- Moderna’s mRNA vaccine technology is being used by researchers to fight HIV.
- The ultimate goal is to induce the immune system to develop antibodies that can neutralize numerous HIV strains.
- Finding a safe and effective vaccine to prevent HIV infection has proven difficult over the last few decades.
According to the US National Library of Medicine clinical trial registry, an early-stage clinical study of an mRNA-based HIV vaccine could start this month.
This vaccine candidate is based on Moderna’s technology, which was previously employed in the very effective COVID-19 vaccine.
The trial would evaluate the first stage of a multistep vaccine regimen, building on past research by the International AIDS Vaccine Initiative and Scripps Research.
The ultimate goal is to induce the immune system to develop antibodies that can neutralize numerous HIV strains.
More clinical studies will be required before a vaccine capable of preventing HIV infection can be developed.
Multiple HIV strains are being targeted.
The coronavirus spike protein is well-known, and mRNA vaccines teach the immune system to create antibodies that target the spike protein and prevent the virus from infecting cells.
A spike-shaped virus protein called Env, or the envelope protein is also seen in HIV. The structure of this protein varies between viral strains, making it more difficult to target with antibodies.
In a Scripps Research YouTube video, William Schief, Ph.D., a professor, and immunologist, stated, “Antibodies against one virus — against one HIV spike — will not inhibit another HIV spike.”
He explained, “We need to elicit antibodies that bind to certain areas on the spike that don’t vary significantly.”
Scientists discovered broadly neutralizing antibodies that target this non-changing, or conserved, regions of the HIV envelope protein in the early 1990s. Since then, more antibodies have been discovered.
However, there are several processes involved in getting from vaccine to broadly neutralizing antibodies.
Schief and his colleagues at Scripps Research Institute and the International AIDS Vaccine Initiative created a candidate vaccine that stimulates the immune system to produce precursor cells, which are required to begin the process.
A phase 1 clinical trial published earlier this year found that 97 percent of people who got the vaccination had the appropriate immunological response.
This is the first of several “priming steps” that researchers believe will result in broadly neutralizing antibodies against HIV.
Schief claimed in the YouTube video that the immune cells created in response to the candidate vaccine “don’t know how to neutralize HIV yet,” and that he didn’t expect them to.
“However, we’ve studied them and now have a solid concept of how our second shot should be.”
Using an mRNA vaccine to fight HIV
Moderna has joined with the International AIDS Vaccine Initiative and Scripps to test an mRNA-based vaccine variant of this method.
The blueprint for creating a certain protein is contained in messenger RNA or mRNA. These instructions are delivered to the cells through MRNA vaccinations, which subsequently manufacture the protein.
The mRNA vaccine will carry the instructions for a protein that stimulates the immune system in the phase 1 study using Moderna’s technology, similar to the Scripps and International AIDS Vaccine Initiative trials.
This study will enroll 56 healthy persons who are HIV-free and will test two vaccine candidates.
Two groups will receive a combination of the two vaccine options, while the other two will receive either one or the other.
The vaccine will be tested to see if it produces the desired immunological response — immune precursor cells — and if there are any safety issues.
Because this is the first of numerous clinical trials, scientists will have to wait a while to see if this strategy helps prevent HIV infection.
Many people will be waiting to see if the mRNA technology works as well for HIV as it did for COVID-19.
“At the very least, I hope that the lessons acquired from the COVID-19 trials can be used to the development of a safe and effective HIV vaccine,” said Anthony J. Santella, Ph.D., a public health researcher at the University of New Haven.
HIV testing and treatment remain critical tools.
Although mRNA technology appears to promise, creating a safe and efficient vaccine to prevent HIV infection has proven to be extremely difficult over the past few decades.
A clinical trial of an HIV vaccine that uses the same technology as Johnson & Johnson’s COVID-19 adenovirus (Ad26) vaccine has delivered the latest blow.
Imbokodo was research that included over 2,600 women in southern Africa who were at high risk of HIV infection.
The vaccine’s efficacy was only 25%, significantly below the 50% aim, according to results presented this week.
In a news release, Dr. Larry Corey, a virologist at the Fred Hutchinson Cancer Research Center and the study’s lead investigator, said, “Despite the use of Ad26 technology, which is effective for COVID-19, the Imbokodo study illustrates that HIV is a virus that requires a higher degree of immune response to achieve effective protection.”
A second HIV vaccine experiment will continue, this time with a different vaccine regimen in a different group.
Even if a possible HIV vaccine candidate is identified soon, Carl Schmid, executive director of the HIV+Hepatitis Policy Institute, warns that it will take time to test it in clinical trials and roll it out to the rest of the world.
“In the interim, we can avoid further [HIV] transmission and infections by testing and treatment,” he added, adding that “people can now protect themselves using PrEPTrusted Source [pre-exposure prophylaxis].”
Around 37 million people worldwide are infected with HIV. According to UNAIDS, 1.5 million people got HIV in 2020.
Santella believes the COVID-19 pandemic has taught the HIV community more than only about mRNA vaccine technology.
“With COVID-19, we experienced directly what can be done when local, state, and federal authorities and politicians desire to prioritize something,” he said.
“I expect the HIV community to now using our COVID experience to put people in positions of power and privilege on notice and demand the same efforts to end the HIV epidemic as we did with COVID.”