Will Iceland's first "dually infected" virus "evolve" stronger

■ Observer

The discovery of two different subtypes of New Coronavirus in a person in Iceland indicates that the mutation speed of New Coronavirus has recently accelerated, posing new challenges to the development of drugs and vaccines.

According to the Beijing News, on March 24, Iceland said that a patient with New Crown Pneumonia in the country was detected with two new crown viruses in the body, one of which is a variant of the original virus, which may be the first time that a “double infection” has been detected in the world . The news aroused public opinion. At the same time, a local gene company in Iceland, DeCODE, performed genetic sequencing analysis of confirmed cases in the country and found 40 variants of the new coronavirus.

In general, mutations in viruses are normal. The emergence of "dual infection" in Iceland this time, combined with the previous situation of changes in new crown virus in some countries, may indicate that the new crown virus is slowly "evolving." However, whether its toxicity and infectivity are enhanced requires further research.

However, the change in the virus itself also suggests that people may have more difficulties in dealing with the new crown virus and accept more severe challenges.

On March 26th, the director of the National Institutes of Health, Francis Collins, pointed out in a blog post entitled "Gene Research Shows New Coronary Pneumonia Virus Originating in Nature", based on the The discovery of Christian Anderson and others can determine that the new crown virus (SARS-CoV-2) is a naturally evolved virus, and its toxicity to humans also evolved naturally.

In fact, the evolution of new crown virus infections into humans is itself lengthy. First, it evolved in its natural host (may be a bat or pangolin), and then passed through the intermediate host. If the civet, etc., mutated its spike protein, and evolved a molecule that can be similar to the ACE2 receptor structure in human The ability to bind and infect human cells.

However, there are now two different subtypes of New Coronavirus in a person in Iceland, which indicates that the mutation speed of New Coronavirus has accelerated recently, but whether its toxicity and infectivity have also increased simultaneously remains to be seen.

In fact, the new crown virus in China has also changed, but it is not significant. The Institute of Zoology, Chinese Academy of Sciences found the virus on January 11, and after determining the entire genome of the virus, no major mutations have been found to this day. This situation is not the same as that found in other countries.

The biological characteristics of a virus determine its rate of mutation. New crown viruses use RNA as genetic material. Unlike organisms that use DNA, these viruses cannot repair errors that occur when they replicate the genetic code. This means that RNA viruses tend to evolve faster than other viruses, but they must not mutate too much, because mutations that are too large can make it difficult for viruses to replicate and survive.

The infectivity of the virus and the harm to the host are still controlled by multiple genes, and the common change of multiple genes may cause increased toxicity and increased harm to humans. But changes in multiple genes take more time, which makes such changes unlikely in months or years.

The virus mutation in Iceland may be just a genetic change, so it happened in just a few months. As for whether the mutant virus is more toxic and more harmful to humans, you need to observe other genes. No change.

The presence of two viruses in the same person in Iceland also indicates that humans may have a more difficult task in the future against the new crown virus.

On the one hand, the development of vaccines and drugs has created obstacles as viruses change. One of the biggest possibilities is that when the vaccine or drug was developed, the virus had already mutated, so the effectiveness of drugs and vaccines must be reduced.

On the other hand, if the virus mutates frequently, like the HIV virus, even a small number of mutations may cause some mutated viruses to become resistant to the drug after the drug is developed. Due to drug resistance, such mutated viruses can survive and retransmit to others, thereby causing unfavorable or prolonged treatment of new coronary pneumonia.

In this case, humans have to adopt new strategies to combat new crown pneumonia, as in the case of AIDS. A combination of multiple drugs (cocktail therapy) is needed to prevent new crown viruses from becoming resistant to the drug due to mutations.

Taken together, the emergence of two new coronavirus subtypes in one person in Iceland may not be a significant threat to humans in the short term, but in the long run, human beings must be prepared and there must be more plans for vaccines and drugs To cope with the possible changes in the virus.

□ Zhang Tiankan (column author)