The International AIDS Vaccine Initiative (IAVI) and Scripps Research have recently announced the results of an important Phase I clinical trial. The researchers tested a new vaccine approach designed to prevent HIV infections by stimulating the production of rare immune cells. These cells are needed to create the right antibodies to fight HIV.
The trial saw 48 participants divided into a low-dose group or a high-dose group. They received either the vaccine candidate or a placebo in two doses two months apart. Of those who received the vaccine, 97 percent had developed the right immune cells to respond to an HIV infection.
“This study demonstrates proof of principle for a new vaccine concept for HIV, a concept that could be applied to other pathogens, as well,” Dr William Schief, a professor and immunologist at Scripps Research and executive director of vaccine design at IAVI’s Neutralizing Antibody Center (NAC), whose laboratory developed the vaccine, said in a statement. “With our many collaborators on the study team, we showed that vaccines can be designed to stimulate rare immune cells with specific properties, and this targeted stimulation can be very efficient in humans. We believe this approach will be key to making an HIV vaccine and possibly important for making vaccines against other pathogens.”
The results were presented at the International AIDS Society HIV Research for Prevention (HIVR4P) virtual conference in February. The team has been looking to stimulate the body to create broadly neutralizing antibodies or bnABs, specialized blood proteins that can attach themselves to the spikes on the surface of HIV. This is an immune response that can neutralize diverse strains of the virus.
“We and others postulated many years ago that in order to induce bnAbs, you must start the process by triggering the right B cells — cells that have special properties giving them potential to develop into bnAb-secreting cells,” Schief explained. “In this trial, the targeted cells were only about one in a million of all naïve B cells. To get the right antibody response, we first need to prime the right B cells. The data from this trial affirms the ability of the vaccine immunogen to do this.”
This priming approach would be the first step in a series that would allow an individual to have developed an immunity against the disease. And the team believes that the priming can be used as a starting point in vaccines that fight off different strains of influenza, as well as dengue fever, Zika, hepatitis C viruses, and even malaria.
The clinical trial, known as IAVI G001, is a fantastic result. The researchers are partnering with the biotechnology company Moderna (of the COVID-19 vaccine fame) to develop and test an mRNA-based vaccine that produces this immune response.