Why in News:

• Moderna, the Massachusetts-based American biotechnology company, has indicated that it may begin human trials for a vaccine for HIV (human immunodeficiency virus).

What is HIV?

• HIV (human immunodeficiency virus) is a virus that attacks the body’s immune system. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome).
• There is currently no effective cure. Once people get HIV, they have it for life.

How does the proposed vaccine work?

• Formally known as mRNA-1644, it is made in a way to stimulate the B cells of the immune system.
• B cells are a class of white blood cells that produce antibodies which can bind to invading bacteria and viruses.
• The larger purpose of stimulating the B cells is to generate what are called broadly neutralising antibodies (bnAbs), which are specialised blood proteins that attach to the surface proteins of HIV and disable them by accessing key but hard-to-reach regions on the virus.

The good and bad of m-RNA vaccine

• RNA-based immunogens are believed to be a promising alternative because they do not involve the use of a live virus, can be made relatively easily, can be quickly deployed and safely administered. 
• But, the challenge with m-RNA vaccines is that they are sensitive to temperature in storage, and is a challenge for developing countries. 

What is the present treatment for HIV?

• The treatment for HIV is called antiretroviral therapy (ART). ART involves taking a combination of HIV medicines (called an HIV treatment regimen) every day.
• ART is recommended for everyone who has HIV. People with HIV should start taking HIV medicines as soon as possible. ART can’t cure HIV, but HIV medicines help people with HIV live longer, healthier lives. ART also reduces the risk of HIV transmission.
• A main goal of HIV treatment is to reduce a person’s viral load to an undetectable level. An undetectable viral load means that the level of HIV in the blood is too low to be detected by a viral load test. People with HIV who maintain an undetectable viral load have effectively no risk of transmitting HIV to their HIV-negative partners through sex.

References: 

1. https://www.thehindu.com/sci-tech/health/explained-how-will-human-trials-for-new-hiv-vaccine-work/article36039000.ece
2. https://www.cdc.gov/hiv/basics/whatishiv.html
3. https://hivinfo.nih.gov/understanding-hiv/fact-sheets/hiv-treatment-basics