For a study this week in the journal Nature Medicine, Kathleen Collins and her team have uncovered another of HIV’s dirty tricks: the virus can hide out in bone marrow cells and lie in wait for the right time to strike.
In recent years, drugs have reduced AIDS deaths sharply, but patients need to keep taking the medicines for life or the infection comes back, she said. That’s an indication that while the drugs battle the active virus, some of the disease remains hidden away to flare up once the therapy is stopped [AP]. One place the researchers already knew HIV could hide was inside resting T cells. However, Collins says, she thought T cells alone didn’t offer a complete picture of the virus’ ability to play hide-and-seek.
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It’s a big year for South Africa: Less than four months remain until the first matches of the World Cup, when much of the planet’s attention will turn to the country. But being under the spotlight of international sport makes it difficult to hide a country’s less glamorous bits, as China and Canada have found out trying to shield pollution and addiction problems from the glare of the last couple Olympiads. In June, the microscope will turn to South Africa and its ongoing AIDS crisis.
This month one of the country’s health leaders has renewed his call for blanket HIV testing and anti-retroviral drug dispersal to all patients, which he says can stop the AIDS epidemic once and for all–without having to find a vaccine against the virus or a cure for the disease.
Brian Williams’s idea isn’t new. The former World Health Organization figure, who is now one of South Africa’s top health officials, came out with a paper more than a year ago explaining his model for how effective universal testing and immediate therapy could be. But this week at the American Association for the Advancement of Science meeting in San Diego he expounded on his proposal: “The epidemic of HIV is really one of the worst plagues of human history…. 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” [The Guardian].
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The United States will end its long-standing ban that prevents foreigners with HIV from entering the country. President Obama announced the change on Friday, saying that the exclusionary rule had been “rooted in fear rather than fact.” The policy has been in place for 22 years, and was enacted at a time when people still wondered whether HIV could be transmitted through physical or respiratory contact. It will officially be repealed at the start of 2010.
The ban applied both to tourists wishing to visit the United States and to foreigners who hoped to live and work here. Only about a dozen other countries still bar people with HIV or AIDS from entering. “If we want to be a global leader in combating H.I.V./AIDS, we need to act like it,” Mr. Obama said. “Now, we talk about reducing the stigma of this disease, yet we’ve treated a visitor living with it as a threat” [The New York Times].
Gay advocates said the ban also discouraged travelers and some foreigners already living in the United States from seeking testing and medical care for H.I.V. infection. “The connection between immigration and H.I.V. has frightened people away from testing and treatment” [The New York Times], said Rachel Tiven of the advocacy group Immigration Equality.
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Image: flickr / Doug Letterman
Sigh. Less than three weeks after health officials convened a press conference in Thailand to announce a rare piece of good news in the hunt for an HIV vaccine, some scientists are asking whether the results were overstated.
The large clinical trial of the vaccine was a modest success, but it was plenty exciting for HIV vaccine researchers who have been waiting for years for any sign of progress. The U.S. Army and Thai researchers who collaborated on the trial found that the vaccine lowered the risk of infection by about 31% — a “modest benefit,” they said, but one that was statistically significant, suggesting the finding was not a fluke [The Wall Street Journal, blog]. But the press conference did not trumpet another analysis of the data, which included only those volunteers who carefully followed the experiment’s rules and got the full regimen of six shots at the right times. This second analysis showed a 26 percent rate of protection, and a much higher chance that the benefit was a fluke.
Some scientists say both analyses should have been revealed during the September announcement, and claim that the way the press conference was handled further undermines the research. “The press conference was not a scholarly, rigorously honest presentation,” said one leading HIV/AIDS investigator, who like others asked that his name not be used. “It doesn’t meet the standards that have been set for other trials, and it doesn’t fully present the borderline results. It’s wrong” [ScienceInsider].
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Two HIV vaccines on trial in Thailand have shown some limited success in protecting people from the virus that causes AIDS. And in the hard-fought world of HIV research, that qualifies as a major breakthrough. Says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases: “For more than 20 years now, vaccine trials have essentially been failures…. Now it’s like we were groping down an unlit path, and a door has been opened. We can start asking some very important questions” [The New York Times].
The Thailand trial studied two vaccines that had already proven ineffective on their own. But people who received both vaccines were 31 percent less likely to get HIV, compared to people who received a placebo. This partial protection is a good step, but it’s also a puzzle to scientists who don’t understand why the vaccines only worked for some people.
In the trial, more than 8,000 volunteers received the vaccines, and an equal number received placebos. After three years, 51 people from the vaccinated group had been infected, compared to 74 people in the placebo group. While the numbers are small, researchers say they’re statistically significant.
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Although researchers searching for an HIV vaccine have been down the path of optimism and disappointment many times before, a new finding has nevertheless brought fresh hope to the flagging effort. Researchers have discovered two antibodies that can effectively fight back most strains of the HIV virus, and say they’ll now try to make a vaccine that can teach the human body to produce these antibodies.
The weapons in question are called broadly neutralising antibodies…. These are antibodies that deactivate a wide range of HIV strains—which is particularly important for an effective vaccine, because HIV is so variable [The Economist]. Researchers found the two new antibodies after screening blood samples from 1,800 people around the world who were infected with HIV but hadn’t yet developed AIDS; the two antibodies both came from an African donor. Of these two potent antibodies, one neutralized 127 of 162 HIV strains and the other neutralized 119.
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In an effort to stop the spread of HIV, public health officials are considering initiating a program that would encourage circumcision for all newborn boys in the United States.
Studies have shown that heterosexual adult men reduce their risk of HIV by 50 percent by being circumcised. “We have a significant H.I.V. epidemic in this country, and we really need to look carefully at any potential intervention that could be another tool in the toolbox we use to address the epidemic…. What we’ve heard from our consultants is that there would be a benefit for infants from infant circumcision, and that the benefits outweigh the risks” [The New York Times], says CDC epidemiologist Peter Kilmarx.
On the other hand, circumcision has not been shown to reduce HIV risk among men who have sex with men–the U.S. demographic with the highest risk of contracting the virus. And the American Academy of Pediatrics does not currently endorse routine circumcision, as it doesn’t consider the procedure essential to a baby’s well-being. Finally, nearly four-fifths of American men are circumcised, so it’s not clear whether a policy recommending circumcision would have much impact.
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Image: flickr/ Topdog1
The genome of an HIV virus is a truly twisted thing, but now for the first time researchers have traced its every fold and contour. By mapping its entire structure, they hope to gain a greater understanding of how the virus operates, and potentially accelerate the development of drug treatments [BBC News]. Usually geneticists focus on the sequence of genes that comprise an organism’s genome, but recent evidence suggests that the structure can also play a role in how it functions.
Like many other viruses, the HIV genome consists of single-strand RNA, rather than the double-stranded DNA found in most animals. Though scientists have identified HIV’s genes and their order, just one-fifth of its genome has been described in precise spatial detail. That’s important because genomes don’t look anything like the neatly linear, bar code-like pictures returned by basic sequencing techniques. In reality, genomes are arranged in intricate, three-dimensional loops and whorls. And just as a list of machines isn’t very useful without a description of their arrangement on a factory floor, structure matters [Wired.com].
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In the first known case of its kind, scientists have identified a strain of HIV that can be traced to gorillas, not chimpanzees, according to a report in Nature Medicine. The new strain was detected in a Cameroonian woman living in France.
Previous strains of HIV virus type 1, the main type of the disease, have been shown to have arisen from chimpanzees, and researchers found that the new virus is dissimilar enough from previously known strains that it cannot be detected by standard HIV tests. After genetic analysis, scientists also found that the infection is closely related to gorilla simian immunodeficincy virus, or SIVgor, the gorilla version of HIV. Genetic analysis of the woman’s virus shows that it is so closely related to SIVgor that “the most likely explanation for its emergence is gorilla-to-human transmission” [Bloomberg], says co-author Jean-Christopher Plantier.
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Scientists have long known that chimpanzees and other nonhuman primates can become infected with simian immunodeficiency virus, or SIV, a variant of HIV. It was thought, however, that only Asian macaque monkeys could die from the infection. But a new study published in Nature contradicts this assumption by finding that the virus can also be deadly to chimpanzees, humans’ closest relatives.
Some wild primates appear to have developed a way to keep SIV from becoming deadly, and scientists had hoped that studying chimpanzees could reveal how this mechanism works, possibly opening to the door to a human remedy. The new results suggest that it will not be possible to find the key to HIV immunity in the chimpanzee genome, as scientists had hoped. However, the study… sets the stage for researchers to gain insight into how HIV and SIV cause disease in their hosts by studying the responses of different primates to the viruses [Nature News].
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In September 2007, HIV research faced a serious setback: Scientists found that a promising HIV vaccine was actually increasing the rate of HIV infection, and the so-called STEP vaccine trial was immediately halted. The failure had a ripple effect, and caused researchers to call off another vaccine trial that operated on a similar principle. Since then, researchers have developed multiple explanations for why the vaccine upped the risk of infection. Now two new studies presented in Nature Medicine refutes the latest of these hypotheses, which gives researchers valuable information but ultimately leaves the mystery unsolved.
The recent theory held that some people responded more strongly than others to a component of the vaccine tested in the STEP trial, making them more vulnerable to HIV, which attacks immune cells that are actively responding to a pathogenic threat [Nature News]. Because the vaccine was constructed on the modified backbone of the virus that causes the common cold, the theory posited that white blood cells called helper T-cells jumped into action to combat this infectious particle. Unfortunately, HIV targets these T-cells, scientists reasoned, so vaccination actually gave HIV a larger target. This would explain why vaccination increased the risk of HIV infection.
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Circumcising men who are infected with HIV does not protect their female partners from the deadly virus, researchers have found. The Uganda-based study was stopped early due to “futility,” the researchers wrote in a study published in The Lancet, when it became clear that the women were not benefiting. The outcome was disappointing because circumcision has been shown to drastically reduce infection rates in men. But the researchers said that wide-scale circumcision is so effective in protecting men that [it] will still likely benefit women indirectly by reducing circulation of the virus in general [Reuters].
In 2007, the World Health Organization concluded that circumcising males reduced female-to-male transmission of the HIV virus by about 60 percent. The foreskin of the penis, which is removed during circumcision, is rich in cells that are particularly easy for the virus to infect. The theory is that removing this source of vulnerable cells makes infection more difficult [Reuters].
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All’s fair in the fight against the AIDS virus–including medical sneak attacks. Researchers have devised a novel strategy to attack HIV by completely bypassing the immune system and instead tricking the muscles into producing virus-fighting proteins.
The quest for an HIV vaccine has been given a bad prognosis recently, due to increasing agreement that the human immune system isn’t clever enough to outsmart the ever-changing surface of the virus [Technology Review]. But using the new technique, researchers were able to protect monkeys from infection by the simian immunodeficiency virus (SIV), the animal virus most closely related to HIV. While lead researcher Philip Johnson cautions that there’s no guarantee that the vaccination process will work in humans, he’s eagerly looking forward to human trials in a few years.
Most efforts at blocking AIDS have sought to stimulate the body’s immune system to produce antibodies that fight the disease. This model has worked for diseases such as measles and smallpox. It hasn’t done as well with HIV/AIDS; test vaccines have failed to produce a protective reaction. So Johnson decided to try something different. “We used a leapfrog strategy, bypassing the natural immune system response that was the target of all previous HIV and SIV vaccine candidates,” Johnson said [AP].
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Unconventional is the theme of the Bill & Melinda Gates Foundation‘s latest round of endorsements. The foundation on Monday awarded 81 five-year research grants of $100,000 to scientists pursuing bold ideas that could lead to breakthroughs, focusing on ways to prevent and treat infectious diseases, such as HIV, malaria, tuberculosis, pneumonia and diarrheal diseases [AP].
One grant, for example, will be awarded to Rutgers University’s Eric Lam, who is working to develop tomatoes that can deliver antiviral drugs. Another grant will fund a British research team attempting to compile a library of all possible mutations of HIV with the ultimate goal of a vaccine that can protect against many variant forms of the virus. In the US, [one researcher will receive] a grant to see if shooting a laser at a person’s skin before administering a vaccine can enhance immune response [Telegraph].
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The initiative begun by former president George W. Bush to stop the ravages of AIDS in Africa has saved more than one million lives, according to a new report. The study tracked AIDS deaths and HIV infections in 12 African countries getting aid under the President’s Emergency Plan for AIDS Relief, or PEPFAR, during the four years after it was launched in 2003 as a five-year, $15 billion effort…. “It has averted deaths — a lot of deaths — with about a 10 percent reduction compared with neighboring African countries” [Reuters], said study coauthor Eran Bendavid. That reduction translates to about 1.1 million lives saved.
However, the study also found that the initiative had no effect on the prevalence of the disease, suggesting that it has been more effective at keeping infected people alive than in preventing new infections. Critics of the program said it didn’t put enough money toward prevention of HIV/AIDS. About a fifth of the funds were dedicated to prevention, and a third of that had to be used for abstinence-only programs. Congress reauthorized the program last year, removing the abstinence-only stipulation and increasing funding to $48 billion [San Jose Mercury News].
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