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They were only discovered two years after they were infected with the new coronavirus
At first thought it was a rash, but it turned out to be a new crown?
!
The samples from the “bottom of the pressure box” of the University of Milan, Italy, “vomited” the unexpected truth: the owners of these samples went to the hospital about two years ago because of a rash (measles, rubella, etc.). Two years later, the researchers performed their samples. After further research, it was discovered that he was actually infected with the new coronavirus.
On August 7, this research led by researchers from the Department of Biomedical Sciences of the University of Milan, Italy was published online on the "Lancet" preprint website (this paper has been submitted to the "Lancet" magazine, and has not yet been peer reviewed and accepted ).
"Our research provides strong evidence that the new coronavirus has spread in northern Italy in the late summer of 2019." The paper wrote that compared with the early strains found in Wuhan, this strain is very different. !
"The significance of this research is very significant and the evidence is reliable. In the future, it may lead to changes in our human perception of the new coronavirus and expand the scope of traceability." On August 10, a reporter from Science and Technology Daily connected with a domestic virus traceability expert and Beijing. Tong Yigang, the dean of the School of Life Science and Technology of the University of Chemical Technology and the Chinese leader of the Animal and Environment Group of the China-WHO Joint Research Expert Group on the Traceability of New Coronavirus, made the above evaluation.
The truth is hidden in the discarded samples: there are already new coronaviruses in the 9 samples in 2019
An anomaly in 2019 caught the attention of researchers-
"We found that the number of samples that were diagnosed as non-measles or non-rubella and discarded was particularly large in 2019." The researchers explained in the paper that this discard rate was twice that of previous years.
This laboratory at the University of Milan is a WHO-approved measles and rubella monitoring agency. Based on past experience, they have realized that there is an unknown cause that makes people appear to be suffering from measles, but when they are actually diagnosed, it is And found it was not.
So, what is the reason for the unknown?
The researchers decided to start looking for answers in abandoned samples.
The samples include oropharyngeal swabs, urine, and serum, all stored in a sample bank at minus 80 degrees Celsius in the Biological Laboratory of the University of Milan.
The study conducted investigations on 435 samples from 156 cases of new coronavirus infection, including nucleic acid testing and antibody testing.
The nucleic acid test results showed that 13 cases were positive, 11 of which were pre-pandemic cases, and 9 of the 11 positive samples were sampled in 2019.
The paper recorded more surprising details: the first sample that tested positive for the new coronavirus RNA was a urine sample collected as early as September 12, 2019. The sample came from an 8-month-old child whose serum was also It was positive for IgG and IgM.
Whether it is a nucleic acid test or an antibody test, it proves that two years ago, someone had been infected with the new coronavirus in Italy.
"Nucleic acid testing is very important. It intuitively gives a positive result. At the same time, with the supporting evidence of antibodies, the evidence is very solid." Tong Yigang analyzed, and it is worth noting that this study is not the discovery of a single case, but a large cohort. The study of the population is of great practical significance for traceability.
Compared with the virus strains discovered in Wuhan, it has brought more cognitive conflicts: the family pedigree is "inferior"!
"In the two weeks before the onset of the rash, all positive patients did not report any travel history." The paper specifically pointed out that it is important that all confirmed cases, including 9 cases in 2019, are not related to travel.
This means that the new coronavirus before detection has begun to spread locally in Europe.
So, is the new coronavirus that spread in Italy the same as the one that is believed to be the "ancestor" and spread in Wuhan?
The research team performed a nucleic acid sequence comparison and detected three main variants.
More importantly, the major mutations at this locus are all three major mutations detected for the first time a few weeks after the outbreak in China, namely C3037T, C14408T and A23403GT, all of which belong to the "beta mutation".
This is no coincidence!
Because the mutation did not occur after the epidemic, but before the new coronavirus strain was discovered in Wuhan.
Use a dialect to explain: I'm inferior!
I used to think that the "beta mutation" was the "descendant" of the strain found in Wuhan, but in fact, the "beta mutation" strains spread earlier in other regions and have already been upgraded to "grandpa generation".
Researchers believe that the results show that several lineages of the new coronavirus have been circulating around the world for at least a few weeks before the first report of the new coronavirus case in Wuhan, China.
An evolutionary analysis based on the gene sequence showed that β mutations already existed in the strains in the last quarter of 2019, which means that there was already a coronavirus lineage very different from the presumed ancestor in northern Italy at that time.
As the new coronavirus strain in September 2019 has been able to effectively spread from person to person, researchers have advanced the predicted date of the emergence of the "originator" of the new coronavirus to between the end of June 2019 and the end of August 2019.
More puzzles to be solved, call on scientists from all over the world to "turn the bottom of the box" together
"Although these samples were not collected to detect the new coronavirus, the retrospective study finally gave the decisive answer to the question." The author of the paper called on other research teams to use the samples stored in the biobank to conduct additional retrospective studies. To further search for early cases of new coronavirus infection, because these are essential to more accurately determine the time and location of the virus.
Virus traceability, samples are king, so the thesis researchers call on scientists from all over the world to "turn the bottom of the box" together!
The process of this research also shows that innovative technology is also king.
The researchers admitted that these samples may not be ideal for the detection of the new coronavirus because they were collected when the rash appeared. At that time, the viral load in the respiratory tract was very low, which made the detection difficult.
However, the research team used innovation to overcome difficulties. They improved the detection method and the primer design, and finally "catch" the "little pigtail" during the hidden epidemic of the new crown virus and pulled it out.
More and more scientists, with their own practice and innovation, have proved that virus traceability is a scientific issue. It is necessary to proceed from a scientific point of view to promote early case search, molecular epidemiology, animal (intermediate) ) Traceability of the host and other aspects.
The paper also pointed out: "We suggest that during the investigation of the origin of the virus, a wider geographical area and a wider time span should be considered." (Reporter Zhang Jiaxing)