The above study on the origin of Covid-19 is based on a new analysis of data released by the Chinese Center for Disease Control and Prevention (China CDC), according to the News Medical (UK) website on September 20.
The data came from more than 800 samples collected from January 1, 2020, in and around the Huanan Seafood Market in Wuhan, Hubei Province, China, and from viral 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 exists 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 matches the rest of the huge body of evidence we have about how the pandemic started," Mr. Worobey emphasized.
How China CDC takes 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. They returned several days later 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 captures all the RNA sequences (and can also retrieve 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 may have represented intermediate hosts. The Chinese CDC has shared their sequencing data on open repositories.
According to the latest analysis of the data published in the journal Cell , the SARS-CoV-2 virus that causes Covid-19 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 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 where 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 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,” Worobey stressed.
Why we need to find the origin of Covid-19
The international team also performed evolutionary analysis of the earliest reported viral genomes of 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, a result 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 to co-occur or be in close proximity to 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 a 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 that tested 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 that 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's a national security and public health issue, not just in the United States but around the world. And the truth is that despite the increased focus on laboratory safety since the pandemic began more than four years ago, little has been done to reduce the risk of a zoonotic event 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
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