to mimic the viral infection. Once in the cell, the viral genome started replicating and mass-producing the fully formed virus with genetic material wrapped in spiky protein shells.

With the yeast-based technology, scientists could create an active strain in a week after obtaining the sequencing data, according to the researchers.

These man-made strains would “functionally characterise Sars-CoV-2 evolution in real time”, they said.

A common problem for artificial viruses is that their mutations may run wild. A virus mutating too much and too fast was useless, but the new strain, dubbed rSars-CoV-2, remained stable after several generations.

Since it was first reported in Wuhan, China in December, Sars-CoV-2 – the pathogen causing the Covid-19 disease – has spread to every populated continent and caused a global pandemic. By Wednesday, Chinese scientists had detected 5,771 mutations that occurred when the virus tried to adapt to different environments and populations, according to the China National Centre for Bioinformation.

It was not the first time that scientists have created a coronavirus in the lab. Scientists have synthesised severe acute respiratory syndrome (Sars) and Middle East respiratory syndrome (Mers), two strains that have caused regional outbreaks.

A team of researchers led by Pei-Yong Shi of the University of Texas Medical Branch in Galveston reported in the journal Cell Host & Microbe last month how they had created a man-made Sars-CoV-2 strain using a different approach.

Shi’s team joined the gene fragments in a test tube instead, and said a few extra genes to the virus to make it glow under a fluorescent light so infected cells were easier to spot.

Zhang Shuye, principal investigator with the Shanghai Public Health Clinical Centre at Fudan University, said reverse genetics gave researchers a powerful tool to manipulate the genes of a virus of natural origin for research purposes.

But reverse-engineering the coronavirus remained a challenging task. Only a few countries, such as the United States, China and some in Europe, were capable, according to Zhang.

Zhang said the man-made strains would help the fight against the pandemic. Although computers could predict the impact of a changing gene on the virus’ form and functions, the models could sometimes make a mistake.

An artificial virus would allow researchers to fill the gap between real life and theory in their search for cures and effective prevention strategies, Zhang said.

“Much of our understanding of the coronavirus remains a guess, and [researchers] desperately need experimental proof.”

He also warned that such experiments must be conducted in guarded laboratories with biosafety level-3 or higher security protocols.

“Man-made strains are strictly forbidden to be released into the wild. If these experiments are conducted in a protected facility, the risk will be extremely low,” he said.