Washington, Jul 22 (IANS): Researchers have created a virus in the lab that infects cells and interacts with antibodies just like the Covid-19 virus but lacks the ability to cause severe disease.

This safer virus makes it possible for scientists who do not have access to high-level biosafety facilities to join the effort to find drugs or vaccines for Covid-19, according to the study, published in the journal Cell Host and Microbe.

"I've never had this many requests for a scientific material in such a short period of time, even before we published, people heard that we were working on this and started requesting the material," said study co-senior author Sean Whelan from the Washington University in the US.

To create a model of Covid-19 virus that would be safer to handle, the research team started with vesicular stomatitis virus (VSV).

This virus is a workhorse of virology labs because it is fairly innocuous and easy to manipulate genetically.

Primarily a virus of cattle, horses and pigs, VSV occasionally infects people, causing a mild flu-like illness that lasts three to five days.

Viruses have proteins on their surfaces that they use to latch onto and infect cells. The researchers removed VSV's surface-protein gene and replaced it with the one from Covid-19, known as spike.

The switch created a new virus that targets cells like SARS-CoV-2 but lacks the other genes needed to cause severe disease.

They dubbed the hybrid virus VSV-SARS-CoV-2.

Using serum from Covid-19 survivors and purified antibodies, the researchers showed that the hybrid virus was recognised by antibodies very much like a real SARS-CoV-2 virus that came from a Covid-19 patient.

"Humans certainly develop antibodies against other SARS-CoV-2 proteins, but it's the antibodies against spike that seem to be most important for protection," Whelan said.

"So as long as a virus has the spike protein, it looks to the human immune system like SARS-CoV-2, for all intents and purposes," Whelan added.

The hybrid virus could help scientists evaluate a range of antibody-based preventives and treatments for Covid-19.

"Since the hybrid virus looks like SARS-CoV-2 to the immune system but does not cause severe disease, it is a potential vaccine candidate, the study authors noted.