This parasite protects itself with a camouflage function in front of the immune system

How the trigger of African sleeping sickness hides in the body

The immune system of humans and animals is designed to remove defective germs from the organism. Of course, this is not in the interests of the invaders, who would like to spread unhindered. The parasite Trypanosoma - trigger of African sleeping sickness - has developed a particularly sophisticated system to protect itself from extinction by the immune system. He has a camouflage function that constantly changes its surface. So it can not be recognized by the immune system.

Researchers at the Ludwig-Maximilians-Universität München have succeeded in sequencing the complete genome of the parasite Trypanosoma. They have explained how the parasite manages to escape the immune system in the long term. A clever stealth strategy makes him virtually invisible to the immune system. So the germ reaches a permanent infection in its host. The study results were recently published in the renowned journal "Nature".

Amazing: The parasite Trypanosoma brucei can constantly change its surface structure and is thus not recognized by the immune system. This allows him to spread unhindered in the host. (Image: fotovapl / fotolia.com)

Changing surface structure

As the researchers report, trypanosomes are able to constantly change their surface structure. For this they can activate or deactivate certain proteins. In this way you can generate 2000 different surface variants. Due to the surface structure, the immune system assesses whether an organism should be fought or not. The system needs a certain amount of time for this assessment. Due to the constant change, the immune system can not recognize the parasite as foreign and consequently it is not combated.

Which diseases can the parasite cause??

Trypanosomes can infect the blood of various vertebrates. In most cases, it is transmitted by insects such as the tsetse fly. In cattle, the pathogen can cause the animal disease Nagana and in humans the often fatal African sleeping sickness. Symptoms include fever, chills, swollen lymph nodes, headache, body aches, edema and itchy rashes. If the parasite infects the brain, which can take weeks to years, it leads to sleep disorders, inner restlessness, irritability and personality disorders. Later on, epilepsy, speech and coordination disorders and chronic fatigue are added. Ultimately, those affected fall into a coma, which usually ends in death.

The sublime ability to transform form

"We are particularly interested in how this genetic variability is regulated," explains study leader Professor Nicolai Siegel in a press release on the study results. The researchers have decrypted the entire genome of the parasite Trypanosoma brucei and arranged it in three dimensions. The team was able to identify the proteins responsible for the camouflage function. These protein variants are located in the nucleus at the same sites where the genes encoding the surface proteins are located. By removing certain proteins from this complex, the entire three-dimensional structure of the DNA of the parasite changed.

New strategies to combat

"A better understanding of these defense mechanisms is also important for the study of other diseases," the researchers write. In the constant struggle between the host's immune system and the intruder, numerous other germs have developed similarly effective strategies. As examples, the scientists mention the malaria pathogens, Candida intestinal fungi and many types of bacteria. (Vb)