We are doing studies of preventive vaccines and broadly neutralizing antibodies (bnAbs) against HIV. There are many common vaccines that you have probably gotten: the polio vaccine, the Measles-Mumps-Rubella (MMR) shot, and the ﬂu shot just to name a few. We hope to ﬁnd a shot against HIV to add to the list!
Unlike some of these vaccines, HIV vaccines contains no live or killed HIV, so there’s no way that an HIV vaccine can cause infection. Broadly neutralizing antibodies (bnAbs) are the newest advance in HIV prevention research. When studied in lab tests, they seem to be able to block HIV infection from the many different strains of HIV found around the world. Many of our bnAb studies are done in partnership with the HIV Prevention Trials Network (HPTN).
Vaccines are used to train our bodies’ immune system to fight off bacteria and viruses that can cause disease. That response especially depends on two main parts of the immune system: antibodies and T-cells. Antibodies prevent infections, and T-cells help to clear out the infected cells if an infection does happen. A vaccine can teach antibodies and T-cells what HIV looks like, so that our bodies are prepared to fight back faster if we are ever exposed to HIV.
You can think of making a vaccine like making a sandwich. What kind of a sandwich is the best? It could be turkey with cheese on whole wheat bread, or egg salad on a croissant, or 50 other options! In the same way, scientists are looking at many different options for what would work best as an HIV vaccine. This involves using genes and proteins that are copied from HIV and manufactured in a lab to use in the vaccine (like the sandwich filling). No real HIV, living or dead, is ever used in our vaccines, so it is impossible for the vaccines to cause HIV infection. We also have to think about what will carry those genes and proteins (the “bread” in our sandwich). We test many different kinds of carriers too, including using other viruses and DNA, for example. And just like a sandwich, sometimes vaccines need a little boost for more flavor, so we add adjuvants for a stronger immune response. You can think of them like spicy mustard or hot sauce! When you contact us, we can tell you more about the specific vaccines and adjuvants being used in any particular study.
Most antibodies that our bodies make are specific to one particular bacteria or virus. HIV is challenging because it has many different strains that are found in different parts of the world, so building a global vaccine is tough. But bnAbs block many different HIV strains found around the world, including in more than 90% of the global samples tested. Many new bnAbs have been discovered in the past few years, and studies are looking at them individually and in combinations. Antibodies work to block infection, and it is impossible for them to cause an HIV infection.
In traditional research, people get a vaccine and scientists wait to see if their bodies will respond by making antibodies against HIV. In bnAb studies, we skip that step and give people the antibodies directly. We do this using intravenous infusions, commonly known as “getting an IV,” or in some cases, with traditional shots in a muscle or under the skin. Another difference is that antibodies produced naturally by your body in response to a vaccine can last for a long time, but these laboratory-made bnAbs usually only last for a few months, so people need to get them on a regular schedule.
Pre-exposure prophylaxis means using medicines to prevent HIV infection. Truvada® is a pill approved for PrEP that is highly effective in preventing HIV when taken every day. It is not a vaccine, as it doesn’t mimic HIV or train your immune system to fight off infection. It is a pill that is also used to treat HIV. PrEP is a powerful prevention tool, but the only way we have eliminated any infectious disease is through a vaccine (like smallpox), and most scientists agree that we need a vaccine to fully control and eventually end the HIV epidemic.
Additionally, one prevention strategy, like PrEP, may not be suitable for all people. Having other options such as bnABs allows each person flexibility in managing their own HIV prevention choices.