Measles virus 'wipes out immunity to other infections'

Measles virus 'wipes out immunity to other infections'

Researchers also found that the measles virus resets the immune system to an immature state which can only make a limited repertoire of antibodies against disease.

However, many scientists still debate which hypothesis is correct.

The two studies looked into the immune systems of 77 unvaccinated children before and after a measles infection, and their results suggest this highly contagious virus infects and cripples the body's immune cells and messes with their memory.

Without these antibodies, children lose much of their immune defenses and become vulnerable to viruses they've already met and conquered.

"Measles essentially takes away their ability to efficiently protect themselves", said Michael Mina, an epidemiologist at Harvard University and co-author of the new study, published today (Oct. 31) in the journal Science.

"It would then be much harder to recognize that criminal if you saw them, especially if the holes are punched over important features for recognition, like the eyes or mouth", said Mina.

The team's current work was published simultaneously with a paper by a separate team in Science Immunology that reached complementary conclusions by measuring changes in B cells caused by the measles virus. A related Focus by Duane Wesemann describes both studies in further detail. Nikolai Petrovsky, from Australia's Flinders University, suggests this research should entirely put to bed misinformation from certain sectors of the community that result in absurd "pox parties" where parents expose children to measles in the hopes of improving the child's immune response.

"If you took the first 10 years of somebody having HIV and you squished that into a few weeks, that's the kind of memory damage and immune damage you get from measles", Mina, an assistant professor of epidemiology at Harvard's T.H. Chan School of Public Health, told STAT.

"But the other side of the coin was that maybe actually the vaccine was unmasking a much worse immunological detriment or problem associated with measles", he says.

It also prevents longer-term damage to the immune system that can lead to a resurgence of other diseases, she says.

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A two-dose vaccine has helped to slash measles cases since 2000, saving an estimated 21.1 million lives between 2000 and 2017, World Health Organization said. Widespread vaccination has slashed the death toll. The discoveries additionally fill in as an update that the current year's record-breaking measles flare-ups in the US will have waiting impacts, Schaffner included.

Peter Hotez, MD, PhD, of Baylor College of Medicine in Houston, who was not involved with the research, noted a 2015 paper on this subject, which showed that measles has a prolonged effect on host resistance that can last 2-3 years, and even can drive an increase in non-measles deaths in children. The technology tracks antibodies to thousands of viral and microbial antigens in the blood.

Using a tool called VirScan, the researchers clocked which antibodies appeared in the children's blood before and after they had measles.

A study of 26 unvaccinated children, after they had measles, found they lost large numbers of a specific type of immune cell they had built up before the disease. The researchers also compared the measurements to those of 115 uninfected children and adults. But this new analysis showed that the disease can also reduce the diversity of new immune cells, potentially impacting how someone responds to infections they've never had before.

The effect resembled what Mina had hypothesized could drive measles-induced immune amnesia.

"We know that seat belts protect against head injuries that can cause amnesia", he explains. The monkeys lost, on average, 40 to 60 percent of the antibodies that protect them from other pathogens. It's as if you had to meet the criminals missing from your book all over again, one by one - a long and risky process, during which you remain vulnerable to whatever these criminals want to inflict on you.

The authors stress that the effects observed in the current study occurred in previously healthy children.

"When we do organ transplants, you basically have to turn off their immune system", he said.

The study was supported by the Value of Vaccination Research Network, the Gates Foundation, the NIH/National Institute of Allergy and Infectious Diseases, the European Union Seventh Framework Programme, the Academy of Finland, and PREPARE Europe. He pointed out that "one of the misconceptions of measles that often fuels vaccine hesitancy is that it is a benign childhood illness".

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