The Massachusetts-based biotechnology company, Moderna, is now in the news for beginning human trials for its novel mRNA-1644 vaccine aimed at battling the Human Immunodeficiency Virus (HIV). This attempt comes in the wake of the success of mRNA vaccines against Covid-19. As per the World Health Organization (WHO), it is estimated that around 37.7 million individuals were living with HIV in 2020.
Understanding the Differences: mRNA Vaccine vs Traditional Vaccines
First and foremost, it’s crucial to understand how vaccines work. Essentially, they train the body to recognize and respond to proteins produced by disease-causing organisms, such as viruses or bacteria. Traditional vaccines are generated from small or deactivated doses of the whole disease-causing organism, or the proteins that it produces. These are introduced into the body with the aim of provoking the immune system to mount a response.
Contrarily, mRNA vaccines trick the body into producing some of the viral proteins itself. They employ messenger RNA (mRNA), the molecule responsible for implementing DNA instructions. Inside a cell, mRNA acts as a template to build a protein.
How Will the mRNA Vaccine Work for HIV?
The HIV vaccine by Moderna is anticipated to work similarly to the Covid-19 vaccine. It ideally persuades the body’s cells to produce the spike protein of the HIV virus, triggering an immune response.
This process stimulates B cells to generate broadly neutralising antibodies (bnAbs). These sophisticated blood proteins attach to surface proteins of HIV and disable them by accessing critical but hard-to-reach regions on the virus. B-cells combat bacteria and viruses by creating Y-shaped proteins or antibodies, which can latch onto the surface of an invasive cell and mark it for destruction by other immune cells.
In recent years, there have been advances in identifying new bnAbs from HIV-infected individuals that target specific sites in the outer envelope of the HIV. Laboratory-based tests and animal studies have contributed to understanding how these sites can serve in creating immunogens.
An immunogen induces an immune response by an organism’s immune system, whereas an antigen binds to the product of that immune response. Essentially, every immunogen is an antigen, but not every antigen is an immunogen.
Potential Benefits and Challenges
Utilizing RNA-based immunogens presents an appealing alternative as it eschews the use of a live virus, is relatively easy to manufacture, can be quickly distributed, and administered safely.
However, challenges lie in their reach, temperature sensitivity, and the mutation of HIV. The distribution of essential vaccines like those by Moderna and Pfizer to regions most in need has been a significant hurdle. Notably, two-thirds of people living with HIV are in Africa, and to effectively contain the HIV pandemic, transmission rates in these areas must be drastically reduced. Furthermore, m-RNA vaccines’ sensitivity to temperature during storage presents another challenge for developing countries.
Additionally, HIV is a mutating virus with several variants, making it challenging to combat. It’s anticipated to be several years before the success of the mRNA approach can be definitively proven.
An Overview of HIV
HIV targets CD4, a type of white blood cell (T cells) crucial to our immune system. These cells move around the body identifying abnormalities and infections in cells. After entering the body, HIV multiplies and destroys CD4 cells, severely impairing the human immune system.
The virus, once in the body, cannot be eliminated. An individual infected with HIV sees a significant reduction in their CD4 count. In a healthy individual, the CD4 count ranges between 500-1600, but in an infected body, this can drop to as low as 200. A weakened immune system leaves an individual vulnerable to opportunistic infections and cancer, making recovery challenging even from minor injuries or illnesses. Thankfully, with proper treatment, severe forms of HIV can be prevented.
Current HIV-related Initiatives
Several initiatives have been launched to combat HIV, such as the HIV & AIDS Prevention and Control Act of 2017, Project Sunrise, 90-90-90, The Red Ribbon, and the Global Fund to Fight AIDS, Tuberculosis, and Malaria (GFATM).
Last Modified: February 13, 2024