A nurse (L) hands out a red ribbon to a woman, to mark World Aids Day, at the entrance of Emilio Ribas Hospital, in Sao Paulo December 1, 2014. 
 
 LONDON Dec 1 Rapid evolution of HIV, the human immunodeficiency virus, is slowing its ability to cause AIDS, according to a study of more than 2,000 women in Africa. 
 
 Scientists said the research suggests a less virulent HIV could be one of several factors contributing to a turning of the deadly pandemic, eventually leading to the end of AIDS. 
 
 "Overall we are bringing down the ability of HIV to cause AIDS so quickly," Philip Goulder, a professor at Oxford University who led the study, said in a telephone interview. 
 
 "But it would be overstating it to say HIV has lost its potency -- it's still a virus you wouldn't want to have." 
 
 Some 35 million people currently have HIV and AIDS has killed around 40 million people since it began spreading 30 years ago. 
 
 But campaigners noted on Monday that for the first time in the epidemic's history, the annual number of new HIV infections is lower than the number of HIV positive people being added to those receiving treatment, meaning a crucial tipping point has been reached in reducing deaths from AIDS. 
 
 Goulder's team conducted their study in Botswana and South Africa -- two countries badly hit by AIDS -- where they enrolled more than 2,000 women with HIV. 
 
 First they looked at whether the interaction between the body's natural immune response and HIV leads to the virus becoming less virulent or able to cause disease. 
 
 Previous research on HIV has shown that people with a gene known as HLA-B*57 can benefit from a protective effect against HIV and progress more slowly than usual to AIDS. 
 
 The scientists found that in Botswana, HIV has evolved to adapt to HLA-B*57 more than in South Africa, so patients no longer benefited from the protective effect. But they also found the cost of this adaptation for HIV is a reduced ability to replicate -- making it less virulent. 
 
 The scientists then analyzed the impact on HIV virulence of the wide use of AIDS drugs. Using a mathematical model, they found that treating the sickest HIV patients -- whose immune systems have been weakened by the infection -- accelerates the evolution of variants of HIV with a weaker ability to replicate. 
 
 "HIV adaptation to the most effective immune responses we can make against it comes at a significant cost to its ability to replicate," Goulder said. "Anything we can do to increase the pressure on HIV in this way may allow scientists to reduce the destructive power of HIV over time." 
 
 The study was published on Monday in the journal Proceedings of the National Academy of Sciences (PNAS). 
 
 (Editing by Alison Williams) ||||| Image copyright SPL 
 
 HIV is evolving to become less deadly and less infectious, according to a major scientific study. 
 
 The team at the University of Oxford shows the virus is being "watered down" as it adapts to our immune systems. 
 
 It said it was taking longer for HIV infection to cause Aids and that the changes in the virus may help efforts to contain the pandemic. 
 
 Some virologists suggest the virus may eventually become "almost harmless" as it continues to evolve. 
 
 More than 35 million people around the world are infected with HIV and inside their bodies a devastating battle takes place between the immune system and the virus. 
 
 HIV is a master of disguise. It rapidly and effortlessly mutates to evade and adapt to the immune system. 
 
 Image copyright SPL Image caption HIV, in red, has infected a cell in the immune system, yellow. 
 
 However, every so often HIV infects someone with a particularly effective immune system. 
 
 "[Then] the virus is trapped between a rock and hard place, it can get flattened or make a change to survive and if it has to change then it will come with a cost," said Prof Philip Goulder, from the University of Oxford. 
 
 Weakened 
 
 The "cost" is a reduced ability to replicate, which in turn makes the virus less infectious and means it takes longer to cause Aids. 
 
 Media playback is unsupported on your device Media caption Prof Dausey, Mercyhurst University: "We have to be cautiously optimistic about this study" 
 
 This weakened virus is then spread to other people and a slow cycle of "watering-down" HIV begins. 
 
 The team showed this process happening in Africa by comparing Botswana, which has had an HIV problem for a long time, and South Africa where HIV arrived a decade later. 
 
 Prof Goulder told the BBC News website: "It is quite striking. You can see the ability to replicate is 10% lower in Botswana than South Africa and that's quite exciting. 
 
 "We are observing evolution happening in front of us and it is surprising how quickly the process is happening. 
 
 "The virus is slowing down in its ability to cause disease and that will help contribute to elimination." 
 
 Drug bonus 
 
 The findings in Proceedings of the National Academy of Sciences also suggested anti-retroviral drugs were forcing HIV to evolve into milder forms. 
 
 It showed the drugs would primarily target the nastiest versions of HIV and encourage the milder ones to thrive. 
 
 Prof Goulder added: "Twenty years ago the time to Aids was 10 years, but in the last 10 years in Botswana that might have increased to 12.5 years, a sort of incremental change, but in the big picture that is a rapid change. 
 
 "One might imagine as time extends this could stretch further and further and in the future people being asymptomatic for decades." 
 
 The group did caution that even a watered-down version of HIV was still dangerous and could cause Aids. 
 
 Image copyright SPL 
 
 HIV originally came from apes or monkeys, in which it is frequently a minor infection. 
 
 Prof Jonathan Ball, a virologist at the University of Nottingham, told the BBC: "If the trend continues then we might see the global picture change - a longer disease causing much less transmission. 
 
 "In theory, if we were to let HIV run its course then we would see a human population emerge that was more resistant to the virus than we collectively are today - HIV infection would eventually become almost harmless. 
 
 "Such events have probably happened throughout history, but we are talking very large timescales." 
 
 Prof Andrew Freedman, a reader in infectious diseases at Cardiff University, said this was an "intriguing study". 
 
 He said: "By comparing the epidemic in Botswana with that which occurred somewhat later in South Africa, the researchers were able to demonstrate that the effect of this evolution is for the virus to become less virulent, or weaker, over time. 
 
 "The widespread use of antiretroviral therapy may also have a similar effect and together, these effects may contribute to the ultimate control of the HIV epidemic." 
 
 But he cautioned HIV was "an awfully long way" from becoming harmless and "other events will supersede that including wider access to treatment and eventually the development of a cure". ||||| By Randy Dotinga 
 
 HealthDay Reporter 
 
 MONDAY, Dec. 1, 2014 (HealthDay News) -- New research in Africa suggests that the AIDS virus is getting smarter about evading the immune system while evolving into a less contagious and less lethal infection overall. 
 
 In the country of Botswana, at least, "anyone who is newly infected now with HIV is less likely to suffer disease than if they had been infected 20 or 30 years ago," said study co-author Philip Goulder, a research immunologist with the University of Oxford in England. "If this process continues, HIV will cause less and less disease." 
 
 The research has caveats. It relies on research from just two countries, both in Africa, and might not apply to the rest of the world. And some of its findings are based on mathematical models of how HIV, the virus that causes AIDS, is evolving. Still, the study is "good news," Goulder contended. 
 
 Thanks to natural selection, some viruses actually evolve to make the host less sick over time, Goulder explained. 
 
 "One might intuitively imagine that the most successful viruses are the ones that cause maximum disease and kill their hosts most rapidly," Goulder said. "However, this is not necessarily the case, since if the hosts die quickly, the chances of the virus being transmitted reduce very rapidly. So, in fact, the most successful pathogens tend to be the ones that have evolved over time to cause very little disease." 
 
 The study, published Dec. 1 in Proceedings of the National Academy of Sciences, was launched to see if that's happening to HIV. The researchers focused on the evolution of the virus in two countries severely hit by AIDS -- Botswana, where the disease infected people earlier and more widely, and South Africa. 
 
 In Botswana, the researchers found, the virus has become more adept at bypassing the immune systems of people infected by it. However, this "appears to be beneficial in that there is a cost to HIV from this process of adaptation," Goulder said. "The cost is that HIV replicates less efficiently than before." 
 
 In addition, the researchers suggest that powerful anti-HIV drugs are also pushing the virus to become less virulent. 
 
 "These findings are most likely to apply to Botswana and sub-Saharan Africa, where the global epidemic is concentrated," Goulder said. Things could be different in other places like the United States, he said. 
 
 Christian Brander, a research professor with the Institute for AIDS Research in Barcelona, Spain, called the study "outstanding." 
 
 Scientists should wonder whether the same thing -- a virus that becomes less transmissible over time -- is happening to Ebola, Brander said. 
 
 "The virus has to change," he said, "but these mutations have ramifications." 
 
 More information 
 
 The University of California, Berkeley, has more information on the evolution of the AIDS virus. 
 
 Copyright © 2014 HealthDay. All rights reserved. 
 
 ||||| Factors that influence the virulence of HIV are of direct relevance to ongoing efforts to contain, and ultimately eradicate, the HIV epidemic. We here investigate in Botswana and South Africa, countries severely affected by HIV, the impact on HIV virulence of adaptation of HIV to protective HLA alleles such as HLA-B*57. In Botswana, where the epidemic started earlier and reached higher adult seroprevalence than in South Africa, HIV replication capacity is lower. HIV is also better adapted to HLA-B*57, which in Botswana has no protective effect, in contrast to its impact in South Africa. Modelling studies indicate that increasing antiretroviral therapy access may also contribute to accelerated declines in HIV virulence over the coming decades. 
 
 Abstract 
 
 It is widely believed that epidemics in new hosts diminish in virulence over time, with natural selection favoring pathogens that cause minimal disease. However, a tradeoff frequently exists between high virulence shortening host survival on the one hand but allowing faster transmission on the other. This is the case in HIV infection, where high viral loads increase transmission risk per coital act but reduce host longevity. We here investigate the impact on HIV virulence of HIV adaptation to HLA molecules that protect against disease progression, such as HLA-B*57 and HLA-B*58:01. We analyzed cohorts in Botswana and South Africa, two countries severely affected by the HIV epidemic. In Botswana, where the epidemic started earlier and adult seroprevalence has been higher, HIV adaptation to HLA including HLA-B*57/58:01 is greater compared with South Africa (P = 7 × 10−82), the protective effect of HLA-B*57/58:01 is absent (P = 0.0002), and population viral replicative capacity is lower (P = 0.03). These data suggest that viral evolution is occurring relatively rapidly, and that adaptation of HIV to the most protective HLA alleles may contribute to a lowering of viral replication capacity at the population level, and a consequent reduction in HIV virulence over time. The potential role in this process played by increasing antiretroviral therapy (ART) access is also explored. Models developed here suggest distinct benefits of ART, in addition to reducing HIV disease and transmission, in driving declines in HIV virulence over the course of the epidemic, thereby accelerating the effects of HLA-mediated viral adaptation.
– HIV has evolved into a less potent disease than it was 30 years ago, says a new study, and scientists say it might one day turn into a relatively harmless version of itself. British researchers drew the conclusions after studying HIV patients in Botswana and Africa, reports HealthDay. HIV arrived in Botswana a decade earlier than in South Africa, and today's version in Botswana is slower and less likely to cause AIDS. Twenty years ago, for example, the typical HIV patient in Botswana got AIDS in 10 years. Now it takes 12.5 years, "a sort of incremental change, but in the big picture that is a rapid change," says one of the lead researchers from the University of Oxford. As the BBC explains, scientists see it as a natural evolution: Eventually, HIV runs into people with natural immunity and has to adapt to survive, and this "watered down" version begins to spread. "In theory, if we were to let HIV run its course then we would see a human population emerge that was more resistant to the virus than we collectively are today," says a virologist at the University of Nottingham. "HIV infection would eventually become almost harmless," though he cautions that he's talking about "very large timescales." In its coverage, Reuters notes an HIV milestone: For the first time, the number of new annual infections is lower than the number of new HIV-positive people getting treatment, "meaning a crucial tipping point has been reached in reducing deaths from AIDS. "