Thanks to antiretroviral therapy, HIV infection is no longer the life sentence it once was. But despite the effectiveness of drugs to manage and treat the virus, it can never be fully eliminated from the human body, lingering in some cells deep in different human tissues where it goes unnoticed by the immune system. Now, new research by University of Alberta immunologist Shokrollah Elahi reveals a possible answer to the mystery of why infected people can’t get rid of HIV altogether. Elahi and his team found that in HIV patients, killer T cells — a type of white blood cells responsible for identifying and destroying cells infected with viruses — have very little to none of a protein called CD73. Because CD73 is responsible for migration and cell movement into the tissue, the lack of the protein compromises the ability of killer T cells to find and eliminate HIV-infected cells, explained Elahi.