Measles: Researchers Decipher the Dangerous Consequences of Viruses 2

Measles: Researchers Decipher the Dangerous Consequences of Viruses

After measles infection, children are more susceptible to other diseases. Scientists have now discovered the reasons.

Outbreaks sometimes also provide a great opportunity for a cure: in the Netherlands, in 2013, she was in the Orthodox Protestant community, vaccination rejects more than 2600 people with measles o. Before the outbreak, doctors had taken blood samples from dozens of children between the ages of 4 and 13 years.

About two months after their recovery, they were again taken for blood. Since then, researchers have used specimens to study measles infections and their effects. Because the effects of the virus on the immune system have so far been poorly understood.

To date, highly contagious measles is considered a harmless childhood disease in many places – in the opinion of many experts wrong. Although infection, which includes colds, fever, conjunctivitis, white spots in the mouth and skin rashes, it does not cause major acute problems in most children. But sometimes it can be a complication deadly the end.

Measles: Children were more susceptible to the disease

Because measles weakens the immune system
not only during the illness but also after it. This could increase susceptibility to bacterial superinfections, writes the Robert Koch Institute (RKI). These include, for example, bronchitis, middle ear and lung infections and – especially feared – post-infectious encephalitis. To this Brain inflammation RKI accounts for about 0.1 percent of cases, with 10 to 20 percent of patients dying.

Now, two international research teams are reporting that the long-term effects of the infection are even more serious. "The symptoms of measles may just be the tip of the iceberg," says Michael Mina, one of the researchers at the Howard Hughes Institute of Medicine in Boston. The team analyzed blood samples taken from, among others, 77 children in the Netherlands before and after measles infection.

Researchers examined the blood for antibodies against viruses and bacteria,
who have formed the immune system after earlier contact with relevant pathogens such as influenza, shrimp or pneumonia. Result: Depending on the severity of the disease, between 11 and 73 percent of the antibody repertoire disappeared after the disease. In contrast, the measles vaccine had no immunocompromising effect.

"Imagine being immune to pathogens, like a book you have with you that contains photos of criminals who have punctured a lot of holes in them," Mina explains in a communication with Harvard Medical School. "If you saw a criminal, it would be much harder to identify him, especially if holes affect important facial features like eyes or mouth."

This is the clearest indication of immunoamnesia – one Immune memory impairmentIn a second step, the researchers analyzed the development of antibodies in rhesus monkeys, which were infected with the measles virus. In the five months after infection, monkeys lost an average of 40 to 60 percent of protective antibodies against other pathogens.

Two studies of measles lead to the same conclusion

The second part of the puzzle is provided by a second study presented in the Science Immunology journal by a team led by Velislava Petrova of the Wellcome Sanger Institute in Cambridge, UK. This team, including employees of the Paul Ehrlich Institute in Langen, analyzed B cells of the immune system responsible for the detection of pathogens in 26 Dutch children. Therefore, after infection, the diversity of these memory cells disappears for Production of antibodies are responsible.

"This study is a direct human test for immune amnesia, where the immune system forgets how to respond to previous infections," says Petrova. The possible consequences were examined by a game team previously vaccinated against the flu.

After infection with the CDV (Hundestaupenvirus) virus similar to measles, influenza antibodies are lost in the animal. The flakes were again susceptible to infection despite vaccination. "It shows that measles could help protect against other infectious diseases," concludes co-author Paul Kellam, an infectious biologist at Imperial College in London.

"Both studies come to the same conclusion with completely different methods," says Klaus Überla, director of the Institute of Virology at the University of Erlangen. "That's very convincing." Reason for impaired immune memory
probably simple: Viruses invade their host cells via a surface protein that occurs in the B and T memory cells of the immune system. destruction This type of virus-induced cells causes loss of immune memory.

Humans are the only host for the measles virus

"It has been clear so far that measles infection leads to short-term immunosuppression," explains Überla, who was not included in the studies. The number of immune cells regenerates again within a few weeks. "However, it has been clinically noticeable that children then have an increased risk of infection in the long run. So far, this has not been explained on the basis of laboratory values." The effects on the immune memory presented in the studies now provide a reason for this.

In a comment on Science Immunology, immunologist Duane Wesemann from Harvard Medical School points out the specifics of the measles virus:
"Humans are the only hosts. It causes aggressive disease with extreme contagion and causes years of immunosuppression." It is paradoxical, however, that lifelong immunity leaves the measles alone. Experts may speculate that destroyed cells of the immune system can be replaced again, but newly formed heirs lack specific memory.

It is especially important to be better measles for poor countries: "A normal child can develop a depression in the immune system and his body may be able to deal with it," says Harvard geneticist Stephen Elledge, head of the study, currently published in Science. "But children at the border – like the one with a serious measles infection – will have serious problems." He adds, "The virus is much more harmful than we thought. This makes the vaccine even more valuable."