The latest findings of the Chinese scientific research team show that the new coronavirus (Covid-19) has recently generated 149 mutation points and has evolved into two subtypes, namely L subtype and S subtype.
Has the new coronavirus been mutated? How to mutate? This is one of the focuses of current academic research.
The study found that the two subtypes showed significant differences in geographical distribution and population proportions.
The S type is a relatively older version, while the L subtype is more aggressive and more contagious. An in-depth understanding of different subtypes will help differentiated treatment and prevention of new coronary pneumonia.
The above research comes from the paper "On the origin and continuing evolution of SARS-CoV-2"published on March 3 by the National Science Review sponsored by the Chinese Academy of Sciences.
Corresponding authors of the thesis are: Researcher Lu Jian (Bioinformatics Center, School of Life Sciences, Peking University), and Researcher Cui Jie (Shanghai Pasteur Institute of Chinese Academy of Sciences).
In the dissertation, by analyzing the evolution of the whole genome of 103 novel coronaviruses with the largest scale, it was found that 149 mutations have occurred in the virus strains, and most of them have been generated recently.
The study revealed that new coronaviruses have evolved into two subtypes, L and S. Of these, 101 belong to these two subtypes. In terms of proportion, the L subtype reached 70% and the S subtype accounted for 30%.
The author of the paper believes that, based on the evolution of the new coronavirus, there may be a large difference in the transmission ability and severity of disease of the L and S subtypes.
The paper states that the difference between the two subtypes is at the 28144 position of the viral RNA genome. The L subtype is the T base (corresponding to leucine, Leu), and the S subtype is the C base (corresponding to serine, Ser).
By comparing with other coronaviruses, the authors found that the new type S coronavirus is closer to the bat-derived coronavirus on the evolutionary tree, and thus concluded that the type S is relatively older.
The L subtype was more common in the early stages of the outbreak in Wuhan, and the frequency of the L subtype decreased after early January 2020.
The authors believe that human intervention may exert greater selective pressure on the L subtype, and without these interventions, the L subtype may be more aggressive and spread faster.
On the other hand, because the selection pressure is relatively weak, the older and less aggressive S-types may have increased in relative frequency.
These findings mean that there is an urgent need to conduct further comprehensive studies combining genomic data, epidemiological data, and chart records of clinical symptoms of patients with coronary virus disease in 2019.
In addition, it is worth noting that these 103 samples showed that most patients were infected with only one of the L or S subtypes.
However, a virus strain isolated from one of the American patients who has recently traveled to Wuhan showed that they may be infected with both L-type and S-type new coronaviruses.
However, the author states that the possibility of new mutations cannot be ruled out at this time.
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