New research by one of the leading Chinese scientists found that the mutation capability of the new strain of corona virus has been underestimated compared to reality.
Professor Li Lanjuan and colleagues at Zhejiang University found that in a small group of patients, many mutations had not been reported previously. These mutations include changes so rare that scientists never thought they could happen.
Certain mutations can produce more deadly strains
The scientists also confirmed for the first time with laboratory evidence that certain mutations can produce more deadly strains than others.
“Sars-CoV-2 had mutations that could dramatically alter disease levels,” Professor Li and colleagues wrote in an article published on medRxiv.org on April 19.
Professor Li’s study provides the first evidence that mutations can affect the severity of the virus causing illness or the degree of harm to the host.
Ms. Li took an unusual approach to investigate the virus mutation. The female expert analyzed virus strains isolated from 11 randomly selected Covid-19 patients from Hangzhou city in Zhejiang province, and then checked whether they could infect and kill the cells. how.
The most dangerous mutations in Zhejiang patients have also been found in most patients across Europe, while lighter strains were found in parts of the US, such as Washington State, according to the group’s article. research.
Another study earlier found that the virus strain in New York came from Europe. The death rate in New York is similar to many countries in the old continent, even higher.
However, a weaker mutation does not mean a lower risk for the patient, according to Professor Li’s research. In Zhejiang, two patients in their 30s and 50s infected with the weaker strain of corona virus became seriously ill. Although both survived, older patients had to be treated in intensive care.
May clarify the differences in mortality
This finding may shed light on differences in regional mortality. The prevalence and mortality rates of pandemics vary from country to country, and there are some explanations now.
Genetic scientists have found that the virus strains in different geographical areas are inherently not the same. Some researchers suggest that the different mortality rates may be partly due to mutations but there is no direct evidence.
The problem is even more complicated because survival rates depend on many factors, such as age, health condition, background disease or even blood type.
In hospitals, Covid-19 was treated as an illness and patients were treated the same regardless of strain. Professor Li and colleagues suggest that identifying mutations in an area could help determine how to fight the virus.
“The development of drugs and vaccines, while urgent, needs to take into account the impact of these cumulative mutations to avoid potential dangers,” the scientists said.
According to Chinese media, Professor Li was the first scientist to propose a blockade of Wuhan. The Chinese government followed her recommendation in late January, blocking the city of more than 11 million people.
Ms. Li’s team detected more than 30 mutations. Among them, 19 mutations – or about 60% – are new.
They found that some of these mutations could lead to functional changes in the virus’s spike protein – a specific structure on the virus envelope that allows corona viruses to bind to human cells. Computer simulations predict that these mutations will increase infection.
To verify the theory, Ms. Li and her colleagues looked at cells with different mutant strains. The most active strains can produce about 270 times more virus than the weakest. These strains also kill the fastest cells.
It was an unexpected result from the study of fewer than a dozen patients, indicating that the true diversity of virus strains has not been underestimated, Li wrote in the article.
Mutations are genes different from the first strain isolated in Wuhan, where the new strain of corona virus was first detected in December 2019.
This corona virus changes at an average rate of about one mutation per month. By April 20, more than 10,000 strains were sequenced by scientists worldwide, including more than 4,300 mutations, according to the China National Biological Information Center.
However, most samples are sequenced according to the standard approach to give the fastest results. For example, the gene was read only once and there were still gaps.
Professor Li’s team uses a more sophisticated method called super-depth accountability. Each block of the viral genome has been read more than 100 times, allowing researchers to see that changes may have been ignored in a conventional approach.
The researchers also found three successive changes – called tri-nucleotide mutations – in a 60-year-old patient, a phenomenon thought to be rare. Usually genes mutate at one place at a time. The patient had been in hospital for more than 50 days, much longer than other Covid-19 patients, and even his waste was contaminated with live virus strains.
“Investigating the functional impact of this tri-nucleotide mutation will be interesting,” Li and colleagues said in the paper.
Professor Zhang Xuegong, head of the bioinformatics department at the National Laboratory of Science and Information Technology at Tsinghua University, said super-deep sequencing could be an effective strategy for tracking mutants. virus variable.
“This method can bring some useful information,” he said.
However, this method can be much more time consuming and costly. It is not likely to be applied to all models.
“Our understanding of the virus is still quite shallow,” said Zhang. Questions such as where the virus comes from, why it can kill some healthy young people while not causing symptoms that can be detected in many others still give scientists a headache.
“If there is a discovery that disrupts common sense, then don’t be surprised.”