Scientists have, in a monkey model of HIV, discovered that a dual-antibody therapy can boost the immune system to effectively control the infection and prevent deadly virus from returning for an extended period.

There are more than 25 drugs to control HIV, yet the virus remains one of the world's biggest health problems. 

In the study, the researchers used two drugs -- 3BNC117 and 10-1074 -- belonging to a class of molecules called broadly neutralising antibodies, where each antibody binds to a different site of the virus, preventing its damaging effects from different angles.

"This form of therapy can induce potent immunity to HIV, allowing the host to control the infection," said Michel Nussenzweig from the Howard Hughes Medical Institute -- a US-based non-profit.  "It works by taking advantage of the immune system's natural defenses, similar to what happens in some forms of cancer immunotherapy," Nussenzweig added.

For the study, published in the journal Nature, the team analysed 13 macaque monkeys, who were inoculated with simian-human immunodeficiency virus (SHIV) and then given three intravenous infusions of the two antibodies over a two-week period.  The treatment suppressed the virus to levels near or below the limit of detection and its effect lasted for as long as six months. 

These monkeys were also able to maintain healthy levels of key immune cells after receiving the antibody infusions. In those, who did not regain complete control of the virus, the treatment helped them maintain extremely low viral loads and healthy levels of key immune cells for two to three years after infection.

Although this model does not precisely mimic human HIV infection, the findings suggest that immunotherapy should be explored as a way of controlling the virus and boosting an immune response that might be capable of controlling the infection in people. Clinical trials testing the antibody combination in humans are also underway, the researchers said.