14 March 2017

Immunotherapy might keep HIV in check

What if your body's natural defences could combat HIV? A new study found that immunotherapy might be able to help keep the Aids-causing virus in check.


Immunotherapy was recently described as the "next frontier in cancer treatment" by Dr Daniel Vorobiof, a medical oncologist and director of the Sandton Oncology unit. But a recent study has proven that this pioneering therapy also has potential to treat and prevent other diseases. 

Stats SA estimates that in 2016 there were seven million HIV positive people in South Africa, and reminds us that a large proportion of South Africans are growing old either infected or affected by HIV and Aids.

Elusive treatment

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 US National Institutes of Health.

The study was published in Nature.

Animal studies not always reliable

"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 defences, 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 neutralising antibodies. These antibodies bind to different sites of the virus and work together to prevent it from causing damage, the study authors said.

Virus virtually undetectable

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.

77% success rate

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.

Read More:

Immunotherapy: weapon against advanced cancer

Immunotherapy cancer trial cures 90% of participants

SA can save billions with new HIV drug combination


Ask the Expert

HIV/Aids expert

Dr Sindisiwe van Zyl qualified at the University of Pretoria in 2005. She is a patients' rights activist and loves using social media to teach about HIV. She is in private practice in Johannesburg.

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