Scientists explore the role of immunodeficiency in the production of Covid-19 mutants

Who is Zero Patient with Omicron Variant?Detected first time of South AfricaThe variant, formally known as B.1.1.529, has raised urgent concerns in the international community.Indeed, an unprecedented number of mutations in Omicron – more than 30 compared to the original strain This coronavirus – Presents two potential threats. It can be particularly contagious and can prove resistant to existing vaccines.

Governments around the world have set out to tighten restrictions to stop the spread of Omicron, but scientists are tracking the origin of the “super mutant” variant to understand how it happened. Has begun.

In the theory proposed, some researchers are investigating mutations that appear in one infected patient with a weakened immune system.During the months, for example, during the emergence of mutants of greatest concern in patients suffering from cancer, awaiting organ transplants, or living untreated, and the weakened immune system. Studyed the possible related effects of HIV..

“If the patient has a weakened immune system, the virus remains in the system for a very long time, sometimes months, compared to just a few days for the average person,” said CNRS and the Cochin Institute. Virologist Morgane Bomsel said. In Paris, told France24. “His immune system is too weak for him to get rid of the virus.”

Selection pressure

According to published research Last month’s journal Nature CommunicationsA 58-year-old man with a history of kidney disease and receiving immunosuppressive treatment after transplantation remained positive for Covid-19 for more than 6 months.

In December 2020, a US doctor revealed a similar case of a patient receiving immunosuppressive treatment who died after a Covid-19 infection that lasted 154 days. “And all the while, the virus can accumulate a whole series of mutations and create mutants,” Bonsel explained.

Covid-19-Scientist: Sequence variants are the key to slowing spread

Note that SARS-CoV-2, like all viruses, has a genetic makeup that replicates itself. However, errors can hint at themselves in the process. They are known as mutations. In most cases, it has no effect, but some can change the infectivity and pathogenicity of the virus. Therefore, variants are new versions of the virus that explain these various changes.

“In immunocompromised patients, the immune system cannot defeat the virus, but it will still fight the virus, which causes what we call selective pressure,” said Virology Professor at Sorbonne University. Vincent Maréchal told France 24.

In short, in the battle between the immune system and the virus, the latter is forced to evolve, retaining only the mutations that allow it to continue to reproduce and resist. As a result, only the most dangerous mutations, that is, mutations that can escape the neutralizing power of the antibody, remain. When a patient infects someone else, it is the virus that carries the mutation that is transmitted.

“With such an impressive number of mutations, the Omicron variant probably found its origin in immunocompromised patients,” Marechal said.

“But this is not the first time this hypothesis has been raised. It has also been proposed for UK and beta variants,” Bonsel said.

Fertile land in South Africa

South Africa, as part of that, in particular AIDS Epidemic. Seven million people live with AIDS in the country, which is 12 percent of the total population, or 19 percent of the age group 15-45.

In addition, the percentage of people actually receiving treatment is very low, only 57% in 2017. “Therefore, in countries where the (Covid-19) vaccine rate is low and the virus is widespread, the proportion of people with weakened immunity is high. It is heavy,” Marechal explained. “It’s a situation where variants can obviously appear.”

This is not the first time South Africa has detected a new Covid-19 mutant faster than anywhere else. Prior to the Omicron variant, the other two were called “South African” variants before they were renamed. First in beta, then C.1.2.

“But that can be explained in the first place by the fact that the country is doing a lot of sequencing, which makes it possible to identify variants on its soil.” Marechal explained. “It does not necessarily mean that there are zero patients (of the Omicron variant) in South Africa.”

The geographic origin of Omicron is currently unknown, and several countries, including Europe, have identified cases prior to the announcement of their findings in South Africa. September article Journal science However, it suggested that the early beta was most likely the first to appear in South Africa.

The study suggests that the first beta isolated in October 2020 was first detected in AIDS patients in Nelson Mandelabay. This process is said to have been facilitated because there are no measures assigned to AIDS treatment in the area. Indeed, the region is among the most concentrated individuals in the world who have been infected with HIV and have been deprived of appropriate treatment for HIV.

Using data analysis comparing all variants of the beta line detected worldwide, the authors of the study found that 90% of the ancestors of those variants were welcomed from South Africa. Therefore, the first column probably first appeared in Nelson Mandelabay.

The virus then spread rapidly in other South African states and then spread to neighboring countries. In March 2021, it became the predominant virus in southern Africa, as did the French overseas divisions of Mayotte and La Reunion in the Indian Ocean near Madagascar.

“Variants can be displayed anywhere”

Still, South Africa should not be called, Marechal argued. “The best thing this shines on is what happens when two pandemics occur, and we have to remember to fight AIDS in Covid-19.”

“But in the last two years, we have clearly seen that varieties can appear everywhere, from Brittany to India and the United Kingdom,” he insisted. “There are certainly a lot of factors to consider. There are still a lot of things we don’t understand about variants.”

While research continues to understand the mechanisms that work in the emergence of these variants, virologists have proposed another hypothesis. “Perhaps the variant appears more easily in certain places as a function of sociocultural and medical context,” he suggested. “In that case, we need to identify and monitor these areas in order to confirm these things in advance.”

This article has been translated from French original..