Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How HIV disables the cells’ call for help

08.07.2005


Weizmann Institute Scientists discover how an HIV protein fragment shuts down an immune response. Their finding may have implications for autoimmune disease treatment.



The HIV virus hides out in the very immune system cells that are meant to protect the body from viral infection. But how does it prevent these cells from mounting a full-scale attack against the invader? In research published today in the Journal of Clinical Investigation, a team at the Weizmann Institute of Science has shown how a part of a protein on the virus’ outer surface interferes with the cells’ normal immune response. But their work may have wider implications: this molecular fragment, which has such a devastating effect in one disease, might turn out to be an effective treatment for other disorders such as rheumatoid arthritis.

In the initial stages of HIV infection, the protein coatings of the viruses fuse with the outer membranes of T cells – immune system cells that recognize foreign invaders and alert other types of immune cell to come to the rescue. The genetic material of the virus, which is basically a strand of RNA, then forces the cell’s DNA to make copies of it. Newly minted viruses created by the host DNA later break out of the cell membrane to infect other cells. Many believed that the very act of breaking into T cells and hijacking their DNA was enough to destroy the ability of these cells to call up immune support.


But Institute scientists Prof. Yechiel Shai of the Biological Chemistry Department, Prof. Irun Cohen of the Immunology Department and graduate students Francisco Quintana and Doron Gerber thought there must be more to the story. T cells identify invaders using receptors, like security antennae, on their outer walls. A virus, especially one with its own surface equipment for seeking out specific T cells, would be hard-pressed to slip past these receptors without raising the alarm. The scientists surmised that the virus must be able to actively disable some part of the immune cell’s system.

They investigated a peptide fragment called FP (fusion peptide), a segment of the HIV protein gp41 found on the viral envelop. FP was known to play a role in the complex process in which the viral envelop fuses with the cell membrane in the initial stage of cell infection. The researchers suspected that FP, which is only exposed for a short period during this process, may have enough time to affect the immune response as well. Indeed, they found that FP locks on to several proteins on the cell walls that are involved in invoking a large-scale immune response, effectively shutting them down.

From their new understanding of how a tiny virus can gain control of the body’s immune response, the scientists made an intuitive leap. In autoimmune diseases, the same T cells that play host to HIV viruses are overactive, mistakenly attacking the body’s cells instead of foreign invaders. If the viruses use FPs to override the cells’ call for help, could their actions, which block one type of immune response without killing the cell, be applied to these autoimmune diseases? To check their theory, the research team tested FP on rats suffering from an autoimmune syndrome similar to human rheumatoid arthritis, and on cultured human T cells. As they predicted, the rats treated with FP showed a significant reduction in joint swelling and other symptoms of arthritis.

Shai points out that using FP, a tiny piece of a piece of the HIV virus, would pose no danger to patients as it lacks any ability to either infect cells or to reproduce. Rather, as the scientists note in their paper, the study of a destructive virus may contain important lessons on how to regulate the immune system. "Perhaps," says Cohen, "we humans can adopt the virus peptide to better control overactive autoimmunity."

Prof. Irun Cohen’s research is supported by the Minna James Heineman Stiftung; the Robert Koch Minerva Center for Research in Autoimmune Disease; and Mr. and Mrs. Samuel Theodore Cohen, Chicago, IL.

Prof. Cohen is the incumbent of the Helen and Morris Mauerberger Professorial Chair in Immunology.

Prof. Yechiel Shai’s research is supported by Robert Koch Minerva Center for Research in Autoimmune Disease; and the estate of Julius and Hanna Rosen.

Prof. Shai is the incumbent of the Harold S. and Harriet B. Brady Professorial Chair in Cancer Research.

Alex Smith | EurekAlert!
Further information:
http://www.weizmann-usa.org
http://www.jgordonassociates.com

More articles from Life Sciences:

nachricht New catalyst controls activation of a carbon-hydrogen bond
21.11.2017 | Emory Health Sciences

nachricht The main switch
21.11.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>