Why some people do not get AIDS despite HIV

For the first time researchers have been able to unravel the mystery why some people do not contract AIDS despite the HIV infection. From this, further chances for a vaccine develop.

Researchers are the secret why some people despite HIV infection did not get AIDS. The key, as is so often the case, is the genes, but the results of the study also raise hope for the development of a vaccine.

HIV controllers do not get AIDS
Not all HIV-infected people fall ill with AIDS, because in about one in three hundred patients, the immune deficiency disease does not break out or the virus is successfully controlled by the body's defenses. Why these so-called HIV controllers without drugs or treatment despite HIV infection do not get AIDS, was previously a mystery to science. However, an international research team has now come to the conclusion that the reason lies in the genes and was the first to determine the genetic material, which are the basis for a successful fight against the immunodeficiency disease by the body's resistance forces.

300 gene variants make the difference
The international research team led by Florencia Pereyra from the University of Harvard, USA, has extensively studied the genome of nearly 1,000 HIV controllers and 2,600 other HIV patients in a comprehensive study and the study results in the current issue of the journal „Science“ released. The genetic analysis of the controllers revealed that they contain about 300 gene variants, which allow the immune system to recognize those cells that are infected with the AIDS virus, so that successful immune control becomes possible.

Gene variants of HL antigens crucial
The discovered gene variants so-called single nucleotide polymorphisms (English Single Nucleotide Polymorphisms) are all located on the area of ​​chromosome 6, which includes the HL antigens (human leukocyte antigen), wherein the HL antigens of HIV controllers according to the scientists especially were pronounced. In addition, the HL antigens showed changes in them, which are directly related to the production of HLA proteins. These HLA proteins are proteins that, among other things, bind fragments of viruses in infected cells and present them on the cell surface so that the body's defense can recognize them as intruders. „Previous studies have (have) shown that certain genes are important for controlling HIV related to the HLA system. But they could not show exactly which genes are involved and what causes the differences in the course of the infection“, said co-author Paul de Bakker of the Brigham and Women's Hospital as part of the „Science“-Article.

The protein HLA-B fights the HI virus
„Our result does not only point to a specific protein, but even to a region of the protein that decisively influences its function“, so Paul de Bakker. In terms of the successful detection and control of the HI virus, the six amino acid gene areas required for the formation of the HLA-B protein are particularly important. For example, HLA-B is slightly different in the HIV controllers, with five of the six amino acids directly adjacent to the binding sites that receive the so-called viral peptides. „The amino acid at the HLA-B binding site affects its shape and structure and is likely to make some peptides more effective while others do not“, Paul de Bakker explained „Science“-Items. And his research colleague Bruce Walker, head of the Ragon Institute, added: „Of the three billion building blocks in the human genome, only a handful make the difference between those who remain healthy despite HIV infection and those who develop AIDS without therapy.“

Hope for HIV remedies
The findings of the researchers could advance the science in the search for a cure for AIDS far, so the unanimous reaction of the experts on the „Science“-Publication. But „There is still a long way to go before we can translate these findings into therapy for patients or the development of a vaccine“, stressed Bruce Walker. The expert emphasized, however, at the same time that the research with the results „nevertheless a big step forward "(fp, 05.11.2010)

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Image: Marcel Rolfes