| Who would have thought 10 years ago that there | | | | The DNA itself contains two strands of nucleotides |
| would be a cure for AIDS? Well, according to the | | | | base pairs that are twisted in a spiral shape like a |
| Journal Watch: HIV/AIDS Clinical Care, February 13, | | | | rope. The only difference is that there are only two |
| 2009, a 40-year-old HIV positive male German patient | | | | strands within the DNA helix while there are several |
| with Leukemia underwent bone marrow stem cell | | | | within the rope's helix. |
| transplantation, which completely eradicated the virus | | | | It is therefore a segment of this helix that is termed, |
| from his body, 2 years later. Removing HIV was not | | | | the gene. It is just like cutting a small segment from |
| the main reason why the patient underwent the risky | | | | a rope and examining the characteristics of that |
| procedure, doctors at the Berlin Charité Hospital | | | | segment from the rope. In our case, we will be |
| said. | | | | examining the piece of the DNA that codes for the |
| The principal reason was to treat the patient for | | | | CCR5 receptor, which is also a protein. We will find |
| leukemia, a disease characterized by an uncontrollable | | | | that in heterozygous individuals, only one section |
| increase or proliferation of malformed leukocytes and | | | | from one strand of the DNA codes for the defective |
| their precursors in the bone marrow and peripheral | | | | CCR5 receptor, while the opposite section on the |
| blood, caused by malignancy of the blood forming | | | | other strand of the DNA does not code for a |
| organs, National Institute of Health. Therefore, it was | | | | defective version but codes for the normal CCR5 |
| very unexpected to witnessed the complete | | | | receptor, which facilitates easy HIV infection. |
| absence of any HIV RNA traces, according to the | | | | People who are homozygous in relationship to the |
| doctors. | | | | defective genetic segment (32-bp deletion) on the |
| The process of transplanting healthy bone marrows | | | | DNA are therefore totally immune to the CCR5 mode |
| into people with HIV, have been done many times | | | | of HIV infection. And if those people were ever |
| before without any success of removing the virus | | | | going to get HIV, they will have to be infected with |
| from the body. So, one can understand why these | | | | a HIV variant that strictly invades the CXCR4 |
| doctors were not necessarily trying to use the | | | | receptor instead of the CCR5 receptor. |
| procedure to cure the patient of AIDS, but instead, | | | | On the other hand, individuals who have normal |
| were trying to cure him of his leukemia problem. | | | | proportions of CCR5 receptors on their CD4 T-Cells |
| Sometimes this is how a cure is achieved—by | | | | with no heterozygosity or homozygosity are 100% |
| sheer accident. Well, mankind has one on its hands as | | | | more susceptible to HIV infection. In fact, there are |
| we speak. One might be wondering what is so | | | | tests that can be done to determine whether or not |
| different about this bone marrow transplant and | | | | a person is heterozygous or homozygous for the |
| others done before it. The key ingredient is a | | | | defective CCR5 gene. |
| defective version of the white blood cell protein | | | | The HIV positive patient who was cured by the |
| chemokine receptor "CCR5." This protein receptor | | | | stem cell transplant was given a stem cell that was |
| and CXCR4 are both present on CD4 T-Cells and a | | | | taken from a person who was homozygous for the |
| few other immune system cells. | | | | CCR5 deletion on his/her gene. Deletion means that |
| The HIV virus generally enters the white blood cell | | | | the normal base pairings of the DNA segments |
| via the CCR5 receptor or the CXCR4 receptor. | | | | (genes) was changed into something else that does |
| However, if the CCR5 or CXCR4 receptors are | | | | not code for anything. It is not all segments on a |
| defective, the virus cannot access the T-Cells to | | | | DNA that codes for something useful. Therefore, this |
| infect them. HIV infections via the CXCR4 receptors | | | | is why the CCR5 receptor does not work and is |
| are rare, but they do occur by variant strains of the | | | | therefore defective. |
| virus, The Lancet, May 22nd 2002. | | | | Sometimes certain portions of the DNA are stop |
| Our discussion will therefore focus on the CCR5 | | | | codes, blanks or codes that do not provide |
| receptor. A very large percent of people have normal | | | | instructions to make any proteins. A perfect example |
| amounts of CCR5 receptors on their CD4 T-Cells. A | | | | of this is trying to build a car without a blueprint or a |
| few of us have limited or partial amounts while some | | | | schematic. It does not matter how much material is |
| of us have none at all. Well, in this instance, it pays to | | | | available. If there is no instruction of how to build |
| have none. People who have limited amounts of the | | | | cars, there will be no cars built. Our example is the |
| CCR5 receptor are heterozygous for the gene that | | | | same way. The DNA and segments (gene) of the |
| codes for it. | | | | DNA are blueprints that cells use to build different |
| A gene is a small segment of a double helical DNA. | | | | proteins for the body. |