A new study shows that injecting heat-inactivated HIV can arouse the immune system in some patients, allowing them temporary freedom from drugs. Ultimately, this approach could lead to a long-term treatment of HIV.

Researchers extracted HIV and a sampling of immune system cells (dendritic cells) from 36 patients. The researchers used heat to inactivate the HIV of 22 randomly selected patients, and then administered the patients a vaccine comprised of their own dendritic cells and their inactivated HIV. In 12 of the 22 patients, virus levels dropped 90 percent over 12 weeks.

According to study co-author Felipe Garcia, an infectious disease physician at the University of Barcelona, the combination of dendritic cells and inactivated HIV stir the immune system to attack the live virus circulating in patients' bodies. In the treated patients, the immunity to HIV diminished and virus levels increased eventually. After 48 weeks only three participants who received the experimental vaccine maintained the 90-percent drop in virus levels. The patients in the control group who received their own unchanged HIV and dendritic cells showed little benefit. Prior to the study, all participants were being treated with standard antiretroviral therapy.

Garcia suggests that a therapeutic vaccine would still be beneficial, even if it offered only long-lasting temporary effects rather than completely eradicating HIV from the body. He stated that dropping the virus down to extremely low levels may mean patients would not need drugs, would not show symptoms, and would not be likely to transmit the disease to others. He noted that people with these low levels of virus (elite controllers) already exist, in the less than 1 percent of people who have been infected with HIV for years, but whose immune systems suppress the virus.

The study, "A Dendritic Cell–Based Vaccine Elicits T Cell Responses Associated with Control of HIV-1 Replication," was published in the journal Science Translational Medicine (2013; 5 (166): 166ra2).