mRNA-based vaccines are not a new concept in immunization studies. However, the COVID-19 pandemic rapidly brought the research to a head, turning proof of concept into real vials of medicaments.
Having proved their safety and efficacy in improving immunity against the deadly SARS-COV-2 virus, researchers are now attempting to use this type of vaccine against other diseases.
This month, Moderna announced that they are beginning a phase 1 trial for their HIV-targeted mRNA vaccine. They will test two versions of the vaccine to determine the best formula, which will go on to officially become Moderna’s mRNA 1644.
During this trial, the researchers plan on enrolling 56 HIV-free volunteers between the ages of 18 to 50. The trial will run for around 10 months, during which time, the researchers will determine the vaccine’s safety and initial immune response.
The volunteers will be divided into four groups, 2 of which will receive a mix of the two vaccines and 2 will receive doses of the same formula. However, the researchers will not blind participants regarding their inoculation, as this phase isn’t intended to confirm the vaccine’s efficacy.
So how do mRNA vaccines work?
Instead of traditional vaccine concoctions that use a part of the targeted virus to trigger an immune response, these vaccines carry the virus’ mRNA. Once delivered to human cells, this mRNA causes them to express a viral protein that is alien to our immune system. This stimulates B-cell formation, eventually leading to the formation of antigen-specific antibodies called broadly neutralizing antibodies (bnAbs).
It is these HIV-specific bnAbs that researchers are trying so hard to trigger the production of through their vaccines. And recently, the International AIDS Vaccine Initiative and Scripps Research achieved this breakthrough. Their non-mRNA vaccine-induced appropriate B-cell formations in 97% of their trial participants. They used a part of the HIV called the immunogen, which Moderna will now include in their mRNA 1644 vaccine in the hopes that the synergy creates a powerful blend.
William Schief, Ph.D., a professor and immunologist at Scripps Research and executive director of vaccine design at IAVI’s Neutralizing Antibody Center
“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. 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.”