Getting measles ‘resets’ the body’s immune system, eliminates immunity memory

Henrietta Brewer
November 1, 2019

During the outbreak, five of the children managed to avoid infection, but the other 77 contracted the virus. The vaccine's emergence cut measles cases by 80% between 2000 and 2017 and is credited with saving 21.1 million lives. How could a single vaccine be protecting children from all these other pathogens?

Measles might suppress infected people's immune system for two to three years, making them susceptible to other diseases, one 2015 report from study coauthor Michael Mina suggested.

De Swart's on research results were published previous year in Nature Communications and since then he has been involved with the worldwide research groups.

"The average kid might emerge from measles with a dent in their immune system and their body will be able to handle that", said Elledge. "They both provide the same big-picture result-i.e., that it does". The authors, from Harvard University, noted the children studied had been healthy and well-nourished before contracting measles, and the impact on malnourished children in parts of the developing world is likely greater still. The findings echo those of a previous study that looked at thousands of children in the United Kingdom and USA and found that those who had gotten measles were more likely to get additional infections and require prescriptions than their vaccinated counterparts, an effect that lasted up to 5 years after measles infection.

Antibodies are a key component of the immune system and are produced by B cells.

The authors of the Science Immunology study examined the children's white blood cells, namely, a type of white blood cell called a B-cell.

These "memory" cells clone themselves, to create a vast army which can fight infections if they strike.

"He just sent a one-line sentence that said: 'It's amusing, we saw a big drop in antibodies to everything other than measles, '" Mina says. They can directly destroy invaders by glomming on in huge numbers, but they also attract other immune cells to the pathogen, spurring an even larger response. After recovering from measles, the youngsters were left with plenty of antibodies against that virus - but ones they'd previously harbored against other germs had plummeted.

The technology tracks antibodies to thousands of viral and microbial antigens in the blood.

Researchers took blood from 26 unvaccinated children before they fell ill with measles and around 40 days afterwards.

The research showed that measles eliminated between 11% and 73% of children's protective antibodies, the Guardian reported.

"And it takes some time".

Much of the immune system's power comes from its flexibility. It's an effect researchers refer to as "immune amnesia". In addition to being a powerful tool for self-defense, these minute genetic changes give each receptor a specific identity - a receptor that binds to chicken pox has a slightly different genetic signature than one that binds to influenza, for example.

" a direct demonstration in humans of "immunological amnesia", where the immune system forgets how to respond to infections encountered before", said Velislava Petrova of Britain's Wellcome Sanger Institute and Cambridge University, who co-led one of the studies. "Think of the measles like an accident you can prevent in a parallel way", he says. And the naive immune cells also undergo development - over the years they mutate, so that the immune system builds up a diverse collection of different weapons to fight new infections.

The studies' findings also emphasize the importance of vaccines. "We kind of have this closed loop now", Mina says. And research done in animals showed the measles virus infects immune cells, killing some. The cell count rebounds to normal levels once the infection clears, but even then, the affected person may remain immunosuppressed for years afterward - basically, the measles virus transforms people into sitting ducks for other infectious diseases. Children who skip the measles vaccine, known as MMR, and become infected with measles may actually need to be revaccinated for previous diseases, he says.

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