Vorlesen Vaccinations have been used mainly for prophylaxis. But in the future there could also be so-called therapeutic vaccinations. The aim of such a treatment is to help the immune system and thereby fight chronic infections. The first diseases to be treated with the procedure include HIV and Hepatitis B. Vaccination for prevention is now taken for granted: with the help of an inactivated pathogen or a part of it, the immune system is faked an infection, to which it reacts with the formation of defense mechanisms. If the organism later actually comes into contact with the pathogen, he immediately has the right weapons and can ward off the disease effortlessly. This principle of prophylactic vaccination dates back to 1796 and was discovered and developed by the English physician Edward Jenner. About 90 years later, his French colleague Louis Pasteur extended the concept to include the so-called post-exposure prophylaxis: a vaccine can prevent the disease even if it occurs after the pathogen has entered the body, Pasteur notes.

This discovery led to another idea, the so-called therapeutic vaccination: In this case, the immune system of patients with a chronic infection with the help of a vaccine under the arms. The physicians do not, as usual, active ingredients to lower the number of pathogens. Rather, they are trying to boost the response of the immune system so much that it can cope alone with the pathogens.

The principle behind it: After an infection, the body reacts to certain marker molecules on the surface of the pathogens and forms many special immune cells, the so-called T and B lymphocytes, which fight the invading pathogen. However, if this fight lasts too long, as is the case with chronic infections, the immune system is exhausted. The number of defense cells decreases more and more, until the immune system is finally no longer able to control the number of pathogens.

At this point, the therapeutic vaccine begins: Using genetically engineered, harmless to the body viruses, the recognition molecules of the pathogens are re-introduced into the body and thus provoke a renewed acute immune response. The body gets the infection back under control and an outbreak of the disease is prevented. display

At some point, the scientists hope, the therapeutic vaccine could boost the immune system so that it can completely eliminate even the most persistent pathogens in the body. So far, however, it is far from being: "Getting the virus away is not possible at the moment, " explains Antonio Cosma to ddp. The scientist works at the Research Center for Environment and Health (GSF) in Munich on the development of a therapeutic vaccine for HIV infections.

The Munich researchers have set their goals significantly lower: they hope to eventually be able to replace with their vaccine, the antiviral therapy for HIV infections, which has strong side effects and, especially in the long-term use, is extremely expensive. They were also able to record their first successes: "In our first clinical trial, we vaccinated ten HIV-infected patients three times each, " says Cosma. "We were able to show that the vaccine actually caused a reaction of the immune system in the participants". Cosma and his colleagues do not yet know if this activation is sufficient to control the infection. "This will be shown in the next part of the study, which is just starting now."

However, therapeutic vaccination can not only be used in HIV. Even with other chronic infections such as hepatitis B, there are already first results, as the journal "Science" reports in a focus. Hepatitis B is one of the most prevalent infectious diseases with about 200 million carriers worldwide. In two-thirds of those infected, the acute infection becomes chronic, leading to chronic hepatitis, cirrhosis, or even liver cancer. However, in infants infected with their infected mothers, therapeutic vaccination prevents the onset of these diseases in 85% of cases, Science reports.

However, even if these first results appear promising, the new approach is still no alternative to the currently applied therapies. This is also completely clear to Antonio Cosma: "The method could be an alternative - if it ever works."

ddp / bdw - Ilka Lehnen-Beyel

© science.de

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