A key HIV protein appears to be linked with the ability of the virus to destroy immune system cells, and damage or mutations to that protein may help explain why some HIV-positive people never develop AIDS, according to researchers at the Mayo Clinic in Rochester, Minn., Reuters Health reports. Tests on the protein, called viral protein R, or Vpr, show that when it is damaged or entirely removed from HIV the virus is significantly less able to destroy immune system cells. A small study of long-term nonprogressors, the name given to HIV-positive people who never develop AIDS, showed many to be infected with HIV that had a particular viral mutation that affected Vpr. Although HIV was still able to slowly kill immune system cells in these patients, their bodies were able to replenish T-cell supplies quickly enough to prevent serious immune deterioration. "Since mutations in Vpr can alter the outcome of HIV disease, it is possible, if not likely, that we can develop inhibitors of Vpr that may also modify disease outcome," said lead researcher Andrew Badley.