Madrid
Updated:
Keep
A Spanish study reveals a different response to infection in minority subpopulations with certain genetic mutations and more limited immune capacity.
An investigation carried out by a team from the
National Center for Microbiology (CNM) of the Carlos III Health Institute (ISCIII) exposes the possible risk of immune escape in minority populations whose genetic characteristics may reduce their ability to fight primary SARS-CoV-2 infection.
The work studies the cellular response mediated by CD8+ lymphocytes, immune cells that play a central role in a first natural infection −that is, the first time the infection is suffered−, and not the protection induced by vaccines, which, as two recent studies from the same center concluded, are effective once morest omicron and other variants of this coronavirus.
So the people who do not have these mutations, have passed the disease and, in addition, are vaccinated, they would not have a greater risk. These results are published today in the journal «
PLOS Computational Biology».
Research is especially useful for obtaining new understanding of the response to contagion in groups with limited cellular responses, such as some small Sub-Saharan and Far Eastern subpopulations. People from these subpopulations might be at greater risk of a first SARS-CoV-2 infection if they do not have the effective extra antibody response generated by the vaccines.
The study reveals how massive computational analysis of virus genomes and human genetics can reveal which people or population groups are at greater risk of this infection evading cellular immunity even with few mutations.
For this they were used identification algorithms of epitopes −the parts of the virus recognized by the immune system− dependent on human variants of the genes (or alleles) of class I histocompatibility, and how mutations invalidated these epitopes in a human allele-dependent manner.
Worst ‘cards’ to fight primary infection
Antonio Javier Martín Galiano, scientist at the
CNM and lead author of the study, explains: “ Genetic differences between human populations are sometimes significant, which may cause the cellular pathway of the immune system to respond differently to viral infections.”
“Viruses like SARS-CoV-2 they don’t usually mutate as much enough to completely evade the cellular response in most of the world’s population, but sometimes they can take advantage of specific limitations in some subpopulations, “adds the expert.
The presence of certain viral mutations would further reduce cellular immunity in these individuals, who might still have the so-called humoral immunity −generated by antibodies−. “We can say that these people, with certain genetic characteristics, have worse starting cards to defend themselves once morest infection, even when they are in good initial health,” says Martín Galiano.
Localized viral mutations facilitate presence of escape epitopesthat is, the parts of the virus that the immune system recognizes to try to stop the infection increase its ability to evade that recognition and, therefore, hinder the effectiveness of the defenses.
Therefore, despite the very low probability that SARS-CoV-2 mutations will cause the virus to evade the immune system reaction in the vast majority of the world’s immunocompetent population, there are small towns in which certain viral mutations might be selected, which would increase the risk of local outbreaks with a worse prognosis.
“This type of work confirms that the integration of information genomics, geographic and immunoinformatics facilitates the surveillance of variants that may affect both the world population and small subpopulations”, concludes the Spanish researcher.
