That achievement, said the researchers from the Mayo Medical School and the Emory University and Vanderbilt University schools of medicine, moves science closer to identifying new approaches to HIV treatment.

Scientists have known most human cells contain a factor that regulates the release of virus particles but until now they've been uncertain about the factor's identity. The new study identifies CAML -- calcium-modulating cyclophilin ligand -- as the cellular protein that inhibits the release of HIV particles.

"This research is important because it identifies CAML as an innate defense mechanism against HIV," says senior author Emory Professor Dr. Paul Spearman. "We are continuing to work on the mechanism … 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."

The study that included Vasundhara Varthakavi, Ellen Heimann-Nichols, Rita Smith, Yuehui Sun, Richard Bram, Showkat Ali, Jeremy Rose and Lingmei Ding appears in the online early edition of the journal Nature Medicine.