08 March 2016 - PRESS RELEASE

How viral diseases can become chronic

Many viral diseases tend to become chronic - including infections with the HI virus. Scientists from the DZIF site Bonn-Köln and from the TU München have now identified an immune factor which is partially responsible for this. The results are being published in the renowned journal "Nature Immunology".

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HI virus particles© CDC/A.Harrison; Dr. P. Feorino

The HI virus triggers the immunodeficiency disease AIDS. The infection has a chronic course - the immune system is not able to get rid of the pathogen. This is due among other things to the fact that the virus directly attacks and destroys certain immune cells known as helper T cells.

However, many helper T cells are not affected by the virus at all. Nonetheless their function is impaired in the case of AIDS. They remain silent and do not, as normally, activate the body´s defense troops. But why is that?

Scientists of the Universities of Cologne and Bonn could show that in chronic inflammation, the immune function of the helper T cells is inhibited by various signaling pathways. These signaling pathways in turn are apparently controlled by a single molecule known as tumor necrosis factor (TNF).

This factor appears to be responsible for the weak immune response. Scientists of the University of Bonn got this result by investigations in mice. They investigated mice suffering from a chronic viral infection similar to an HIV infection and inactivated the TNF molecule in them. As a result, the helper T cells worked normally once again. After ten days, the animals had completely eliminated the virus; they were healthy.

The results may establish new therapeutic options in the medium term. Thus there are drugs which inhibit the effect of TNF. These TNF blockers are used in the treatment of autoimmune diseases such as rheumatism, for example. They are to prevent defense cells from attacking the body itself. Whether these TNF inhibition could be useful in chronic virus infections, scientists will find out in further studies.

Press Release University of Bonn

Publication

Tumor necrosis factor impairs CD4+ T cell-mediated immune control in chronic viral infection

Nature Immunology (2016); DOI: 10.1038/ni.3399



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