Measles limits immune system's ability to fight off other infections, studies suggest

Grant Boone
November 8, 2019

Researchers knew that measles eliminates B cells in the immune system that form its memory. About 20 percent of people in the USA who get infected with measles require hospitalization, according to the CDC, and some experience well-known long-term consequences, including brain damage and vision and hearing loss. The hypothesis was that, somehow, a measles infection lowers the general efficacy of a person's immune system for a number of years after they recover from the acute illness.

A new analysis of 77 unvaccinated children from the Netherlands carried out by an worldwide team of researchers led by scientists at Harvard has found that the virus erases the body's memory of previous pathogens. During the Science study, some children quickly regained new antibodies to fight off staph infections, influenza and adenoviruses, the family of viruses that cause sore throats and pneumonia.

The lead author and professor of genetics at Brigham and Women's Hospital and Harvard Medical School in Boston say that the measles virus is furthermore deleterious than previously thought.

The only way to prevent measles from erasing immune memory, Mina says, is the obvious one: Prevent cases by vaccinating.

In fact, before the measles vaccine was introduced in the 1960s, an estimated 50% of childhood deaths may have been associated with infections that kids caught after surviving a bout of measles, according to a 2015 study published in Science.

Two investigations of the immune systems of unvaccinated children before and after the measles infection revealed the virus can cripple immunity against viruses and bacteria long-term. "We've found that measles infects memory cells".

This "immunological amnesia" was then tested in ferrets, showing that infection with a measles-like virus reduced the level of flu antibodies in the animals that had been previously vaccinated against flu.

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Professor Colin Russell, senior author from the University of Amsterdam, Netherlands, said: "For the first time we see that measles resets the immune system and it becomes more baby-like, limiting how well it can respond to new infections".

Wesemann highlights the Science paper's finding that people who had gotten the measles vaccine showed increased immune strength. In addition, they have hypothesized that the extended protective effects of it come from the prevention of measles infection. But in the past two decades, a new, reverse explanation has begun to emerge: What if measles infections were damaging the immune system? The researchers found that the disease wiped out 11 to 73% of the antibody repertoire across individuals two months after measles infection, severely compromising immune memory of various infectious agents even after recovery. Which cells in the body to have a yeast infection and used later, to create a new infection to deal with. In 2017, 110,000 people died of the infectious disease.

Sadarangani said when he speaks to parents who have concerns about measles, some ask about complications that mostly occur in the few days after measles infections.

"Imagine that your immunity against pathogens is like carrying around a book of photographs of criminals, and someone punched a bunch of holes in it", said Michael Mina, one of the study's primary authors, in a Harvard Medical School press release.

Since measles figures have experienced a rebound in recent years due to the decline in vaccination - when both doses protect 99% against infection -, and the World Health Organization (WHO) has warned of a new The epidemic wave in countries such as the United Kingdom, Greece, Albania and the Czech Republic, this work is especially relevant.

The European work, led by Velislava Petrova of the Wellcome Sanger Institute at Cambridge University, looked at the effect of the measles on B cells, which generate antibodies. The findings also serve as a reminder that this year's record-breaking measles outbreaks in the USA will have lingering effects, Schaffner added.

"You can be in an accident and you could have a head injury and you could lose your memory", Elledge said. In other words, while measles survivors struggle to defend themselves against other pathogens, their bodies can fend off a repeat attack by the measles virus itself. And if these are the consequences of measles in a high-income nation where death from the virus is rare, it's even more important this research be conducted in places where the disease is commonplace, he says. This would leave them vulnerable against infectious diseases they had previously been immune to.