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The fight against HIV / AIDS

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  • #46

    WASHINGTON, December 17, 2008 (Reuters) - Three studies published on Wednesday add to evidence that circumcision can protect men from the deadly AIDS virus and the sexually transmitted virus that causes cervical cancer.

    The reports in the Journal of Infectious Diseases are likely to add to the debate over whether men - and newborn boys - should be circumcised to protect their health and perhaps the health of their future sexual partners.

    Dr. Bertran Auvert of the University of Versailles in France and colleagues in South Africa tested more than 1,200 men visiting a clinic in South Africa,

    They found under 15 percent of the circumcised men and 22 percent of the uncircumcised men were infected with the human papilloma virus, or HPV, which is the main cause of cervical cancer and genital warts.

    "This finding explains why women with circumcised partners are at a lower risk of cervical cancer than other women," they wrote in their report.

    A second paper looking at U.S. men had less clear-cut results, but Carrie Nielson of Oregon Health & Science University and colleagues said they found some indication that circumcision might protect men.

    The circumcised men were about half as likely to have HPV as uncircumcised men, after adjustment for other differences between the two groups.

    In the third report, Lee Warner of the U.S. Centers for Disease Control and Prevention and colleagues tested African-American men in Baltimore and found 10 percent of those at high risk of infection with HIV who were circumcised had the virus, compared to 22 percent of those who were not.

    "Circumcision was associated with substantially reduced HIV risk in patients with known HIV exposure, suggesting that results of other studies demonstrating reduced HIV risk for circumcision among heterosexual men likely can be generalized to the U.S. context," they wrote.

    Studies supporting circumcision to reduce HIV transmission had all been done in Africa and U.S. studies were less clear.

    Dr. Ronald Gray of Johns Hopkins University in Baltimore and colleagues said they found the reports encouraging.

    "In the United States, circumcision is less common among African American and Hispanic men, who are also the subgroups most at risk of HIV," they wrote in a commentary.

    "Thus, circumcision may afford an additional means of protection from HIV in these at-risk minorities."

    But they noted that the American Academy of Pediatrics does not recommend routine circumcision for newborns.

    "As a consequence of this AAP decision, Medicaid does not cover circumcision costs, and this is particularly disadvantageous for poorer African American and Hispanic boys who, as adults, may face high HIV exposure risk," Gray and colleagues wrote.

    "It is also noteworthy that circumcision rates have been declining in the U.S., possibly because of lack of Medicaid coverage."

    Medicaid is the state-federal health insurance program for the poor and disabled.

    Thirty-three million people globally are infected with AIDS, which has no cure and no vaccine. HPV is the most common sexually transmitted infection in the world, with 20 million people in the United States infected. It causes cervical cancer, which kills 300,000 women globally every year.


    • #47

      July 22, 2009 -- Scientists believe they have found a "missing link" in the evolution of the virus that causes AIDS. It bridges the gap between an infection that does no harm to most non-human primates and one that kills millions of people. The suspected link is a virus that is killing chimpanzees in the wild at a disturbingly high rate, according to a study in tomorrow's issue of the journal Nature. Chimpanzees are the first primate shown to get sick in the wild in significant numbers from a virus related to HIV. They are also humans' closest relative among primates. The discovery of the disease killing chimps may help doctors to come up with better treatments or a workable vaccine for humans, experts said.

      The primate version of the virus that causes AIDS is called simian immunodeficiency virus (SIV), but most apes and monkeys that are infected with it show no symptoms of illness. "If we could figure out why the monkeys don't get sick, perhaps we could apply that to people," said study lead author Beatrice Hahn, a professor of medicine at the University of Alabama in Birmingham.

      The nine-year study of chimps in their natural habitat at Gombe National Park in Tanzania found chimps infected with SIV had a death rate 10 to 16 times as high as uninfected chimps. And postmortems of infected chimps showed unusually low T cell counts that are just like the levels found in humans with AIDS, said Hahn. And when scientists looked at the strain infecting the chimps, they found that it was a close relative of the virus that first infected humans.

      "From an evolutionary and epidemiological point of view, these data can be regarded as a 'missing link' in the history of the HIV pandemic," said AIDS researcher Dr Daniel Douek of the National Institute of Allergy and Infectious Diseases, who was not involved in the Nature study. Monkeys and apes other than chimps seem to have an evolutionary adaptation, probably at the level of their cell receptors, that allows them to survive the virus, Douek said. The infection in chimps is more recent so they haven't adapted. Hahn said chimps and people probably caught the virus the same way, by eating infected monkeys. And they both spread it the same way, through sexual activity.

      Chimps are already endangered in the wild. Many factors are causing Africa's chimp population to dwindle, said study co-author Michael Wilson, a professor of anthropology at the University of Minnesota and former director of field research at the Jane Goodall Institute in Tanzania. Hunting, loss of habitat and disease are decreasing chimp numbers and it's hard to figure out how much of a factor SIV is, he said. "It is a concern," Wilson said. "The last thing these chimps need is another source of mortality."

      Wilson, who spent years observing chimps in Tanzania as part of the study, said that when researchers realised the virus was fatal and they knew which chimps were infected, it became hard to watch some of their activities in the wild. He recalled wanting to warn one female chimp: "Don't mate with those guys ... But of course I can't do that."


      • #48

        August 3, 2009 -- A new strain of HIV has been discovered in a woman from Cameroon. It differs from the three known strains and appears to be closely related to a form of the virus recently discovered in wild gorillas, researchers reported today in the journal Nature Medicine. The finding "highlights the continuing need to watch closely for the emergence of new HIV variants, particularly in western central Africa," said the researchers, led by Jean-Christophe Plantier of the University of Rouen, France. The three previously known HIV strains are related to the simian virus that occurs in chimpanzees. The most likely explanation for the new find is gorilla-to-human transmission, Plantier's team said. But they added they cannot rule out the possibility that the new strain arose in chimpanzees and moved into gorillas and then humans, or moved directly from chimpanzees to both gorillas and humans. The 62-year-old patient tested positive for HIV in 2004, shortly after moving to Paris from Cameroon, according to the researchers. She had lived near Yaoundé, the capital of Cameroon, but said she had no contact with apes or bushmeat. The woman currently shows no signs of AIDS and is not yet receiving antiviral drug treatment, the researchers said. How widespread this strain is remains to be determined. The researchers said it could be circulating unnoticed in Cameroon or elsewhere. The virus's rapid replication indicates that it is adapted to human cells, they reported.


        • #49
          i just read that last article on the BBC.... you are very up to date


          • #50

            Samedi 8 Août 2009 -- Des chercheurs américains ont décodé la structure du génome complet du virus du sida, ce qui pourrait permettre d’accélérer la recherche pour développer de nouveaux médicaments antiviraux, selon des travaux publiés jeudi par la revue scientifique britannique Nature. Ce travail ouvre la voie ?* des recherches qui devraient favoriser une meilleure compréhension des stratégies d’infection du virus, selon les chercheurs. Le VIH-1, principale cause de la pandémie du sida, porte son information génétique dans des structures plus complexes que d’autres organismes. Le VIH – comme les virus de la grippe, de l’hépatite C et de la polio – a son information génétique stockée sur une molécule d’acide ribonucléique (ARN), un simple brin, alors que le génome des mammifères s’inscrit sur la double hélice de l’acide désoxyribonucléique (ADN). Mais l’information contenue dans l’ARN est plus complexe. Kevin Weeks (université de Caroline du Nord ?* Chapel Hill, Etats-Unis) et ses collègues livrent une large « vue aérienne » de l’architecture du génome du virus et de ses fonctions possibles, relève dans un éditorial de la revue Hashim Al Hashimi (université du Michigan, Etats-Unis). « Nous commençons également ?* comprendre les ruses du génome qui permettent au virus d’échapper ?* la détection de son hôte humain », commente Kevin Weeks. Les chercheurs montrent aussi que la formation des protéines est influencée par des éléments de la structure interne de l’ARN. Ce qui suggère que la structure même de l’ARN pourrait avoir un rôle, jusque-l?* non reconnu, dans l’expression du code génétique, selon les chercheurs.


            • #51

              September 3, 2009 -- Scientists probably know more about HIV than any other pathogen, but despite that fact, they have had frustratingly little success in applying their knowledge toward a vaccine against the virus. Now, after more than 15 years of trial and error in the field, researchers at the Scripps Research Institute and the International AIDS Vaccine Initiative (IAVI) report they have discovered two powerful new antibodies to HIV, which may potentially lead to the development of a way to immunize against the virus. While the new antibodies are not the first of the so-called broadly neutralizing antibodies that have been isolated from HIV-positive patients, they appear, at least in the lab, to be 10 times more effective at disarming the virus than earlier versions. They are also effective against a broad array of HIV strains that span nearly every continent, from Europe and North America to Asia and Africa. That would make them ideal candidates for a new vaccine — one that could actually protect people from becoming infected with HIV at all.

              In a way, it's a back-to-the-future approach. Vaccines, including many of the familiar ones that target childhood diseases such as measles and mumps, work by training the immune system to generate antibodies against a foreign bacteria or virus. Made by immune cells known as B lymphocytes, these antibodies bind to specific portions of a virus and then hamper that virus from infecting healthy cells. Eventually, the piggybacked antibody also tags the invading virus for destruction by other immune cells, known as T cells. "We looked at 162 different [HIV] viruses, and these antibodies neutralized 120 to 130 of strains from all across the world," says Dennis Burton of Scripps, the lead author of the study, published in the September 4 issue of Science. "They certainly don't get everything. But if you are able to get 80% or more of viruses circulating out there with one single antibody, that's terrific. That's really, really good, considering how variable these viruses are."

              That variability has been the biggest challenge for HIV vaccinemakers. HIV mutates so rapidly once it finds a new home in an infected patient that it's hard for researchers to keep pace and target the portions of the virus that are conserved. It was a lesson that Merck learned the hard way in 2007, when trials of its promising AIDS-vaccine candidate not only failed to protect people from acquiring HIV but in fact appeared to raise the risk of infection in inoculated people, compared with those who did not get the vaccine. (It's not clear why Merck's compound failed so miserably, but researchers believe it may have to do with the vector, an inactivated cold virus, that was used to ferry the immunity-triggering HIV proteins into the body; some people may have developed enough natural tolerance to the common-cold virus that their immune system did not react to it, or to the viral payload piggybacked on it, at all.)

              Given that recent setback, Burton's team decided on a different approach. Instead of trying to identify which portions of HIV elicited the best immune response — a strategy that has been attempted without much success in not just Merck's but other previous vaccine efforts as well — they started with a pool of antibodies they knew could neutralize HIV and then backtracked to determine how to entice the immune system into producing them. To find the most effective antibodies, Burton's team used the latest biological and computational screening techniques, which emerged from genome-sequencing technologies. They collected blood serum from 1,800 HIV-infected people from around the world, then screened these virus-laden samples against B cells to see how many of the HIV strains the immune cells would recognize. To their surprise, the B cells were able to neutralize a fair number of the viruses, but two of the antibodies produced by the cells clearly stood out as more potent than the rest.

              "This paper is important because what the authors were able to do is identify many more neutralizing antibodies than what we find in the serum of patients," says Dr. Anthony Fauci, director of the National Institute on Allergy and Infectious Disease, which raises the question, "Why don't people make antibodies to all of these HIV strains? Why isn't their blood naturally loaded with these antibodies?" One reason may be that HIV is able to hide from B cells, jealously guarding its most conserved, and therefore most vulnerable, portions from view. That would prevent the body from creating the right neutralizing antibodies against the virus. But the two new antibodies reported in Science target a less hidden region of the viral coat, so it may be possible that if a new vaccine is developed, it could stimulate the immune system to marshal a robust enough force of antibodies to stop HIV.

              The new discoveries have renewed some AIDS researchers' faith in the vaccine approach. In the lab, says Fauci, scientists know that these antibodies can effectively stop HIV in its tracks, starving it out by preventing it from binding to immune cells that provide it with the nutrients and machinery it needs to grow and reproduce. The next and perhaps greater challenge is making the right concoction of viral proteins that will stimulate the immune system to churn out these antibodies in large amounts. "Now that we have the antibodies, we have to go back and create the [immune signal] that produces these antibodies," says Seth Berkley, president and CEO of IAVI. After that, the task is to package that immune signal in the form of a usable vaccine. Says Fauci: "And that's a big catch, a second hurdle that we have not gone over yet."


              • #52
                Rachel O'Brien :

                Vendredi 25 Septembre 2009 -- Des chercheurs américains et thaïlandais ont annoncé jeudi avoir mis au point un vaccin expérimental qui réduit d'un tiers les risques de contamination par le virus du sida, au terme d'une étude portant sur 16.000 personnes qui redonne de l'espoir aux scientifiques. L'opération, présentée comme la plus importante jamais effectuée pour un vaccin contre le sida dans le monde, a été conduite par le ministère thaïlandais de la Santé et l'armée américaine. Si elle ne constitue qu'un petit pas vers la production d'un vaccin réellement efficace, elle redonne le moral ?* une communauté scientifique qui doutait de ses capacités ?* parvenir ?* ses fins depuis l'échec, en 2007, des essais du laboratoire américain Merck. "C'est la première démonstration qu'un vaccin contre le virus HIV peut protéger d'une contamination", s'est réjouit dans une vidéo conférence le colonel de l'armée américaine Jérôme Kim. "C'est une avancée scientifique très importante et cela nous donne de l'espoir qu'un vaccin efficace dans le monde entier soit possible ?* l'avenir". Le vaccin est une combinaison de deux produits testés précédemment mais qui ne s'étaient pas révélés efficaces indépendamment l'un de l'autre. Il s'agit du vaccin ALVAC du laboratoire français Sanofi Aventis, et de l'AIDSVAX produit par l'Américain VaxGen, cédé depuis ?* l'organisation Global Solutions for Infectious Diseases. Les scientifiques doivent notamment comprendre pourquoi le mélange des deux s'est révélé efficace. L'expérience a été menée depuis octobre 2003 dans deux provinces thaïlandaises sur 16.400 volontaires - tous séronégatifs et âgés entre 18 et 30 ans - dont l'exposition au risque de contamination était jugée similaire ?* la moyenne. La moitié ont reçu des produits actifs, l'autre moitié des placebos. 51 des 8.197 individus vaccinés ont été contaminés par le virus, contre 74 pour ceux qui n'ont pas été traités.

                Le sida, ou syndrome de l'immunodéficience acquise, dont le virus VIH a été identifié il y a 25 ans, est provoqué par une infection virale qui attaque le système immunitaire. Il a tué au moins 25 millions de personnes dans le monde. 33 millions de personnes sont actuellement contaminées par le virus HIV ou par le sida. Une trentaine de vaccins sont ?* l'étude sur la planète. Mais en 2007, les espoirs de voir aboutir un quart de siècle de recherche avaient été réduits ?* néant. Des essais cliniques du laboratoire américain Merck, lancés ?* grande échelle en particulier en Afrique du Sud, pays comptant le plus grand nombre de séropositifs au monde, avaient été interrompus après que les injections se furent avérées inefficaces. Jeudi, les premières réactions laissaient transparaître un certain espoir. L'Organisation mondiale de la santé (OMS) et l'Onusida ont évoqué leur "optimisme". Mais "beaucoup de travail reste ?* faire", ont-elles averti en soulignant qu'il restait notamment ?* déterminer la durée de la protection et si le vaccin était efficace sur d'autres sous-types du VIH. Sanofi Pasteur a estimé que l'étude constituait une "première démonstration concrète" qu'un vaccin pouvait "un jour devenir une réalité". "Bien que modeste, la réduction du risque d'infection par le VIH est statistiquement significative", a souligné Michel DeWilde, Senior Vice-président recherche et développement de Sanofi Pasteur. À New York, l'organisation International AIDS Vaccine Initiative (IAVI) a salué de son côté un "résultat scientifique significatif". "C'est la première fois qu'un projet de vaccin est efficace sur des humains. Jusqu'?* maintenant, nous n'avions de preuve d'une faisabilité que sur des animaux", a indiqué le président de l'IAVI, Seth Berkley.


                • #53

                  February 21, 2010 -- Health officials are considering a radical shift in the war against HIV and Aids that would see everyone tested for the virus and put on a lifetime course of drugs if they are found to be positive. The strategy, which would involve testing most of the world's population for HIV, aims to reduce the transmission of the virus that causes Aids to a level at which it dies out completely over the next 40 years. Brian Williams, professor of epidemiology at the South African Centre for Epidemiological Modelling and Analysis in Stellenbosch, said that transmission of HIV could effectively be halted within five years with the use of antiretroviral drugs (ARVs). "The epidemic of HIV is really one of the worst plagues of human history," Williams told the American Association for the Advancement of Science meeting in San Diego. "I hope we can get to the starting line in one to two years and get complete coverage of patients in five years. Maybe that's being optimistic, but we're facing Armageddon."

                  Major trials of the strategy are planned in Africa and the U.S. and will feed into a final decision on whether to adopt the measure as public health policy in the next two years. The move follows research that shows blanket prescribing of ARVs could stop HIV transmission and halve cases of Aids-related tuberculosis within 10 years. More than 30 million people are infected with HIV globally and two million die of the disease each year. While ARVs have been a huge success in preventing the virus from causing full-blown Aids, scientists estimate only 12% of those living with the infection receive the drugs. The disease is overwhelmingly prevalent in sub-Saharan Africa, which accounts for a quarter of all HIV/Aids cases globally. Half of these are in South Africa. In general epidemics, a person with HIV infects between five to 10 others before succumbing to complications of Aids. Treating patients with ARVs within a year of becoming infected can reduce transmission tenfold, enough to cause the epidemic to die out. In the trials, people will be offered HIV tests once a year, either as routine when they visit their GP, or through mobile clinics in more remote regions. Those testing positive will be put on a lifetime course of ARVs.

                  "Over the past 25 years we have saved the lives of probably two to three million people using antiretroviral drugs, but almost nothing we have done has had any impact on transmission of the disease," Williams said. "We have stopped people dying but we haven't stopped the epidemic." If patients take ARVs when they should, the amount of virus in their bodies can fall by 10,000 times, to a level at which they are extremely unlikely to pass the virus on. "The question is, can we use these drugs not only to keep people alive, but also to stop transmission and I believe that we can. We could effectively stop transmission of HIV in five years." Scientists estimate that the cost of implementing the strategy in South Africa alone will be $3 billion-$4 billion a year. The world currently spends $30 billion (£19.4 billion) a year on Aids research and treatment, a figure that some experts believe will double over the next decade.

                  Sub-Saharan Africa has seen a dramatic rise in cases of tuberculosis among HIV patients, who are also susceptible to other infections because their immune systems are weakened. "If you factor in all of the costs, in my opinion, doing this would be cost saving from day one, because the cost of the drugs would be more than balanced by the cost of treating people for all of these other diseases and then letting them die," Williams said. "We're killing probably half a million young adults every year in the prime of their life just at the point where they should be contributing to society and the cost of that to society is enormous," he added. "The only thing that's more expensive than doing this is not doing this." HIV patients in southern Africa are more likely to take ARVs when they should than people living in developed countries, according to health officials. The finding gives doctors hope that the blanket administering of drugs might suppress the virus enough that it dies out naturally. Last year, scientists reported marginal success of a HIV vaccine following a large scale trial in Thailand. The vaccine benefited only 31% of those who received it. A vaccine is generally regarded as worthwhile if it protects more than 70% of those treated.


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