New discovery about people who may be naturally resistant to nCoV

The study, published in the journal Nature Immunology on October 18, was led by immunologist Evangelos Andreakos, from the Academy of Athens, Italy.

According to Dr. Andeakos, the Covid-19 pandemic has been around for nearly two years, but we still know very little about it. One of the most scant data is the genetic and immunological basis of human innate resistance to nCoV.

Special phenomenon

Two people can be 99.9% genetically identical. But it's the remaining 0.1% that makes us unique. That's why some people are more susceptible to many diseases.

According to Mr. Andeakos, we don't have much information about people who are naturally resistant to nCoV, but that doesn't mean it doesn't exist. Many families have recorded this phenomenon. Most members have Covid-19, but some of them are "immune" , even though they have eaten together and had close contact in a small space.

The team recruited volunteers and genetically analyzed individuals with natural resistance to nCoV. They focused on relatives who were F0 but were not infected. Volunteers were tested for rRT-PCR and blood 4 weeks after exposure. In particular, tests looked for T cells to confirm that they had not been infected in the past. The authors recruited about 400 people.

The link between genetics and the risk of contracting Covid-19 has long been a matter of concern for many experts. (Photo: PBS).

The proportion of people with innate resistance to nCoV has not been statistically determined. However, according to experts from the Academy of Athens, Italy, some candidate genes are believed to be related to human resistance to nCoV.

A typical example is the ABO gene, discovered in a meta-analysis of 46 other studies. The total number of samples reviewed was over 50,000 people and it was determined that this gene location affects the susceptibility of the immune system to nCoV infection. However, the protective effect of the O allele is very small (an allele is a specific form of a gene, with a certain genetic function). The team of experts said that people with the ABO blood group can use the O allele to attack the core region of nCoV, thereby preventing it from entering the body.

With this discovery, the authors affirm that the work to come up with a new drug and treatment method is still quite complicated. The expert team in Italy hopes to determine the effects of the candidate genes on the rare variant, to measure whether they are effective in preventing infection.

Many times looking for answers

This is not the first time experts have questioned the genetic factor with Covid-19. In early March 2020, researchers in China hypothesized that people with blood type A are susceptible to nCoV infection. They analyzed data on 2,173 F0s, from three hospitals in Wuhan and Shenzhen (China). The team looked at the distribution of blood types in the normal population in each area, then compared it with the samples of F0s.

From this, the authors concluded that people with blood type A have a significantly higher risk of contracting Covid-19 than other blood types. Meanwhile, people with blood type O seem to have a significantly lower risk than people with other blood types. F0 with blood type O is also said to have milder, less severe symptoms.

Many studies suggest that blood type can put a person at higher or lower risk of contracting nCoV than normal. (Photo: BBC Future).

According to the study, the normal population in Wuhan has the following blood type distribution: A: 31%, B: 24%, AB: 9%, O: 34%. Those infected with nCoV have the following blood type ratio: A: 38%, B: 26%, AB: 10%, O: 25%. Similar differences were also observed in Shenzhen.

With this data, the percentages of the normal population and those infected with nCoV have some differences, but it does not mean that people with blood type O are immune to Covid-19. And not all people infected with nCoV have blood type A.

But the research has raised another question: how our blood type can change how our bodies are affected by certain viruses.

As a geneticist at the Icahn School of Medicine in New York, Jason Bobe has spent nearly a decade studying people with unusual traits that make them more resistant to diseases, from heart disease to Lyme disease. So when Covid-19 hit, his first instinct was to wonder if there were people the virus couldn't infect.

The expert's idea is to look for entire families where multiple generations have had Covid-19, but, one individual is asymptomatic. This is similar to the work that the Athens Academy team is doing.

Bobe hopes to sequence the genes of 'coronavirus immune' people to see if there are common mutations that protect them from Covid-19. If so, that could pave the way for antiviral drugs that protect against both Covid-19 and future coronavirus outbreaks. One clue is the link between blood type O and rhesus negative and a lower risk of severe disease. But the link is not yet clear.

Before Bohe, Mayana Zatz, director of the Human Genome Research Center at the University of São Paulo, Brazil, identified 100 couples in which one partner had Covid-19 and the other did not. Mayana told BBC News that when they posted a call for volunteers, they received around 1,000 emails in response, which clearly shows that this is a relatively common phenomenon.

Meanwhile, a team of experts from the University of Edinburgh studied the genomes of 2,700 F0s in intensive care across the UK and compared them with healthy volunteers. They found that people susceptible to nCoV had five genes - related to the interferon response and the ability to develop pneumonia - that were either significantly more or less active than the general population.

However, data on the relationship between genes and the risk of contracting Covid-19, becoming seriously ill, and dying still leave many unanswered questions. Research has yet to reach a final conclusion on who a person "immune to nCoV" is.