New research on the origin of Covid-19 published from Chinese data

The above research on the origin of Covid-19 is based on a new analysis of data published by the Chinese Center for Disease Control and Prevention (China CDC), according to the UK 's News Medical website on September 20.

The data involved more than 800 samples collected from January 1, 2020, in and around the Huanan seafood market in Wuhan, China, and from virus genomes reported from Covid-19 patients in the early stages of the pandemic. The new study was published in the journal Cell on September 19.

Enlarged image of cells infected with the Covid-19 virus SARS-CoV-2 (yellow)

"This is one of the most important datasets on the origins of the Covid-19 pandemic that still exists. We are extremely grateful that the data survives and is being shared," said co-author Florence Débarre of the French National Center for Scientific Research (CNRS).

In addition, co-author Michael Worobey of the University of Arizona (USA) said the researchers analyzed the extremely important data collected by the Chinese CDC in new ways. "This is an authoritative analysis of that data and shows that it is consistent with the rest of the huge body of evidence we have about how the pandemic started," Mr. Worobey emphasized.

How the Chinese CDC took samples

On January 1, 2020, after the animals were removed and just hours after the Huanan market closed, investigators from the China CDC visited the market to collect samples. They swabbed the floors, walls, and other surfaces of the stalls. A few days later, they returned to focus on surfaces in the wildlife stalls, such as cages and carts used to move the animals, and collected samples from the sewers.

They sequenced the samples using metatranscriptomics, a technique that aims to obtain all the RNA sequences (and can also get DNA) from all the organisms in the sample, including viruses, bacteria, plants and animals.

The Chinese CDC team published their sequencing data and results in 2023 in the journal Nature . However, that paper did not address the exact identity of the animals found in the data that could represent intermediate hosts. The Chinese CDC has shared its sequencing data on open repositories.

According to the latest analysis of the data published in the journal Cell , the virus that causes Covid-19, SARS-CoV-2, was present in several stalls at the Huanan market, including raccoon dogs and civet cats. In some cases, genetic material from SARS-CoV-2 and these animals were even found in the same samples. The exact species of animals were identified by examining their mitochondrial genomes in the samples.

Raccoon dogs are thought to be susceptible to SARS-CoV-2 and have carried SARS-CoV.

Photo: Screenshot of The Guardian

“Many of these animals were culled before the Chinese CDC team arrived, so we cannot have direct evidence that they were infected. We are studying traces of DNA and RNA from these animals in samples, and at some stalls, SARS-CoV-2 was found,” said co-author Débarre.

“These are the same animals that we know facilitated the initial SARS coronavirus to jump to humans in 2002. This is the most dangerous thing that humans have done – capturing wild animals loaded with viruses and then playing with fire by exposing them to humans living in the heart of major cities, where the high population density makes it easy for these viruses to take hold,” Mr Worobey stressed.

The reason to find the origin of Covid-19

The international team also performed evolutionary analysis of the earliest reported virus genome in the Covid-19 pandemic, and inferred the most likely ancestral genotype of the virus that infected humans and led to the Covid-19 pandemic. The results showed that very few people were infected before the outbreak at the Huanan seafood market. This result is consistent with the spread of Covid-19 from animals to humans at that market, according to the journal Cell.

The new study provides a short list of animals found in the Huanan seafood market that were found in close proximity to or in association with virus samples that may represent the most likely intermediate hosts for SARS-CoV-2. Among them, raccoon dogs, a species susceptible to SARS-CoV-2 and a previous carrier of SARS-CoV, were found to have the most genetic material in samples taken from wildlife stalls at the Huanan market. Genetic material from civets, which have also been linked to the SARS-CoV outbreak in 2023, was also found in a stall with SARS-CoV-2 RNA. Other species such as giant bamboo rats and Malayan porcupines were also found in samples positive for SARS-CoV-2.

While the data cannot prove whether one or more of the above animals may have been infected with SARS-CoV-2, the team's analysis provides a clear list of species that are likely to carry SARS-CoV-2 and the genetic information can be used to help trace their origins.

The researchers stressed the importance of understanding the origins of the Covid-19 pandemic. "There has been a lot of misinformation about the origins of SARS-CoV-2. The reason it's important to find the origins of SARS-CoV-2 is because it affects national security and public health, not just in the United States but around the world . And the truth is that despite increased focus on laboratory safety since the pandemic began more than four years ago, not much has been done to reduce the risk of a zoonotic disease like this happening again," Worobey warned.

Source: https://thanhnien.vn/cong-bo-nghien-cuu-moi-ve-nguon-goc-covid-19-tu-du-lieu-cua-trung-quoc-185240921093431147.htm