The new coronavirus continues to mutate and mutated strains continue to appear. Among them, two strains found in 2020 have become or are becoming the leading strains of the global epidemic: Delta and lambda. Tracking and understanding the characteristics of mutant strains and the scientific truth behind them is very important for the research and development of vaccines and drugs.
Delta first appeared in India in 2020. A year later, it spread all over the world and became the main mutant in many parts of the world. The speed and range of transmission are amazing; Ramda strain first appeared in Peru, South America. A year later, it began to spread rapidly around the world and showed some characteristics that need to be vigilant.
The production of mutant strains is the result of mutations in the process of virus self replication. The virus will continue to replicate itself throughout its life. During this period, it will often mutate and produce mutant strains. The more replication, the more infected people, the greater the probability of mutation and the number of mutations. Mutant strains that need to be vigilant will lead to easier reproduction, faster transmission, or stronger resistance to vaccines and drugs.
Here are some basic problems about ramda, Delta and virus mutation; How did the mutant strain come into being? Will the virus mutation stop? Which variants must be vigilant? Will the vaccine fail to the mutant strain?
Uncover the secrets of ramda strain
The ramda variant was first discovered in Peru in August 2020 and was listed in the list of “virus of interest” (VOI) variants by the World Health Organization (who) in June 2021. So far, it has not been upgraded to the more serious category of “virus of concern” (VOC). With the increase of ramda infection cases, as of mid August, ramda traces had been found in nearly 30 countries. Scientists warned that the ramda mutant strain, scientific name c.37, may be more infectious and spread faster than Delta.
The most vaccinated in Peru is koshing vaccine. The team of Grossman School of medicine of New York University carried out a study on the effectiveness of koshing vaccine against ramda strain in Peru. The conclusion is that this strain is “partially resistant” to koshing vaccine, but “it is unlikely to significantly reduce the immune efficacy”; The study has not been peer reviewed. According to the definition of who, “noteworthy” strains have the following characteristics: they appear in multiple countries / regions, and the mutation has a confirmed or suspected significant impact on the infectivity and severity of the virus.
Who is tracking the ramda strain. If this variant is found to increase the infectivity and severity of NCV, it may be upgraded to a “concern” variant – increased virus infectivity, harmful changes in epidemiological significance, increased toxicity, changes in disease symptoms or manifestations, and evidence of testing, treatment and preventive measures A team at New York University’s Grossman School of Medicine found that a mutation called l452q tripled the infectivity of the ramda strain.
Known characteristics and symptoms of infection
England public health agency (PHE) And the scientific research team are conducting national follow-up investigation on the discovery of ramda strain to understand, understand and evaluate the impact of this mutation on virus behavior. Delta is still the leading strain of the epidemic in the UK, but ramda strain infection cases have emerged. There is not enough data to answer whether the existing new crown vaccine is effective for ramda strain, but there are researches that have not been peer-reviewed The report shows that mRNA vaccines, including Pfizer and Modena, are effective against ramda strain.
Another study, also unpublished, showed that ramda strain “has the ability to escape neutralizing antibodies triggered by koshing vaccine” At present, there is little evidence to show how the ramda strain is different from other variant strains. Scientists emphasize that the follow-up investigation and research is still in the early stage, and more solid research data are needed to fully understand the role of this variant strain. NHS The main symptoms of the published ramda variant virus infection include high fever, persistent cough (lasting for about an hour or at least three attacks within 24 hours), changes in smell and / or taste.
The new coronavirus is spreading all over the world, and virus variation continues to occur
According to a paper published in the journal Nature in July 2021, scientists are approaching the truth: the transmission rate of delta virus strain has so far exceeded twice that of the original strain, probably because people infected with this strain produce more new coronavirus, making it easier to spread.
According to the available data, delta mutant strain poses a greater threat to public health: the transmission rate is about 60% higher than alpha, and the transmission rate of alpha is 50% higher than that of the original strain of neocoronavirus. From the earliest discovery in India in 2020 to the summer of 2021, delta strain has not only spread all over the world, but also become the leading strain in most parts of the world.
The team of China Guangdong Center for Disease Control found that the virus carried by patients infected with delta strain is about 1000 times that of the original strain, and the incubation period is short. The combination of the two may be the main reason for the unusually rapid spread of delta strain. Some infectious and genetic geneticists also believe that the virus load of delta strain is different from that of the original strain The difference between the incubation period and the original strain and other variant strains may change, but the pathological mechanism can explain the transmission characteristics of this variant strain.
Previous studies have also shown that the biggest difference between Delta and other new coronavirus strains is that delta no longer has loss of smell and taste, so it is more like a severe cold. In late June 2021, India included delta + variant of delta virus strain in the list of concerns. There is a new mutation (k7n) in the spike protein of this variant The Indian Ministry of Health says delta + is easier to spread, binds more easily to lung cells and may become resistant to a drug therapy called monoclonal antibody therapy.
New crown epidemic: six key problems of delta virus mutation
Which mutant strains should be vigilant?
Like all virus variants, most changes are insignificant, some are even beneficial, but some are dangerous, which will enhance the infectivity or lethality of the virus, and unfortunately, such variants often dominate.
At present, the four known variant strains are the most interesting:
Delta variant strain (b.1.617.2) was first found in India,
Alpha variant strain (b.1.1.7), first discovered in Kent, UK, has spread to more than 50 countries / regions and may still be mutating,
Beta variant strain (b.1.351), first found in South Africa, has spread to at least 20 other countries / regions
Gamma variant strain (P.1), first found in Brazil, has spread to more than 10 other countries / regions
Alpha, gamma and beta mutant strains all have a mutation called n501y, which seems to strengthen the virus’s infectivity to cells and make the virus easier to spread.
Beta and gamma mutant strains also have a key mutation, called e484k, which may enable the virus to avoid the resistance of the immune system. Delta mutant strains may be easier to spread. They are listed as “worthy of concern” by the World Health Organization (who) The list of variants is because they pose a greater threat to public health, such as the virus is more infectious, resulting in more serious diseases or stronger resistance to vaccines. Other important variants are listed as “noteworthy” because they are found to spread in multiple countries or cause disease clusters.
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How does the virus mutate?
Every time the new coronavirus infects the human body, it is the result of the continuous replication of sars-cov-2 virus. Each replication requires the replication of its own genome. Small errors may occur in the process of replication, so the new genome may be slightly different from the previous ones. In short, these small errors are mutations, also known as mutations, resulting in the mutated strains of the virus; the mutations will continue As it continues to occur, there are more and more mutant strains.
Most mutations have no effect on the behavior of the virus, but occasionally, mutations will also cause changes in the behavior of the virus. At present, there are two main mutations found, both of which appear on the spike protein of neocoronavirus; spike protein is an important part for the virus to unlock and enter human cells.
The n501 mutant strain changes the most important “binding receptor” of the new coronavirus spike, which is the place where the virus spike first contacts human cells. Any mutation that makes the virus easier to enter the cell will make it more advantageous. Nick Loman, an expert of the British new coronavirus genome (cog-uk) From this point of view, this mutant strain is of great concern. Another mutation is the deletion of H69 / V70. The research of Professor Ravi Gupta of Cambridge University shows that this mutation triples the infectivity in laboratory experiments and weakens the efficiency of antibodies in survivors’ blood to attack the virus.
What are the different behaviors of the mutant strains?
In the process of adaptation, the virus has many skills to make it easier to spread. For example:
More effective invasion of human cells; early warning mechanism for deeper penetration into human cells; longer survival in the air; increase the virus content released by patients’ breathing and cough; virus variation will involve advance and retreat in the evolutionary sense – progress on the one hand may be at the cost of retreat on the other. For example, viruses may sacrifice parts in the process of competing with vaccines Sub communication ability.
At present, it is difficult to predict the degree of virus variation, because it is not only the number of mutant strains, but also various factors such as infectivity, harmfulness, effective time of immunity and so on.
Is the vaccine effective against the mutant strain?
Studies have shown that the existing vaccines are still effective against new mutant strains. This is because Pfizer, Modena and Oxford have trained the human immune system against virus spike, and the mutation of new coronavirus spike protein makes people worry about whether it will affect the effectiveness of the vaccine.
However, the vaccine also trains the immune system to attack several different parts of the virus, so even if some spikes mutate, the vaccine should still be effective and may be less effective. In a study by the UK Department of public health, a dose of Pfizer or AstraZeneca vaccine provided only 33% protection for the delta variant and 50% for the alpha variant. However, these water Ping rose to 88% of Pfizer and 60% of AstraZeneca after the second administration.
Virus mutation indicates that the virus is constantly adapting to the environment in order to survive. What needs to be vigilant is that the virus has more mutations, so that it can avoid the obstruction of the immune system and continue to infect the human body. New coronal pneumonia may be like influenza in the future, and the vaccine needs to be updated regularly. Influenza virus changes very quickly, so we need a new vaccine every year; sars-cov-2 virus does not change like influenza virus The mutation is so rapid, but the continuous occurrence of new mutations may also require regular supplementary vaccination.
How to deal with the continuous virus mutation?
In addition to shortening the interval between two injections and accelerating the popularization of vaccination, virus DNA sequencing should also be improved to identify mutations and variants in a more timely manner, so as to prevent the occurrence of the epidemic, or effectively curb the spread of the epidemic. The main indicator for comparing the virus transmission ability is R0, which means that when no one has immunity and no epidemic prevention measures are taken, The number of people infected by a virus carrier.
At the beginning of the epidemic in Wuhan in 2019, the R0 value is about 2.5, and the R0 value of delta variant strain may be as high as 8.0. At present, the academic community has different opinions on how high the R0 value of new coronavirus can rise, but it is generally believed that the transmission capacity of the virus will increase by leaps and bounds in the next few years. At present, the highest R0 value of all infectious diseases belongs to measles, ranging from 14 to 30. Although vaccine is the main means to control the epidemic However, the vaccine itself may also lead to new coronavirus mutation and virus mutation that cannot afford immune response.
With more and more people recovering from infection and vaccinated, the virus is also facing greater survival pressure, and the possibility of mutated virus that will not cause human immune response is higher. However, there is an ultimate limit to virus mutation. ARIS Katzourakis, an expert on virus evolution at Oxford University Of course, the most effective way to curb the endless emergence of new coronavirus mutant strains is to reduce global new coronavirus infection cases, because each new infection is an opportunity for the virus to mutate and change its behavior.