Lab experiments with monkeys suggest that “immunotherapy” holds promise as a long-term treatment for HIV, researchers say.

Treatment with two anti-HIV antibodies right after infection might help keep the AIDS-causing virus in check for a prolonged period, according to the new study.

Despite an arsenal of HIV drugs, effective long-term treatment remains elusive because inactive versions of the virus lie in wait for an opportunity to attack the immune system, said the researchers from Rockefeller University in New York City and the U.S. National Institutes of Health.

“This [new] form of therapy can induce potent immunity to HIV, allowing the host to control the infection,” said Michel Nussenzweig, head of Rockefeller’s laboratory of molecular immunology.

“It works by taking advantage of the immune system’s natural defenses, similar to what happens in some forms of cancer immunotherapy,” he said in a university news release.

The researchers used a model of HIV infection that affects macaque monkeys. It isn’t the same as human HIV infection, however, and results of animal studies aren’t always replicated in humans.

The study involved two drugs known as broadly neutralizing antibodies. These antibodies bind to different sites of the virus and work together to prevent it from causing damage, the study authors said.

For the study, 13 monkeys were exposed to the simian HIV virus. They then received three IV treatments of the two antibodies over the course of two weeks. The treatment effectively suppressed the virus, rendering it undetectable or at nearly undetectable levels for up to six months, the researchers said.

Once treatment ended, the virus resurfaced in all but one animal.

However, months later, viral levels in six of the monkeys plummeted spontaneously and remained virtually undetectable for another five to 13 months. Important immune cells also remained at healthy levels, the study authors said.

Four other monkeys didn’t completely control the virus but kept it at very low levels for up to three years after infection, the researchers said.

Overall, the antibody immunotherapy benefited 10 of the 13 monkeys, the study found.

Further research revealed that certain immune cells — called cytotoxic T cells — are key to controlling the virus, the researchers said.

In a new experiment, the researchers are waiting two to six weeks to treat the infected monkeys since this is how long it usually takes for an HIV-infected person to be diagnosed, the study authors said.

The study was published March 13 in Nature.

More information

The U.S. Department of Health & Human Services provides more about HIV/AIDS.

Source: HealthDay