An experimental HIV vaccine based on mRNA has shown success in mice and monkeys in a study conducted by scientists at the National Institute of Allergy and Infectious Diseases (NIAID), Moderna, and other institutions.
This is promising news for the more than 38 million people living with HIV, or human immunodeficiency virus, which causes AIDS.
While AIDS is no longer a fatal disease as long as the patient continues drug treatment, which can be expensive, cause side effects, and lead to the development of a drug-tolerant virus, such vaccines have the potential to bring an end to the AIDS pandemic.
The most recent research, published in Nature Medicine, demonstrated that the vaccine was safe and elicited the expected antibody and cellular immune responses against an HIV-like virus.
"Despite nearly four decades of effort by the global research community, an effective vaccine to prevent HIV remains an elusive goal," explained NIAID director and co-author Anthony Fauci, in a statement. "This experimental mRNA vaccine combines several features that may overcome shortcomings of other experimental HIV vaccines and thus represents a promising approach."
The vaccine is based on messenger ribonucleic acid (mRNA), which was also employed in two successful and effective COVID-19 vaccines, Pfizer-BioNTech and Moderna. mRNA COVID vaccines operate by giving cells genetic instructions to manufacture the coronavirus spike protein, which educates the immune system to be ready for the actual virus.
In a similar fashion, the novel experimental HIV vaccine delivers coded instructions for two HIV proteins called envelope (Env) and another called Gag. The two proteins are produced by muscle cells in an infected animal, which produces virus-like particles with numerous copies of Env on their surface. These particles are not infectious or disease-causing, but they can induce an immunological response to HIV.
When compared to unvaccinated animals, rhesus macaques who got a priming shot followed by several boosters had a 79 percent lower per-exposure risk of infection by the simian-human immunodeficiency virus (SHIV). And despite the large dosages, the vaccinations were determined to be safe, causing only minor, transient side effects such as lack of appetite.
After a year, it was discovered that all inoculated macaques had neutralizing antibodies against different HIV strains, therefore the researchers are currently modifying the techniques to increase the quality and quantity of vaccine response. They will proceed to early-stage human studies if they are shown to be safe and effective. And meanwhile, in Japan, another team has developed a vaccine that was able to kill a type of HIV in macaques during an early trial, and it could start human testing within just five years.