AIDS may partly be the consequence of an evolutionary accident says scientist

Apr 01, 2008

AIDS, a fatal disease in humans, may partly be the consequence of an evolutionary accident, scientists heard today at the Society for General Microbiology’s 162nd meeting being held this week at the Edinburgh International Conference Centre.

“AIDS is a deadly disease in people that is caused by human immunodeficiency virus (HIV). But similar viruses such as simian immunodeficiency virus (SIV), which infects monkeys, usually don’t cause disease in their natural monkey hosts,” says Professor Frank Kirchhoff from the University of Ulm in Germany.

Previous studies have established that one of the key differences between the way HIV-1 behaves in humans and closely related SIVs behave in monkeys is that when humans are infected with HIV-1 the immune system becomes highly stimulated. This means critical defence cells called helper T cells are continuously activated and die more quickly than usual.

The researchers found that the Nef protein of most SIVs removes a molecule from the cell surface that is critical to make T cells responsive to stimulation. This most likely limits the negative effects otherwise caused by the chronically strong immune response. However, Nef proteins in HIV-1 and its closest related SIVs lack this protective function, according to Professor Kirchhoff.

In natural SIV infections in monkeys, the ability of the Nef protein to remove a specific receptor, named CD3, from the infected cell’s surface may help the host animal to maintain a functional immune system, which means that it can still fight off other diseases. Only the Nef proteins of HIV-1 and its immediate SIV relatives do not perform this function.

“We suspect that this evolutionary loss of a protective function of Nef may contribute to the high virulence of HIV-1 in humans” says Prof Kirchhoff. “Well adapted viruses don’t kill their hosts.”

The team will examine whether SIVs carrying Nef genes artificially made incapable of limiting T cell activation might become more pathogenic in their natural monkey hosts. The group will also examine whether Nef variation among HIV-2 strains might explain differences in the rate of progression to disease in infected humans.

Source: Society for General Microbiology

Explore further: Home- versus mobile clinic-based HIV testing and counseling in rural Africa

add to favorites email to friend print save as pdf

Related Stories

Rosetta fuels debate on origin of Earth's oceans

23 minutes ago

ESA's Rosetta spacecraft has found the water vapour from its target comet to be significantly different to that found on Earth. The discovery fuels the debate on the origin of our planet's oceans.

Scalable growth of high quality bismuth nanowires

45 minutes ago

Bismuth nanowires have intriguing electronic and energy-harvesting application possibilities. However, fabricating these materials with high quality and in large quantities is challenging.

Recommended for you

Cambodia village reports mass HIV/AIDS infection

Dec 16, 2014

Cambodian health authorities on Tuesday said more than 80 people—including children and the elderly—who tested positive for HIV/AIDS in a single remote village may have been infected by contaminated needles.

Occasional heroin use may worsen HIV infection

Dec 15, 2014

Researchers at Yale and Boston University and their Russian collaborators have found that occasional heroin use by HIV-positive patients may be particularly harmful to the immune system and worsens HIV disease, compared to ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

herpesdate
3 / 5 (1) Apr 02, 2008
AIDS is a fatal disease in humans. I know there is a AIDS datig and support site www.STDromance.com

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.