There’s a 2nd, more dangerous coronavirus strain - mutations

Chinese scientists who compared the genetic sequences of 103 viral samples from patients infected with COVID-19 said their evidence suggests that the virulent version of the coronavirus — which they tagged the “L-type” version — was the dominant strain in the earliest phase of the outbreak that began in Wuhan late last year. That strain, they said, appeared to recede as the epidemic progressed.

But among samples collected later, as COVID-19 spread across China and into other countries, a variant of the virus they dubbed the “S-type” was more common, the scientists reported. They suggested that the genetic makeup of the S version more closely resembles coronaviruses circulating in bats and pangolins, the animals that are thought to have incubated the virus before it jumped to humans. And they surmised that it is a less virulent version.

The findings suggest the S-type version of the coronavirus may have escaped its animal hosts earlier than previously believed — and that it may have been circulating longer without causing enough illness to set off alarm bells.

The Chinese scientists reported their analysis Thursday in the journal National Science Review. The team was led by Peking University’s bioinformatics researcher Jian Lu in Beijing.
The study authors acknowledged that their conclusions are very preliminary and are based on a very small sample of viruses. The variations they found will need to be observed in many more specimens taken from other patients, and their genetic differences will need to be compared with physicians’ reports and epidemiological notes. Only then can their suspicions can be confirmed, they wrote.

Officials at the World Health Organization warned that “it’s important we don’t overinterpret” the scientists’ findings.

Some geneticists who weren’t involved in the study argued that the data could support an alternative interpretation: that the virus has simply spread more widely than they had realized, picking up random mutations along the way. Those mutations may or may not make the virus behave differently.
If the S-type of the virus is the older version that was circulating first, a final mystery remains: Why would the majority of samples taken from the initial patients in Wuhan have fallen into the L-type category? Shouldn’t there be more S-types in the mix?
This is where the Chinese scientists make a hotly debated leap: They surmise that the newer L-type version probably picked up more mutations, and evolved further from the bat coronavirus from which it originated, because it either infects people more readily or it replicates more vigorously once it infects.

A group of researchers from the MRC-University of Glasgow Center for Virus Research in Scotland offered a more detailed rebuttal of the new paper. Among other things, they said the study authors misinterpreted their data and failed to account for limitations in their statistical methods.
“Given these flaws, we believe that Tang et al. should retract their paper, as the claims made in it are clearly unfounded and risk spreading dangerous misinformation at a crucial time in the outbreak,” the Glasgow team wrote.

There’s a 2nd, more dangerous coronavirus strain - mutations There’s a 2nd, more dangerous coronavirus strain - mutations Reviewed by Anson Moore on March 19, 2020 Rating: 5

No comments:

Powered by Blogger.