Protein shield against HIV can spur new therapies

May 26th, 2008 - 2:39 pm ICT by admin  

Washington, May 26 (IANS) A protein that restricts the release of the HIV-1 virus from human cells may possibly help scientists to identify new lines of treatment for the dreaded disease. Scientists have known about a factor that regulates the release of virus particles from most human cells, but were uncertain about its identity.

Now it has been identified as a CAML (calcium-modulating cyclophilin ligand) - a cellular protein - by a team from Emory and Vanderbilt Universities and Mayo Medical School.

CAML works by inhibiting a late step in the virus life cycle that allows retention of HIV particles on cell membrane. The virus has developed a means of counteracting CAML, through the viral Vpu protein.

When Vpu is absent, HIV particles don’t detach from the plasma membrane and instead accumulate by a protein tether at the cell surface.

When the research team divested human cells of CAML in the lab, they found that Vpu was no longer required for the efficient exit of HIV-1 particles from the cell.

When they expressed CAML in cell types that normally allow particles to exit freely, the particles remained attached to the cell surface.

“This research is important because it identifies CAML as an innate defence mechanism against HIV,” said senior author Paul Spearman.

“We are continuing to work on the mechanism that Vpu uses to counteract CAML and on defining exactly how CAML leads to virus particle retention on the infected cell membrane. We hope this will lead us to new treatments.”

Findings of the research have been published in the advance online edition of the journal Nature Medicine.

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