Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) are getting ready to begin the first ever human trial for an HIV vaccine – one that has already shown promise in mice, guinea pigs, and monkeys. The development comes amid a series of breakthroughs in immunotherapy that have already led to progress toward vaccines for herpes, influenza, some cancers, and severe food allergies, according to IFL Science.
The study, published last week in the journal Nature Medicine, describes the technique. The vaccine targets a protein on the HIV virus, called the HIV-1 fusion peptide, that the virus uses to infiltrate the host’s cells. It was first identified as a possible focus for a vaccine in 2016, during an analysis of antibodies naturally produced by an HIV patient.
The researchers, led by John Mascola and Peter Kwong, found that the patient’s immune system was producing especially effective “broadly neutralizing antibodies” with an epitope, or binding site on the HIV virus, on the tip of the HIV-1 fusion peptide. They found that this epitope boasts properties that make it a suitable candidate to be the focus of a vaccine – it is consistent across multiple HIV strains, even as they evolve, and unlike other viral surface proteins, it’s not concealed from immune cells by additional sugar molecules.
The team then worked toward creating a protein that would elicit a high quantity of broadly neutralizing antibodies targeted to the epitope. The study tested a number of formulations of an eight amino acid protein, bonded to a carrier molecule that boosts the patient’s immune system response, in conjunction with copies of the cell-entry surface protein subunit that includes the HIV-1 fusion peptide.
In mice, the most successful formulation helped neutralize 31 percent of viruses, from a range of 208 strains of HIV from around the world. Next, experiments with guinea pigs and monkeys showed that it has the potential to work in other species – perhaps, including humans.
“Prior to this study, no vaccine regime could reproducibly elicit antibodies capable of neutralizing more than a small fraction of the diverse strains of HIV-1 that typify natural infection. So it was surprising that we could induce immune responses that neutralized up to 30 percent of HIV-1 strains in mice, guinea pigs and rhesus macaques.”
Human trials could begin as early as the first half of 2019, and could protect HIV-negative individuals from the virus.