New Delhi,  "The Science Suggests a Wuhan Lab Leak", as per an op-ed in the Wall Street Journal by two leading US experts.

Steven Quay and Richard Muller say in the WSJ essay that the Covid-19 pathogen has a genetic footprint that has never been observed in a natural coronavirus.

They said that the possibility that the pandemic began with an escape from the Wuhan Institute of Virology is attracting fresh attention. President Joe Biden has asked the national intelligence community to redouble efforts to investigate.

"Much of the public discussion has focused on circumstantial evidence: mysterious illnesses in late 2019; the lab's work intentionally supercharging viruses to increase lethality (known as 'gain of function' research). The Chinese Communist Party has been reluctant to release relevant information. Reports based on US intelligence have suggested the lab collaborated on projects with the Chinese military," the essay in WSJ said.

"But the most compelling reason to favor the lab leak hypothesis is firmly based in science. In particular, consider the genetic fingerprint of CoV-2, the novel coronavirus responsible for the disease Covid-19," the experts said.

They say that the genome sequencing of Covid-19 suggests that the virus was manufactured inside a Chinese laboratory.

SARS-CoV-2's genetic sequencing almost certainly demonstrates that it is an artificially-manipulated virus developed in a laboratory, they say.

Quay. who had briefed the US Congress on the virus' origins early last year and published a 193-page study in January suggesting the virus was "laboratory derived", and Muller, a Physics Professor at University of California Berkeley, wrote the op-ed in the WSJ.

The experts argued that "the most compelling reason" to support the lab leak theory wasn't related to the circumstantial evidence about Chinese experiments in coronavirus gain of function research, alleged illnesses among lab workers at the Wuhan Institute of Virology or US intelligence reports, but because SARS-Cov-2's "genetic footprint has never been observed in a natural coronavirus".

"In gain-of-function research, a microbiologist can increase the lethality of a coronavirus enormously by splicing a special sequence into its genome at a prime location. Doing this leaves no trace of manipulation. But it alters the virus spike protein, rendering it easier for the virus to inject genetic material into the victim cell. Since 1992, there have been at least 11 separate experiments adding a special sequence to the same location. The end result has always been supercharged viruses," they said in the op-ed.

Covid-19 has the genome sequencing 'CGG-CGG' and the experts assert that no naturally occurring coronavirus - such as SARS or MERS - has ever had a CGG-CGG combination.

"The CGG-CGG combination has never been found naturally. That means the common method of viruses picking up new skills, called recombination, cannot operate here," they wrote in the WSJ.

"A virus simply cannot pick up a sequence from another virus if that sequence isn't present in any other virus".

"At the minimum, this fact - that the coronavirus, with all its random possibilities, took the rare and unnatural combination used by human researchers - implies that the leading theory for the origin of the coronavirus must be laboratory escape," they wrote