Jan 062012
 
2012-01-06_230335

Despite the progress of the research, provided the first description of AIDS in June 1981, pronounce the word "cure" is foolhardy. In May 1983, isolating the agent responsible for this overall impairment of the immune system, subsequently named human immunodeficiency virus (HIV). Thirty years of research enabled us to reach a detailed mechanisms extremamento knowledge of replication of the virus and its spread in different compartments of the body, where it settles so latent in reservoirs.

The most notable results of this scientific progress are the combinations of antiretrovirals (ARV), which emerged in 1996 and has more than 85% reduction in the mortality of patients your action is, in addition to preventive therapy. Since 1994, the clinical experiment showed the effectiveness of ACTG076 azidotimina ("AZT") to prevent the transmission of HIV in pregnancy. Recent studies have confirmed the power of ARVs to reduce drastic the sexual transmission of the virus.

Are very important results. To prove that the ARVs allow not only save many lives, but also prevent new contaminations and curb the spread of the epidemic, require an acceleration of universal access to treatment. In Botswana, where coverage for 90% of antiretrovirals, "the number of new HIV infections is 30% to 50% lower than that which would, in the absence of universal access to treatment," indicates the last UNAIDS report (1).

However, many countries do not have the resources that would make it possible to tackle the high cost of treatments. Depend on international solidarity. Unfortunately, the global financial crisis casts heavy uncertainties about the future of such financing, because the donor countries do not respect their commitments. The lack of ARVs already is felt in many receiving countries. They become unable to treat new patients and risk up to interrupt ongoing treatments. The situation is even more disturbing because the interruption of therapy can lead to the emergence of resistant HIV strains, and pave the way for the emergence of a worldwide epidemic.

The fight against a pandemic such as HIV may not be weakened by political volatility. It is imperative to find innovative funding mechanisms and perennial, as the tribute on airline tickets that feeds the bottom of Unitaid. For years, various movements claim that taxing financial transactions for the benefit of health in developing countries. We must make every effort necessary for this proposal to be considered by the G-20 countries.

In parallel, we must redouble efforts to develop new therapeutic options. We must not forget that, although anti-retroviral drugs to patients living with HIV – which is already very-, the treatment of this infection is still heavy. The cocktail of drugs, which have side effects, need to be used over a lifetime, without flaws. But they do not completely eliminate the virus, whose persistence in the reservoirs of the body is associated with a chronic and widespread inflation of the immune system. Patients do not recover a life expectancy similar to that of the general population. They suffer from, among others, higher risks of cardiovascular, neurological diseases, cancer and premature aging of the organism.

Eradicate HIV infection will be for some time yet, a dream. Meanwhile, a set of templates allows you to think that we could, at one time, turn this dream into reality, developing short therapeutic strategies, allowing to reach a long-term remission, regardless of any type of treatment.

Recently, the case of Timothy Ray Brown, called the "Berlin patient", demonstrated the feasibility of such a strategy. This man in his forties, who lived with HIV, has developed a leukemia. Required to perform a bone marrow transplant to cure it, your doctor has selected a compatible donor, but that had, moreover, a peculiarity: a genetic mutation of the coreceptor CCR5-a molecule on the surface of CD4 T cells, the virus interacts, to penetrate them. We know a few years ago that some rare individuals – of Caucasian origin – have this mutation, called Delta 32, which makes them resistant to HIV infection.

In February 2007, at the time of the marrow transplantation, antiretroviral treatment was stopped. Since then-about five years – do not detect any trace of the virus in the patient, even when employees the most sensitive methods and when it scours all the compartments in which HIV establishes reservoirs (intestines and central nervous system). However, your body continues to produce antibodies against the virus, indicating that the infection may not have totally disappeared. From a scientific point of view, it is difficult to say if, at the origin of this "cure", is only the Delta 32 mutation. Imunodepresssivos treatments that accompany such a complex surgery may have played a role. Although it is impossible to imagine the large-scale development of a method extremely risky and costly, the unique case of the "Berlin patient" offers a scientific reason for gene therapy approaches that have targeted, among others, the CCR5 receptor.

The "control" patients of HIV represent the ideal model of long-term healing. This is rare individuals (less than 0.3% of people infected with HIV), HIV-positive for more than ten years, remain without any treatment a undetectable viral load, and do not present any sign of AIDS progression. It is observed in these patients, notably, a reservoir of HIV level more fragile than in the other. We now know that the maintenance of this natural and extremely powerful control – infection is assured by two different mechanisms. The first concerns the immune cells called cytotoxic (which eliminate the infected cells). The second is connected to an intrinsic resistance of immune cells. The understanding of these mechanisms can help us develop new therapeutic strategies, so that one day all people living with HIV pass control your infection even stopping treatment majority today.

In addition, there are in France a single study, called "Visconti", which brings together eighteen patients. Diagnosed and treated between two and three months after infection, they stopped, according to his doctors, the treatment after a few years. Since then, control the infection. These observations confirm the enormous benefit of a ultra-precoce treatment. Analysis of immunologic characteristics that allow these patients may provide therapies information dispensing extremely precious.

One last important model is the monkeys of Africa, natural hosts of Simian immunodeficiency virus (SIV), which gave rise to HIV. Unlike HIV-infected human, monkeys do not develop AIDS. If your immune system reacts to the infection, this response is quickly suppressed. Results: among them, the virus multiplies freely, without notice the terrible chronic inflammatory reaction that affects the human being.

What mechanisms is necessary to induce, to trigger a protection against HIV-AIDS? This is still a mystery. Most likely, a combination of therapeutic and vaccine approaches will be required. That is why, under the aegis of the International AIDS Society (International AIDS Society (IAS)), a working group composed of scientists from all over the world deals with a global strategy, able to define the priorities that we must pursue, hoping one day to live in a world without HIV/AIDS. The searches are not only useful to fight against AIDS.

HIV can be, well, a tool that helps to better understand the precise mechanisms that control our immune response. We have much to learn from our colleagues working with cancer and other chronic diseases also linked to inflammatory abnormalities.

In this period of crisis, there are two possible options: solidarity and cooperation, established at the beginning of the epidemic. Or each-one-for-itself, a choice that would produce only losers

By Françoise Barré-Sinoussi, in Le Monde Diplomatique | Translation: Antonio Martins

AIDS: among the possible healing and a new global outbreak

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