A team of biologists at the Kusuma School of Biological Sciences in IIT Delhi wrote a 22-page research paper that was released as a pre-print on bioRxiv on January 31, last year.

It suggested an "uncanny similarity" between aspects of SARS-CoV-2 and HIV, MIT Technology Review reported.

Studying the protein structure of the virus, the team found four unique inserts in the novel coronavirus glycoprotein, not seen in any other coronaviruses. The inserts are critical for the virus to identify and latch onto their host cells in humans and then multiply, media reports say.

However, in response to a deluge of criticism, the paper was withdrawn soon after it was posted. It was the first scientific study signalling the possibility of the virus being engineered.

Various scientists and experts have piled up circumstantial evidence pointing to the theory that the coronavirus may have leaked from the Wuhan Institute of Virology (WIV). The list also includes a Pune-based scientist couple, Rahul Bahulikar and Monali Rahalkar.

Rahalkar is a scientist at Bioenergy Group, Agharkar Research Institute, Pune. Bahulikar is scientist at BAIF Development and Research Foundation, Pune.

While the lab-leak theory has long been dismissed as a conspiracy, it has now become too substantial to ignore.

According to media reports, Bahulikar and Rahalkar started an online expedition at the end of March 2020 to unravel the origins of Covid-19.

They read several scientific papers on coronaviruses and Covid-19 and found that a relative of SARS-CoV-2, RATG13, a coronavirus was collected from a mineshaft in Mojiang of Yunnan province in South China by the WIV.

They also found that the mineshaft was infested with bats and six miners hired to clean the fecal matter were infected with pneumonia-like illness.

They published their findings in the science journal Nature, post which they were contacted by a Twitter user called SEEKER.

SEEKER has been part of a group of amateur sleuths called 'DRASTIC', who with few resources are working to reveal the dark secrets of WIV. DRASTIC stands for "decentralised radical autonomous search team investigating Covid-19" and it has set itself the mission of exploring the origins of SARS-CoV-2.

"Thanks to DRASTIC, we now know that the WIV had an extensive collection of coronaviruses gathered over many years of foraging in the bat caves and that many of them -- including the closest-known relative to the pandemic virus, SARS-CoV-2 -- came from a mineshaft where three men died from a suspected SARS-like disease in 2012," Newsweek reported.

The scientist-duo stated that the claim that Covid-19 originated as a natural infection leaping from animals to humans does not have any proof. According to them, the structure of the SARS-CoV2, the virus behind Covid-19, reveals that it was ready to infect humans, indicating that it might have come from a lab, media reports have said.

They have urged the World Health Organization to probe deeper into lab leak theory.

Meanwhile, US President Joe Biden has also recently ordered the intelligent community to re-double efforts to examine how the virus originated, including the lab accident theory.

The European Union, the UK, Australia, and Japan also have joined the US in seeking a deeper probe into the origins of the pandemic.

China's Foreign Ministry has last week dismissed the Wuhan lab leak theory as "extremely impossible" and have accused the US of "political manipulation", media reports noted.