Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging the immune system, mainly CD4 cells, HIV interferes with the body's ability to fight infection and disease.
HIV is a sexually transmitted infection (STI). It can also be spread by contact with infected blood or from mother to child during pregnancy, childbirth or breast-feeding. Without medication, it may take years before HIV weakens the immune system to the point that one has AIDS. Although HIV is known to have no cure, a few people have undergone successful treatment and have been cured of this disease.
Timothy Ray Brown, an American was the first person cured of HIV. He was called “The Berlin patient” at the ‘Conference on Retroviruses and Opportunistic Infections’ in 2008, where his cure was first announced. Mr. Brown was diagnosed with HIV in 1995 while studying in Berlin. In about a decade, he was diagnosed with acute myeloid leukemia, a cancer of the blood cells of the myeloid tissue in the bone marrow. In 2007, he had a bone marrow transplant known as the hematopoietic stem cell transplantation to treat the cancer, it was found that the bone marrow of the donor was naturally resistant to HIV due to a genetic mutation.
This transplant was repeated after a relapse of the cancer. The researchers could not detect HIV in his blood and biopsies despite discontinuing antiretroviral therapy. However, he suffered from complications due to the transplant, which led to a decision that the transplant should not be performed on other affected individuals, although sufficient donors could be found.
In 2018, Mr. Brown died at the age of 54 due to the recurrence of leukemia but he was HIV free.
Adam Castillejo, the second person cured of HIV in 2019, is called “The London Patient”, he was first diagnosed with HIV in 2003. He also underwent a bone marrow transplant to treat lymphoma, a cancer of the lymphatic system. He is still free of the virus, more than 37 months after stopping antiretroviral therapy.
Why are some people resistant to infection?
A genetic mutation known as C-C chemokine (chemotactic cytokine) receptor type 5 (CCR5-delta 32) on chromosome 3 is responsible for the two types of HIV resistance that exist. CCR5-delta 32 is a protein on the surface of white blood cells that acts as a receptor for chemokines.
Mutated CCR5 hampers HIV's ability to infiltrate immune cells. CCR5 coreceptor is like a door that allows HIV entrance into the cell. The CCR5- delta 32 mutation in a sense locks "the door" which prevents HIV from entering into the cell. 1% of people descended from Northern Europeans, particularly Swedes, are immune to HIV infection. They are homozygous carriers of the mutated gene. 10 -15% of people with European heritage have inherited one copy of the gene. Just one copy of the mutation does not prevent against infection. It does however reduce carrier's chances of infection and delays the progress of AIDS. Since the CCR5-delta 32 is tied primarily to the Eurasia region, the mutation has not been found in Africans, East Asians, or Amerindians.
This principle is used currently to treat patients infected with HIV. The CCR5 mutation’s virus-blocking power is simulated by a drug called Selzentry that prevents HIV from using the CCR5 receptor by binding to the receptor itself. It keeps the virus at bay as long as the drug is taken continually.
HIV was once disease that was thought to be fatal and have no cure, but this view has now changed. Timothy Ray Brown and Adam Castillejo are thus ambassadors of hope, and have paved the path for new discoveries and cures in this field.
Anna Riya
3rd Year CZM
For Further Reading
⦁ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1539443/
⦁ https://www.who.int/news-room/fact-sheets/detail/hiv-aids
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