CCR5 Delta 32

Prelims level : “Science and technology-Bio-technology.” Mains level : GS-3 “Science and technology, effects and application development in everyday life.”
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  • For just the second time since the global epidemic began, a patient appears to have been cured of infection with HIV, the virus that causes AIDS.

About the News:

  • This is the second Patient to be cured of HIV AIDS
  • Both milestones resulted from bone-marrow transplants given to infected patients. But the transplants were intended to treat cancer in the patients, not HIV.
  • The transplants were from a donor with a mutation in a protein called CCR5, which rests on the surface of certain immune cells. HIV uses the protein to enter those cells but cannot latch on to the mutated version.
  • CCR5 is the protein that He Jiankui, a scientist in China, claimed to have modified with gene editing in at least two children, in an attempt to make them resistant to HIV — an experiment that set off international condemnation.

About CCR5-Delta 32 Mutation:

  • The remarkable research breakthrough that appears to have cured the anonymous “London Patient” of HIV is based on a stem cell transplant involving CCR5-delta 32 homozygous donor cells.
  • This is the same treatment that cured Timothy Ray Brown, known as the “Berlin Patient” when he received two stem cell transplants in 2007 and 2008.
  • HIV uses the CCR5 protein to enter immune cells, but it can’t latch on to cells that carry the delta 32 mutation. IciStem, a consortium of European scientists studying stem cell transplants to treat HIV infection, has a database of 22,000 donors with this HIV-resistant mutation. About 1% of people of Northern European descent, mainly Swedes, are born with a mutation known as CCR5-delta 32, which “locks ‘the door’ which prevents HIV from entering into the cell. This is only going to work if someone has a virus that really only uses CCR5 for entry. Patient would still be vulnerable to a form of HIV called X4, which employs a different protein, CXCR4, to enter cells.

Brown’s Case:

  • Dr Hütter put Brown through an allogeneic stem cell transplant, which involved replacing his immune system with donor hematopoietic stem cells (usually found in bone marrow) so that his immune system could be regenerated, with no malignant cells. Importantly however, the donor he chose carried what is called a CCR5-delta 32 mutation.
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