discriminating. blocks a defensive HIV protein in humans but not mice.
The AIDS virus dodges the ammunition dam immune system. researchers have now discovered one of his tricks: HIV disables a host protein that would otherwise break the virus into pieces. But the virus can not stop similar proteins in mice. The discovery, published in July 11 issue of Cell provides a new idea on why HIV only infects humans and may one day lead to better animal models of AIDS.
last year scientists discovered that a protein made by HIV, called Vif, protects the virus against the host attack. But they did not know how Vif ripped this feat. Now, AIDS researcher Nathaniel Landau of the Salk Institute for Biological Studies in San Diego, California, and colleagues report that Vif locks a human protein called APOBEC3G. In the absence of Vif in virus APOBEC3G slides and outputs the bits of its inactivating DNA. HIV Vif protects against death in human cells.
Curious how mice fight HIV so easily, Landau's group checked to see if rodents have their own version of the APOBEC3G gene. They did, but the mouse protein, the researchers found, is unrecognizable to HIV defense system. He circumvented the blockade Vif, moved into the virus, and hit it out of commission.
"It is a major breakthrough" to show that APOBEC3G plays a role in the unique sensitivity of humans to HIV, says Jeremy Luban, a virologist at Columbia University. For scientists studying drugs and vaccines against HIV, "it would be a huge technical advantage" if this information could help create laboratory mice that can support HIV infection, he said. Luban but warns that such a project is not likely to bear fruit immediately, as it is likely that many other barriers that prevent HIV from infecting other species.
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