The human immunodeficiency virus, also called the HIV virus, has become widespread since the 19805 and has infected about 34 million people so far. The infection is usually present for years or decades without noticeable symptoms until eventually the immune system is weakened so that other infections invade the body and eventually cause death.

A virus can be described as a self-replicating machine. It usually consists of just a few genes, which are surrounded by a protein capsule. The surface of this capsule has the property of binding to certain elements, the so-called receptors, of certain cells of the body, and then to convey his genes into the interior of the cell. There, depending on the type of virus, it copies its genes and sometimes incorporates them into the genome of the cells.

The infected cell cannot differentiate between its own genes and the genes of the virus, and so it activates them all. Viral genes have different functions. Some of the genes produce the building blocks of the protein capsule, while others copy and carry the viral genes into the new empty capsules. The new viruses then leave the cell and infect new cells, where the same process repeats.

Each form of virus infests only certain cells, since each virus needs specific receptors. In the case of HIV, these are the cells of the immune system. The receptors which are required by HIV viruses are CD4 and CCR5. For each of the receptors, a human gene explains to the cell how to build the receptors. About 20% of the population has a genetic variation in a CR5 gene (CCRSdelta32) and therefore produces only about half of the CCR5 receptors. This leads to a lower surface for the virus and considerably reduces the risk of infection. About 1% of the population has this mutation in both CCRS genes and is therefore very highly resistant to HIV.

Since CCRS is essential for HIV infection, a drug that blocks the CCR5 receptors has already been developed (maraviroc). Other medicines for HIV are trying to block the replication of the virus genes or to interfere in other ways in the cycle of the virus. Without medical treatment, the infection with HIV is usually fatal, within several years or decades. With drug therapy, however, HIV infection is similar to a chronic disease, and the majority of infected people have a normal life expectancy of over 70 years. Therefore, effective therapy is of great importance.

Due to genetic differences in the genes that convert drugs in the body, it is possible that certain drugs are either not activated or their efficacy is low, resulting in regular use of overdose. Therefore, a genetic matching of the conversion capability of HIV-related drugs is extremely important for optimal therapy.

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