杏吧原创

Studying the immune cells of people who can keep HIV under control in their bodies has yielded new insights that might enable all people with HIV to do the same, acting as a functional cure.

Most people with HIV keep the virus under control with anti-retroviral drugs because we don鈥檛 yet have a reliable treatment for eliminating the virus from the body. If a person stops taking these drugs, dormant virus can re-emerge and re-infect other parts of the body.

But around 0.5 per cent of people with HIV have immune systems that are naturally able to keep the virus in check without any help from anti-retroviral drugs. Previous studies suggest that genetics plays a role in this, and that such people have immune cells called T cells that are more effective at killing infected cells in the blood, and keeping the virus under control in body tissues.

Now Stephanie Gras, of Monash University in Australia, and her colleagues have found that these people 鈥� known as 鈥�elite controllers鈥� 鈥� have a particular structure on the surface of their T cells that seems to be involved in this.

Super sensitive

Studying 15 elite controllers, the team found that they have a particular protein on the outside of some of their T cells that can recognise and bind to a specific fragment of the HIV virus. This protein receptor is far more sensitive at binding infected cells than any others ever studied.

Once T cells have detected a cell that is infected with HIV, they destroy it. But HIV itself infects a type of T cell, known as CD4. Until now, we thought a different type of T cell 鈥� called CD8 cells 鈥� were the best at killing infected CD4 cells.

Surprisingly, Gras鈥檚 team discovered this isn鈥檛 the whole story in elite controllers. The special receptor protein is found only on their CD4 cells, and the team found that in elite controllers, these cells are able to find and kill other CD4 cells that have become infected.

Arming immune cells

In lab tests, the team took CD4 and CD8 cells from people who don鈥檛 have HIV, and genetically modified them so that they carried the super receptor. Both became very effective at killing HIV-infected cells in a dish.

Gras says it therefore might be possible to take immune cells from people who aren鈥檛 elite controllers, equip them with this receptor, and give them back. These fortified cells might then allow patients to control the virus with less need for drugs. 鈥淭he first step is to show we can do this in mice, then in larger animals,鈥� she says.

鈥淯nderstanding how some individuals successfully control HIV is of major importance to finding a cure, or a way to safely stop long-term treatment,鈥� says Sharon Lewin, of the Peter Doherty Institute for Infection and Immunity in Australia.

鈥淲e hope our work will help provide new avenues for a cure against HIV,鈥� says Gras.

Read more: Setbacks force HIV researchers to focus on remission, not cures