Devangshu Datta: Towards an HIV cure

Devangshu Datta: Towards an HIV cure Advances in genetic engineering techniques may finally help us win the battle against this global scourge Devangshu Datta / New Delhi May 04, 2012, 00:53 IST

Since AIDS, or acquired immune deficiency syndrome, was identified in 1981, there has been only one medically-certified cure. That occurred under unusual circumstances and it gave researchers an important clue about new ways to attack the disease. Recent advances in genetic engineering techniques have aided in this process. Some studies offer new hope of a cure for the 35 million estimated to be infected worldwide.

No disease inspires as much superstitious dread. So far, AIDS is estimated to have killed over 30 million people and it infects millions every year. It is especially prevalent in Sub-Saharan Africa.

HIV is transmitted through the exchange of body fluids. Common causes of infection (not necessarily in order) include unprotected sex, blood transfusions, sharing needles and so on. The associations with promiscuity and drug addiction make it hard to implement policies to stop HIV-spread. What works best is a combination of sex education and drug awareness programmes, coupled with easy availability of condoms and disposable needles. But in conservative societies like India, people object to sex education. Some religions also discourage the use of condoms.

Someone infected with HIV (HIV-positive) may survive years, without symptoms. The virus attacks a class of white blood cells called CD4 T-cells. It inserts itself into the cell and replicates. T-cells are part of the natural immune system. Once AIDS develops owing to HIV taking over T-cells, the immune system shuts down. Most AIDS patients die of cancer, pneumonia, or some other infection.

The new approaches involve inserting immune genes into HIV-positive patients, through genetic engineering of stem cells. Every researcher is cautious about claims of cures. The characteristic long symptom-less periods and HIVs ability to hide can be cruelly deceptive. HIV-positive people are also vulnerable to quacks. Many charlatans, including a cross-dresser who teaches yoga on Indian television, have claimed at various times to have found AIDS cures.

Some people have natural genetic immunity for various reasons. Advances in understanding of genomes have helped identify some of the causes of immunity. Researchers have known for a while that a mutated gene called CCR5 Delta 32 offers natural immunity to HIV.

The mutation is rare and found only in a few northern Europeans. The normal CCR5 gene, which most people possess, is the receptor HIV uses to enter T-cells. HIV cannot use the Delta-32 mutated gene and, hence, cannot replicate in a host who has two copies of the CCR5 Delta 32 gene (one inherited from each parent). Even one copy of Delta 32 seems to offer some protection. Only about one per cent of northern Europeans possess both copies.

In 2007, Timothy Ray Brown, an American resident in Berlin, was HIV-positive and also under treatment for leukaemia. Leukaemia causes an abnormal increase in white blood cells and a drop in red cells. Blood cells are produced by bone marrow. One drastic treatment is a bone marrow stem cell transplant from a healthy person. This helps regenerate healthy blood with a good haemoglobin ratio, and a new immune system. Its dangerous since the patients entire immune system must be destroyed prior to the transplant.

Browns doctors at the Charite University Medicine Berlin, Kristina Allers and Gero Hutter, found a compatible donor who belonged to that rare one per cent with the Delta-32 mutation. Five years later, after the transplant procedures, the Berlin Patient, as Brown is called in medical journals, is still HIV-free and doctors concur that this is a functional cure.

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Devangshu Datta: Towards an HIV cure