HIV Resistant Genetic Mutation

Context

A 53-year-old German man recently became the third person to successfully treat HIV using bone marrow from donors with a particular genetic mutation that makes people resistant to the virus.

Probable Question

Describe the effects of a bone marrow transplant containing a particular mutation that makes people HIV-resistant. (150 words, 10 marks)

About HIV-Resistant Genetic Mutation

• HIV (Human Immunodeficiency Virus) mainly attacks the CD4 immune cells in the human body, thereby reducing a person’s ability to fight off secondary infections. 
• The doctors to treat HIV select a donor carrying two copies of a CCR5-delta 32 genetic mutation, a mutation that is known to make the carriers almost immune to HIV.
• In 2022, a dual stem cell therapy that combined the use of adult stem cells and neonatal stem cells from the neonate's umbilical cord was implemented. It is because this requires less restrictive HLA matching.
• The CCR5-delta 32 mutation, which is naturally present primarily in Europeans, may make it easier for people of different races to receive transplants, making HIV-resistant genetic mutation important.

About CCR5 Mutation

• The HIV virus enters the body through the CCR5 receptors on the surface of CD4 immune cells. 
• The CCR5-delta 32 mutation blocks the surface formation of these HIV virus-used receptors, thus closing the doorway.
• Only 1% of the world's population carries the CCR5-delta 32 mutation in two copies, meaning they acquired it from both parents.
• While 20% of people, mostly those with European ancestry, carry one copy of the mutation. People who have the mutation are therefore essentially immune to the infection, though some cases have been documented. 

Drawbacks of HIV Transplant Treatment

• Unavailability of Compatible donors: Due to the current prevalence of HIV among 38.4 million people and the rarity of the mutation, finding compatible donors for the transplant would be extremely challenging.
• Shortage of Donors: Since the mutation mostly affects Europeans, fewer people can donate, especially those from nations with high HIV prevalence.
• Risk of rejection of donated bone marrow: Even if bone marrow transplants are available to all HIV-positive people in the future. Still the procedure involves high risks, particularly the risk of the recipient rejecting the donated bone marrow.
• Risk of Mutation: It's also possible that in these people, the virus will mutate and find new ways to enter the cells.

Current treatments for HIV

• In the Acquired Immunodeficiency Syndrome (AIDS) stage, where multiple opportunistic infections can be fatal, a person's immune system is destroyed by the virus if they are not treated.
• Despite the fact that there are currently no treatments for the infection, antiretroviral therapy can be used to control the illness. 
• These drugs prevent the virus from replicating within the body, allowing the number of CD4 immune cells to increase once more. 
• Although the government's program used to only provide the drugs to people with low CD4 counts, the possibility of an individual spreading the infection is low when viral levels are low. The government now supports anyone who has been diagnosed with HIV.
• As long as the virus remains dormant in the body's reservoirs, the medications must be taken continuously. The virus can once more begin replicating and spreading if the medications are stopped. 
• There are also Pre-exposure prophylaxis (or PrEP) medicines that can be taken by people at high risk of contracting the infection. PrEP reduces the risk of getting HIV from sex by about 99%.

News Source: The Indian Express

https://indianexpress.com/article/explained/explained-health/hiv-cure-8462781/

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