Discovery of a mechanism that enhances the natural immunity against HIV

A team of scientists from the Massachusetts Institute of Technology (MIT), the Institute Ragon Massachusetts General Hospital (MGH) and Harvard University have discovered that a particular gene found in people naturally immune to HIV-HLA-B57 causes the body to make a greater number of more lethal cells of the immune system attacking the virus and defend the body from infection.

The finding, published in the online edition of “Nature” and directed by Professors Arup Chakraborty (MIT) and Bruce Walker (MGH), could help researchers develop vaccines that provoke the same response to the HIV virus that that individuals with this particular gene generated by themselves. When people are HIV infected, it is normal to be only a matter of time, unless prevented by drugs, your body develops AIDS. However, there is a small group of people exposed to this virus, very slowly developing disease and, in some cases does not even develop it. The researchers demonstrated in the late 90s that a high percentage of people who showed naturally immune to HIV, representing one in every 200 individuals, were carriers of a gene called HLA B57.

The new research has found that the HLA B57 gene causes the body to build more T-cells white blood cells that help defend the body against infections, more powerful and lethal. Patients with this gene have an increased number of T cells that adhere more strongly to most proteins of HIV than people who lack this gene. This makes the T cells are better able to recognize cells expressing HIV proteins, including mutated versions that arise during infection. This effect helps these individuals have a better control of HIV infection and other viruses that develop quickly, “but also makes these patients more susceptible to autoimmune diseases in which T cells attack body’s own cells.

Most T cells are lethal only from a genetic point of view and recognize different pieces of foreign proteins, called epitopes, attached to the surface of cells that have been infected by viruses or bacteria. After a killer T cell is hooked to one of these proteins, is activated and begins to sweep the other body cells that express the same type of protein, to exterminate them. In addition, cloned themselves to create an army of T cells whose purpose is to attack the invader.

This work has shown that individuals with HLA B57 gene produce a greater number of T cells that are cross reactive, which means they can attack more than one epitope associated with HIV, including mutations that appear to escape activated T cells. Their findings could help researchers design a vaccine that helps to generate T cells able to have cross-reactions in people who lack a gene called HLA B57.

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