Since the outbreak of novel coronavirus pneumonia, the origin, propagation and evolution of the new crown virus have attracted much attention. A number of experts at home and abroad said that according to the existing evidence, it is impossible to confirm where the new coronavirus originated.
There is a lack of “jigsaw” in communication
How did the spread of the new coronavirus begin in humans? From the initial reported cases, the South China seafood market in Wuhan was once considered as the source of the epidemic.
In a report on the website of science, Christian Anderson, a biologist at Scripps Institute, speculated that there might be three scenarios for the new coronavirus to enter the seafood market in South China: it could be brought to the market by an infected person, an animal or a group of animals.
A number of experts and studies support these views. According to wilt Ian Lipkin, a professor at the Melman School of public health at Columbia University, who is known as the “virus Hunter”, the new crown virus may not be so directly linked to the seafood market in South China. Perhaps the market is experiencing “secondary transmission”, and the virus began to spread earlier.
Researchers from Xishuangbanna Tropical Botanical Garden and other institutions of the Chinese Academy of Sciences recently published a paper in the form of preprint. They analyzed the genome data of 93 new coronavirus samples from 12 countries on four continents, and found that 58 haplotypes were included. The haplotypes of patients associated with the seafood market in South China were H1 or its derivatives, while those of H3, H13 and h38 were more “ancient” The new coronavirus from South China seafood market was introduced from other places.
To restore the transmission chain of the new coronavirus, scientists still lack some “puzzles”, the most important of which is the first infected person often called “patient zero”. Patient zero is the intersection of many questions, which is very important to find the intermediate host and answer the questions about how the virus spreads from animals to humans.
Virus tracing not completed
How does the new coronavirus survive and evolve in nature before it enters the human body? Researchers from Wuhan Virus Research Institute of Chinese Academy of Sciences and other institutions published a paper in the British journal Nature in February, saying that they found that the gene sequence consistency of the new coronavirus and a coronavirus (tg13) in bats was as high as 96%. Tg13 is the closest strain known to the new coronavirus gene, indicating that bats are likely to be the natural hosts of the new coronavirus.
Other studies have also found that the gene sequence of the new coronavirus is similar to that of the coronavirus carried by pangolin, especially in the receptor binding domain that allows the virus to enter the cell. This suggests that tg13 may have recombined with the coronavirus carried by pangolin during the evolution of new coronavirus.
Jonathan Bauer, a professor of molecular virology at the University of Nottingham, UK, said that the link between the new human coronavirus and pangolin remains a “little question mark” and there is still no final answer to the source of the virus. But if you put all the pieces together, they point to an event where the virus is spreading from animals.
Stanley Perlman, a professor of Microbiology and immunology at the University of Iowa in the United States, believes that the animals that host the new coronavirus may come from outside China, such as the smuggled pangolin.
China’s WHO novel coronavirus pneumonia animal (COVID-19) joint investigation report released in late February also pointed out that the “limitations of existing knowledge” included “animal origin and natural host of virus”, “initial stages of animal to human infection process”, “cases with unknown early exposure”, etc.