23 February 2023

Third patient is cured of HIV: How did this happen and what are its implications?

GS-3:Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology and issues relating to intellectual property rights.

The Dusseldorf patient, a male from Germany aged 53, has joined the ranks of at least three individuals who have been declared “cured of HIV”. Despite discontinuing medication, the virus has remained undetectable in his body for a period of four years. The successful outcome was achieved through a bone-marrow transplant procedure involving donors with a genetic mutation that is known to provide resistance against HIV.

What is HIV?

• HIV (Human Immunodeficiency Virus)is a virus that attacks cells that help the body fight infection, making a person more susceptible to other infections and diseases.
• It spreads through contact with certain bodily fluids, such as blood, semen, vaginal secretions, and breast milk.
• Unprotected sex and sharing injection drug equipment are the most common ways of HIV transmission.

Discovering the HIV-Free: Meet the People Who Have Overcome HIV 

• Timothy Ray Brown, also known as the Berlin patient, became the first person to overcome HIV after undergoing two stem cell transplants in 2007 and 2008.

• The Berlin patient's doctors selected a donor with a CCR5-delta 32 genetic mutation, which is almost immune to HIV.

• Adam Castillejo, also known as the London patient, replicated the treatment and has remained HIV-free since 2019.
• The Dusseldorf patient, who underwent a transplant for blood cancer, has remained HIV-free four years after stopping antiretroviral medication.
• Two other cases, 'The City of Hope patient' and 'New York patient,' were reported in 2022.

• The New York patient received a dual stem cell therapy, which uses stem cells from both an umbilical cord and an adult, and requires less restrictive HLA matching.

• This new approach may help people from different races get a transplant with the CCR5-delta 32 mutation, which is mostly found in Europeans.

Understanding the CCR5 Mutation: A Potential Key to Fighting HIV

• The HIV virus primarily targets CD4 immune cells, which weakens the body's ability to combat secondary infections.

CCR5-delta 32

• CCR5-delta 32 is a rare genetic mutation that prevents the formation of CCR5 receptors on the surface of CD4 immune cells, which act as a doorway for the HIV virus. 
• This means that those who carry the mutation are almost immune to the infection, as the virus cannot enter the CD4 cells.
• Thus, the CCR5-delta 32 mutation removes the doorway that the HIV virus uses to enter the CD4 cells, effectively preventing the virus from replicating and spreading throughout the body.

Who carries the Mutation? 

• Only 1% of the world's populationhas two copies of the CCR5-delta 32 mutation, inherited from both parents, while 20% carry one copy of the mutation, mainly those of European descent.

How is the mutation being used to fight HIV? 

• Researchers have been exploring the use of gene-editing techniques to introduce the CCR5-delta 32 mutation into HIV-positive patients, with the hope of providing them with a cure for the disease. 
• The technique of bone marrow transplants from donors also succeed with the mutation in curing HIV-positive patients.

Limitations of using the mutation to fight HIV

• Though, people with the CCR5-delta 32 mutation are highly resistant to HIV infection, although some rare cases have been reported.
• Additionally, gene-editing techniques to introduce the mutation are still in the experimental stage and are not widely available.

Can Transplants Be the Answer to the HIV Crisis?

• The CCR5-delta 32 mutation is rare, occurring in very few people.
• With 38.4 million people living with HIV across the world, finding a matching donor is difficult.
• The mutation occurs mainly among Caucasians, shrinking the donor pool further.
• Even if donors were available, bone marrow transplants cannot be rolled out for all those with HIV due to the risks associated with the procedure, which include the person rejecting the donated marrow and the virus mutating to enter the cells through other mechanisms in such persons.

A cautionary Tale

• In 2018, Chinese scientist He Jiankuiedited the genomes of twins to remove the CCR5 gene, in an attempt to make them immune to HIV. (Their father was living with HIV)
• He faced immediate backlash from the scientific community and legal action for violating guidelines for genetic editing, as editing germ-line DNA can have long-term consequences. 
• Additionally, antiretroviral therapy could have prevented mother-to-child transmission of HIV.

Latest HIV Treatments: 

• HIV is a lifelong condition as there is no known cure for it.

• In the US, most people with HIV do not progress to AIDS because of the availability of HIV medicine.
• The drugs have to be taken for life as the virus persists in the body's reservoirs.
• Stopping the drugs can cause the virus to replicate and spread again.
• Low viral levels decrease the chances of transmitting the infection.
• HIV medicine can still help people at the AIDS stage of HIV infection and even save lives, but starting HIV medicine soon after contracting HIV is more beneficial. Therefore, Regular HIV testing is crucial to detect the infection at an early stage and start treatment early for better outcomes.

• In addition, effective treatment with AntiRetroviral Therapy (ART) can reduce the amount of virus in the blood and maintain an undetectable viral load.

• The therapy suppresses the replication of the virus and increases CD4 immune cell count.
• Earlier, the drugs were given only to those with low CD4 count but now anyone diagnosed with HIV is eligible for treatment.

• People with HIV who take ART as prescribed and maintain an undetectable viral load can live long and healthy lives and will not transmit HIV to their HIV-negative partners through sex.
• Effective methods such as pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) can effectively (99%) prevent getting HIV through sex or drug use.
• HIV, if left untreated, can lead to AIDS (Acquired Immunodeficiency Syndrome).

What is AIDS?

• AIDS is the advanced stage of HIV infection, where the immune system is severely damaged.
• A person with HIV is considered to have AIDS if their CD4 cell count falls below 200 cells/mm³ or if they develop one or more opportunistic infections.
• Without HIV medicine, people with AIDS typically survive for about 3 years. With a dangerous opportunistic illness, life expectancy falls to about 1 year.

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