A vaccine prevents or controls a specific infection by training the body's immune system to fight it. Over the years, scientists have made vaccines for various diseases including polio, influenza, and smallpox. Even though it has been decades since the discovery of the virus, a vaccine for HIV has yet to be found, because the development process takes a long time.
HIV drugs have vastly improved the quality of life for people living with HIV and AIDS, but they cannot yet cure the infection. Someone at high risk for HIV can can take medications to help prevent infection, but these medications must be taken every day. That is why researchers are working hard to create an HIV vaccine. A vaccine prevents or controls a specific infection by training the body's immune system to fight it.
Although it has been decades since the discovery of the virus, an HIV vaccine is still yet to be found. The research process requires a long time and a lot of funds. For example, the polio virus was first identified in 1908 but it took until 1955 for the first polio vaccine to be approved.
An HIV vaccine is even more difficult because:
- Many types of HIV exist, and new types keep forming
- HIV has clever ways of "outwitting" the immune system
- Scientists still do not completely understand what parts of the immune system work against HIV
Despite the complex challenges, many researchers are hopeful about the prospects of an HIV vaccine.
TWO KINDS OF VACCINES
There are 2 types of vaccines being developed:
- Preventive Vaccine
This vaccine can be given to someone who is negative for HIV because this vaccine does not contain live virus so it is safe to give without fear of contracting the HIV virus.
This type of vaccine trains and encourages the immune system to "recognize", make antibodies and fight off HIV before the virus causes infection and illness.
- Therapeutic Vaccine
Would help control infection and delay the progression of the disease. This vaccine works by ramping up the immune system to find and kill HIV-infected cells. And preventing or limiting HIV from making copies of itself. This vaccine is tested on someone who is already positive for HIV, but has a healthy immune system.
VACCINE TESTING AND CLINICAL TRIALS
First, HIV vaccines are tested in labs and animals. Then, a single HIV vaccine could take years of testing in humans before it would be OK for the public. A vaccine to prevent HIV typically goes through three phases of clinical trials to test its safety and effectiveness.
Each phase must go well in order to move on to the next one.
- Phase I lasts between 12 and 18 months. Small numbers of healthy, HIV-negative volunteers help researchers test the safety and figure out best doses
- Phase II can last up to 2 years. Hundreds of healthy, HIV-negative volunteers help researchers to refine dosing and test how well the immune system responds
- Phase III can last 3 to 4 years with thousands of healthy, HIV-negative volunteers.
mRNA VACCINE TRIALS FOR HIV
The International AIDS Vaccine Initiative (IAVI), a nonprofit group, and biotechnology company Moderna launched the phase I human clinical trial with an experimental HIV vaccine made using mRNA technology. It is the same kind that is used in COVID-19 vaccines.
Volunteers from the George Washington University School of Medicine and Health Sciences in Washington, DC, have received the first round of the experimental shots. This study involved 56 volunteers who were negative for HIV, aged 18 to 50 years. The volunteers were divided into four groups and given one or two doses of the trial vaccine. Several volunteers also received boosters.
Clinical trials were conducted to see if the mRNA vaccine (which is an HIV protein), can stimulate the immune system to produce B cells (a type of white blood cell). It is hoped that these B cells will later turn into Broadly neutralizing antibodies (bnAbs), antibodies that are able to neutralize most HIV-1 strains from various genetic and geographical backgrounds. The mechanism of action of bnAbs is to bind to gp120 and gp41 sites on the surface of HIV so that HIV cannot bind to immune cells.
Antibodies are proteins that immune cells make to block viruses and other infectious agents. In the case of HIV, people who are infected typically produce antibodies to the virus. But because the virus mutates and replicates rapidly, antibodies are largely ineffective at controlling the virus. After years of infection, though, some people produce highly potent antibodies called Broadly Neutralizing Antibodies (bnAbs) that, in laboratory tests, can neutralize a wide variety of HIV strains.
The identification of such antibodies has transformed the field of HIV prevention research for two reasons: it provides information to guide the design of vaccines that could elicit bnAbs for protection, and it has opened the door to a new prevention modality: the administration of HIV bnAbs to prevent infection.
Reference:
- How Vaccines Are Developed
- Majalah Farmasetika. (2020). Antibodi Monoklonal bnAbs Sebagai Pencegahan dan Pengobatan Infeksi HIV
- WebMD. (2022). Could a Vaccine Fight HIV?
