4 March 2014

South Africa: Scientists, Mystery Woman Unlock Path to New HIV Vaccine

Photo: Hannah McNeish/IRIN
File photo.

Known only by a number - CAP256 - one South Africa woman may hold the key to an HIV vaccine.

The mysterious HIV-positive woman has been able to prevent the virus from growing in her body by producing antibodies to fight it over a number of years.

Only one-in-five people living with HIV produce "broadly neutralising antibodies," that kill multiple types of the virus in laboratory settings, according to Dr Lynn Morris, head of AIDS research at the National Institute for Communicable Diseases (NICD).

Morris and other scientists think they could be the key to an effective HIV vaccine or even cure in the distant future.

The evolution of a killer

Known only by her clinical trial identification code, CAP256 provided multiple blood samples over the years that allowed researchers from the Centre for AIDS Programme Research in South Africa (CAPRISA) to see how her special antibodies quickly evolved to outwit HIV's protective shell and kill the virus in lab settings.

Until now, no one has understood when or how broadly neutralising antibodies arise in HIV patients. But in an article published this week in the scientific journal, Nature, South African researchers from the NICD, CAPRISA and several universities unlocked the answers in one woman's blood.

Globally, three clinical trials are already experimenting with the use of these special antibodies to kill HIV in monkeys. CAP256's antibodies will likely move into monkey trials as part of an experimental vaccine, which if successful, would precede about seven years of clinical trials in humans.

Only one HIV vaccine clinical trial, conducted in Thailand and published in 2009, ever shown even modest ability to prevent HIV infection

"Current experimental HIV vaccines do not induce those broadly neutralising antibodies and we think that's why they are only moderately effective," said Morris, who cautioned that it was but a one small step on the road to a vaccine.

The woman behind the science

"CAP256 was likely in her late 20s or early 30s and living in KZN's rural Vulindlela - the epicentre of South Africa's HIV epidemic."

Not much is publicly known about CAP256 but we do know some information from published descriptions of CAPRISA's study sample. Around 2004, CAP256 was likely in her late 20s or early 30s and living in KwaZulu-Natal's rural Vulindlela - the epicentre of South Africa's HIV epidemic.

Someone she knew probably mentioned that CAPRISA researchers were enrolling HIV-negative women like her in a new study. Like the majority of the women who enrolled, CAP256 may have been a sex worker. After joining the study, she and most likely some of her friends received HIV risk counselling and condoms but like almost 45 percent of Vulindlela's young women, CAP256 became HIV-positive.

The blood samples she continued to provide would guide South African researchers to what Science and Technology Minister Derek Hanekom has described as a "breath-through finding."

At a press conference to announce the results, Health Minister Dr Aaron Motsoaledi applauded researchers and thanked CAP256.

"Let me commend our scientists but also people with HIV and AIDS who willingly participate in research trials," Motsoaledi told Health-e. "Your selflessness in helping the world to better understand the HI virus so that we can both prevent transmission and find a cure is highly appreciated."

"I believe the solution for this HIV/AIDS conundrum lies in here on the continent of Africa... especially in South Africa seeing that we are facing the highest burden of this disease," said Motsoaledi adding that South Africa makes up 30 percent of all the people on HIV treatment globally. "Each new development emerging in this part of the world makes me very happy."

South Africa has supported HIV vaccine research for the past 15 years. Currently, 2.4 million people in the country are on antiretroviral treatment. The country is looking to boost that number to 4.6 million in the next two years.

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