Washington (AFP)
Like the AIDS virus, but faster, the measles virus attacks the immune system, according to a study published in Science Thursday. Patients are almost as vulnerable to pathogens as a newborn, enhancing the usefulness of vaccination.
Public health professionals have previously observed that measles vaccination campaigns reduce total infant mortality. But the researchers were not sure of the biological mechanisms.
A team of researchers from Harvard, Howard Hugues Medical Institute and Erasmus University in the Netherlands analyzed the blood of 77 Dutch children infected with measles during the country's 2013 epidemic: their blood had been collected before the infection, and again two months later.
The researchers used a tool developed in the United States called VirScan, which identifies all the viruses that have infected a person before, and whose immune system remembers: HIV, flu, herpes, and hundreds of other viruses. When the body encounters a virus, it creates antibodies that remain and protect against future infections: it is the immune "memory".
The analyzes showed that measles eliminated between 11 and 73% of protective antibodies in children.
Measles "resets your immune system and returns it to a more naive state," says Harpard epidemiologist Michael Mina, co-author of the study.
To return to a high level of antibodies and rebuild their defenses, "they must be re-infected by pathogens, such as newborns who take a lot of risk in the early years of their lives," says Michael Mina.
Unlike HIV, immune defenses are weakened much more quickly, and they also rebuild faster, says the researcher.
The study, supported by tests on macaques and another analysis published Thursday in Science Immunology, shows that the danger of measles exceeds the only risks related to infection.
"The virus is far more deleterious than we thought, making the vaccine all the more valuable," says Stephen Elledge, a geneticist who developed the VirScan tool with colleagues.
© 2019 AFP