SA prepares to test new AIDS vaccine targeting multiple strains

SA has begun enrolling women in a clinical trial to test an experimental HIV vaccine developed by Johnson & Johnson subsidiary Janssen Pharmaceuticals, which scientists hope will offer protection against multiple strains of the disease.

Over the coming months 2,600 HIV negative sexually active volunteers will receive the candidate vaccine or a placebo, and scientists will compare the infection rates between the two groups over three years.

Twenty clinical trial sites will be located in SA, and others are planned for Malawi, Mozambique, Zambia and Zimbabwe pending regulatory approval, said the study’s co-chair, Kathy Mngadi, a senior scientist at the Centre for the AIDS Programme of Research in SA (Caprisa).

It was important to test HIV vaccines in the communities most in need, she said, noting that 43% of the 1.8million new HIV infections in 2016 took place in eastern and southern Africa, with women and girls disproportionately affected. The announcement of the trial has been timed to coincide with World AIDS Day on Friday, December 1.

Volunteers will receive four shots in total, in a "prime-boost" design. Their first two shots will contain HIV gene fragments carried by a harmless adenovirus vector called ad26. This will be followed by two booster shots containing the prime vector along with an HIV protein called clade C gp140 and an aluminium phosphate adjuvant that enhances the body’s immune response to the vaccine.

This "mosaic" immunogen vaccine design is expected to induce an immune response in volunteers that will protect them against a wide variety of HIV strains, said Mngadi.

"I am cautiously opt that it will push the field forward," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health (NIH). Even a 50% effective HIV vaccine could change the trajectory of the epidemic, if it were combined with other preventative tools such as pre-exposure prophylaxis and treatment as prevention, he said.

SA is already running another, much larger HIV vaccine trial, called HVTN702, which is testing the efficacy of an improved version of the shots used in the Thai vaccine trial RV144. Although RV144 was the first candidate vaccine to show any effect against HIV, it provided such modest protection that it was deemed unviable.