Long-awaited Aids vaccine trials to get under way

AN AIDS vaccine trial that will infuse people with antibodies known to neutralise 85 percent of HIV strains will begin in southern Africa, the US and South America within months.

“We are entering the most exciting period, a golden era of HIV-prevention research that has taken us 30 years to get to,” said SA Medical Research Council president Dr Glenda Gray, announcing the trial.

The vaccine will inject people with “broadly neutralising antibodies” (bNA) that have been isolated by the US National Institutes of Health, based on decades of research on HIV-infected people who have been able to hold the virus in check.

Because HIV mutates so fast, scientists have pinned their hopes on bNAs that are able to neutralise a large number of strains at a time, rather than one or two strains.

“Most vaccines try to educate the body to produce an immune response (and develop antibodies), but in this trial you will be given the neutralis- ing antibodies right away,” said Dr Larry Corey of the HIV Vaccine Trials Network (HVTN).

The vaccine will be tested on gay men in the US and South America from next month and women in sub-Saharan Africa from January.

At least seven South African trial sites will be involved, and HIV-negative women aged between 18 and 30 will be recruited.

The trial participants – about 3 900 globally – will each get a half-hour intravenous infusion via a drip with the special antibodies every two months for 20 months.

“We are very optimistic. These neutralising antibodies have been able to prevent the infection of almost every virus. But we have learnt never to underestimate your pathogen,” said Corey.

The trial will be the main topic of discussion at the HVTN full group meeting that began in Cape Town today.

Malawi, Zimbabwe, Zambia and Tanzania are also involved in the trial, which Corey described as a “large worldwide collaboration”.

“It takes a world to develop an HIV vaccine,” quipped Gray, who added that she felt very excited about the prospects after years of setbacks.

Results will become available in late 2018. Alongside the neutralising antibody trial, South Africans are testing another vaccine that aims to stimulate the body to fight HIV.

This trial is a continuation of the 2009 Thailand trial (called RV144), the only vaccine ever to have elicited any immune response in trialists. After a year, it had protected 60 percent of those involved against HIV, but the protective effect had halved by 3.5 years.

The Thai vaccine has been re-engineered to use the type of HIV most common in southern Africa (Clade C), and this has been tested on South Africans. A large-scale trial of the vaccine is due to start next year.

Trial participants will get an initial vaccine, then a vaccine boost after 12 months to see whether this can maintain the body’s immune response.

“It might mean that people need to get a yearly booster shot,” said Gray, adding that the efficacy of the measles vaccine also waned over time.

“South Africa is the centre of gravity as far as HIV prevention work is concerned,” added Corey. “The Thai vaccine has been partly effective in stimulating the body’s CD4 T cells to fight against HIV, while the second is using the latest research on broadly neutralising antibodies. We are bringing both these approaches to South Africa.” – Health-e News

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