Though the first American cases of HIV occurred in 1981, little progress has been made toward developing a vaccine for the condition. There are several reasons for this. HIV’s variable nature allows the virus to impair immune cells early into the infection. This variability also means that it can establish latent infection while integrating itself into the host’s genome. Unfortunately, this makes it almost impossible for any individual to develop a 100 percent effective immune response, making vaccine production complex.
Fortunately, the introduction of messenger RNA (mRNA) vaccines to combat COVID-19 may hold the key to HIV vaccine development.
To understand how it’s important to note the differences between mRNA vaccines and traditional vaccines.
Traditional vaccines usually trigger an immune response by placing a weakened or inactive germ into the host’s body. This approach enables the body to develop a blueprint for combating the germ, allowing it to prevent the spread of the virus associated with the germ if the host comes into contact with it.
Sadly, this approach does not work for variable viruses, such as COVID-19 and HIV.
mRNA vaccines differ from traditional vaccines because they don’t require the use of a germ. Instead, scientists create proteins in laboratories that are injected into the host. The protein causes an immune response, which allows the body to learn how to break the protein down and get rid of it. Crucially, the proteins introduced are vital to the function of the virus the vaccine protects against. In COVID-19’s case, the protein in mRNA vaccines is the same one that all human COVID viruses use to enter and attach themselves to host cells. By breaking that protein down, your body prevents the virus from entering your cells.
This innovative approach to vaccine technology has opened the door for new ideas for combating HIV. In fact, some researchers are already experimenting with mRNA vaccines for the condition.
In 2021, a team of researchers at the National Institute of Allergy and Infectious Diseases (NIAID) developed an mRNA HIV vaccine for use in animals. The vaccine contained instructions on how to create Env and Gag, which are two critical HIV proteins. Though they lack the genetic code required to cause HIV infection, these proteins provoke an immune response similar to the one HIV produces.
The researchers began by injecting their new vaccine into mice.
After two injections, the mice developed antibodies that they’d produce if they had a full HIV infection.
Buoyed by these results, the researchers turned their focus to seven rhesus macaques. They injected a primer vaccine into the macaques, followed by several booster shots. After 58 weeks, researchers saw that all of the vaccinated macaques developed a measurable amount of HIV antibodies. Interestingly, the vaccine also prompted other immune responses, such as the creation of more helper T cells.
Following the inoculations, researchers exposed the macaques to simian-human HIV (SHIV). After 13 weeks, two of the seven monkeys had not contracted SHIV. The other five experienced an infection delay that took place over eight weeks. For reference, the typical infection time for an unvaccinated animal is three weeks. Ultimately, the mRNA vaccine injected into the macaques led to a 79% lower risk of SHIV infection per exposure.
Of course, these experiments have yet to lead to a vaccine that may help humans. However, the early results presented are promising enough to demonstrate that an mRNA vaccine could help solve the HIV puzzle. Further research and experimentation may help researchers isolate more proteins that create a stronger immune response. The NIAID team also plans to trial the vaccine in healthy adult volunteers after further testing.
There is no guarantee that mRNA vaccines will create 100 percent immunity against HIV. However, the constant advancements in this field mean these types of vaccines may be able to succeed where traditional vaccines have failed.
