Boston University scientists were today condemned for 'playing with fire' after it emerged they had created a lethal new Covid strain in a laboratory. DailyMail.com revealed the team had made a hybrid virus — combining Omicron and the original Wuhan strain — that killed 80 per cent of mice in a study.

The revelation exposes how dangerous virus manipulation research continues to go on even in the US, despite fears similar practices may have started the pandemic.

Professor Shmuel Shapira, a leading scientist in the Israeli Government, said: 'This should be totally forbidden, it's playing with fire.'

Gain of function research - when viruses are purposefully manipulated to be more infectious or deadly - is thought to be at the center of Covid's origin.

A Chinese laboratory located just miles from the first cluster of cases carried out similar research on bat coronaviruses.

But the practice has been largely restricted in the US since 2017.

Dr Richard Ebright, a chemist at Rutgers University in New Brunswick, New Jersey, told DailyMail.com that: 'The research is a clear example of gain of function research.

He added: 'If we are to avoid a next lab-generated pandemic, it is imperative that oversight of enhanced potential pandemic pathogen research be strengthened.'

80 percent of mice died from the new man-made Covid strain, while none died from the milder Omicron variant alone, researchers at Boston University's National Emerging Infectious Diseases Laboratories found.

Dr Richard Ebright, a Rutgers University chemist, said that this research could spark the next lab-created pandemic. Professor Shmuel Shapira (right), a leading scientist in the Israeli Government, said that this type of research should be banned as it is playing with fire.

In the new research, which has not been peer-reviewed, a team of researchers from Boston and Florida extracted Omicron's spike protein — the unique structure that binds to and invades human cells.

It has always been present in the virus but has become more evolved over time. Omicron has dozens of mutations on its spike protein that made it so infectious.

Researchers attached Omicron's spike to the original wildtype strain that first emerged in Wuhan at the start of the pandemic.

The researchers looked at how mice fared against the new hybrid strain compared to the original Omicron variant.

When a similar group of rodents were exposed to the standard Omicron strain, however, they all survived and only experienced 'mild' symptoms.

Writing in the paper, they said: ‘In...mice, while Omicron causes mild, non-fatal infection, the Omicron S-carrying virus inflicts severe disease with a mortality rate of 80 percent.’

The researchers said it signaled that while the spike protein is responsible for infectivity, changes to other parts of its structure determine its deadliness. Have we learned nothing? 40 new biochemical labs that handle dangerous viruses are being built around the world The Coronavirus pandemic has prompted a global surge in laboratories that handle dangerous viruses — despite concerns Covid may have been the result of the risky experiments.

More than 40 facilities certified as biosafety level 3 (BSL-3) or BSL-4 have either been built or have gone into construction since 2020, predominantly across Asia.

Many countries believe they were caught flat-footed by Covid and want to get ahead of the next devastating outbreak by studying pathogens that pose a threat to humans.

Experiments at these labs often involve tinkering with animal viruses to advance treatments and vaccines that could be used in a future outbreak.

But there are widespread concerns that these experiments might actually raise the risk of pandemics — something some experts believe was the case with Covid.

The virus first began spreading from a wet market in Wuhan, about eight miles from the Wuhan Institute of Virology (WIV),