# News this Week

Science  13 May 2011:
Vol. 332, Issue 6031, pp. 772
1. # Around the World

1 - Northern California
Science Is Lacking in California Bay Delta Conservation Plan
2 - Washington, D.C.
White House Tempers Impact of China Ban
3 - Paris
Scientists in Growth Hormone Scandal Found Blameless
4 - Frankfurt, Germany
European Science Foundation Members Fumble Merger Plans
5 - Tokyo
Japan Scraps Nuclear Plan

## Northern California

### Science Is Lacking in California Bay Delta Conservation Plan

A draft plan to restore the California Bay delta east of San Francisco contains major scientific gaps, according to a new report from the National Research Council (NRC).

The delta provides drinking water to about 25 million people and irrigation to the Central Valley, a major agricultural zone. But pumping the water out has helped drive down the estuary's fish populations; at the same time, water demand is increasing.

In search of a sustainable solution, members from interest groups—such as wildlife agencies and irrigation districts—in 2006 began work on the Bay Delta Conservation Plan (BDCP). Its centerpiece is a 65-km-long tunnel designed to ferry water from the Sacramento River north of the delta directly to consumers, thus avoiding the destructive pumping of water from the estuary.

But the draft BDCP fails to scientifically evaluate the consequences for the region's ecosystem, the NRC panel concluded. This analysis is now under way, but the plan has other problems, the report says. Among them: fragmented science and a lack of detail, such as how much water would be channeled through the tunnel. The nearly $150 million endeavor will have to fill in these blanks by the end of 2013, when the final plan is due. http://scim.ag/ca-water ## Washington, D.C. ### White House Tempers Impact of China Ban The Obama Administration has interpreted a congressionally imposed ban on scientific collaboration with China in a way that may limit its impact. At a hearing last week, John Holdren, the president's science adviser, argued that it doesn't apply to any diplomatic agreements between the two countries. The ban, which applies to activities involving NASA or the White House Office of Science and Technology Policy, is part of the recently passed budget for the rest of fiscal year 2011 (Science, 29 April, p. 521). Holdren told Representative Frank Wolf (R-VA), chair of a House of Representatives spending panel and author of the language, that “the prohibition should not be read as prohibiting interactions that are part of the president's constitutional authority to conduct negotiations. But we will be looking at that on a case-by-case basis.” After the hearing, Holdren noted that “my assumption is that there will be some activities that will be precluded.” Wolf is unlikely to let the matter rest, however. Don't be surprised if an expanded version of the ban shows up in next year's spending bill. ## Paris ### Scientists in Growth Hormone Scandal Found Blameless A French appeals court last week threw out charges of involuntary manslaughter and other crimes against two scientists involved in a growth hormone scandal that has led to the deaths of 125 children from Creutzfeldt-Jakob disease (CJD), a fatal brain illness. The case has dragged on since the early 1990s, and two of the original defendants have died. But the lawyers for the victims' families say they intend to take the case to France's highest court of appeal. From 1959 to 1988, France treated 1698 growth-deficient children with hormone derived from pituitary glands taken from human cadavers, a practice that has been linked to the transmission of CJD, a prion disease. Prosecutors faulted the scientists involved for not doing enough to prevent the infections, and for switching to the much safer synthetic growth hormone later than other countries. But the appeals court confirmed a lower court's 2009 ruling that “no fault” had been committed by biochemist Fernand Dray (pictured), who was in charge of purifying the material at the Pasteur Institute, and pediatrician Elisabeth Mugnier, who was in charge of collecting the pituitary glands and monitoring treatment. The verdict noted that no one could have detected the contamination at the time. http://scim.ag/CJD-case ## Frankfurt, Germany ### European Science Foundation Members Fumble Merger Plans A plan to create a new body that would provide a powerful voice for science policy across Europe was thrown into disarray last week. The idea was to merge two existing organizations—the European Science Foundation (ESF) and an informal body with the unfortunate acronym EuroHORCs (European Heads of Research Councils)—into a single outfit that would help develop European science strategy, coordinate national research activities, and lobby on behalf of national funding agencies. The new organization, with the working title Science Europe, was planned as something of a counterweight to the European Union, which funds around 5% of the continent's research but is the dominant body in European science policymaking. But some objected to the exclusion from Science Europe of societies that are now part of ESF; others complained that current ESF funding programs would be scrapped. Last week, the planned merger failed to gain enough votes at ESF's general assembly. ESF is now discussing how to proceed. “Everyone will have to take a deep breath,” says ESF President Ian Halliday. http://scim.ag/merger-fail ## Tokyo ### Japan Scraps Nuclear Plan In the wake of the Fukushima nuclear disaster, Japan's prime minister, Naoto Kan, announced this week that his government is abandoning its plan to build 14 new reactors and generate half the country's electricity from nuclear power. Instead, Kan said, Japan will emphasize renewable energy production and conservation. Nuclear plants now produce 30% of Japan's electricity. The move came 4 days after Kan urged the operators of the Hamaoka nuclear power plant to cease operations for “the safety and security of the Japanese people.” The plant, which sits near a fault line in a high-risk seismic area 200 kilometers southwest of Tokyo, is protected from tsunamis only by sand dunes. The Chubu Electric Power Co. complied on 9 May. The shutdown will add to Japan's electricity-generating woes; the country is already facing potential shortages this summer. 2. # Random Sample ## Hoping for a Ticket to Ride Care for a cruise on a hydrocarbon lake? Or a journey beneath the surface of Mars? How about hopping on and off a comet? NASA selected those three possibilities last week as candidates for its next Discovery mission, to be launched in 2016. The Titan Mare Explorer (TiMe, right) would splash down on a large methane-ethane lake on Saturn's moon Titan, float there for 3 months, and send back data on the lake's composition and its role in Titan's methane cycle. The Geophysical Monitoring Station (GEMS, left) would monitor seismic activity on Mars, probe heat flow from the interior, and track variations in the planet's wobble. The third mission, Comet Hopper, would land on a comet several times and monitor changes as the comet interacts with the sun. The three competing groups have each been awarded$3 million to flesh out their proposals; NASA will pick the winner next year. The cost: no more than $425 million. ## They Said It “The Q'ero Nation knows its history, its past, present and future is our Inca culture and we don't need any so-called genetic study to know who we are. We are Incas, we always have been and always will be!” —Benito Machacca Apaza, president of the Community of Hatun Q'eros, in a letter objecting to plans to collect DNA from the remote tribe in Peru as part of the National Geographic Society's Genographic Project. http://scim.ag/qeros-dna ## By the Numbers 10.1 Billion — The world population by 2100, according to new projections by the United Nations. It had previously forecasted the population peaking in the low 9 billions, then declining. http://scim.ag/_worldpop 8.2% — The percentage of Americans with asthma as of 2009, according to the U.S. Centers for Disease Control and Prevention. That's up from 7.3% in 2001. 2.6% — The prevalence of autism among children aged 7 to 14 in Goyang, South Korea. That's more than twice the estimated rate in the United States, according to an online paper in The American Journal of Psychiatry. ## Missing in Action Who won the 1916 Nobel Prize in physics? Trick question: The Nobel Committee, harried by World War I, left it vacant. But a petition circulating to dozens of U.S. universities aims to fill that gap with Henry Moseley, an x-ray specialist. In 1913, Moseley, just 25 and then at the University of Manchester in the United Kingdom, determined that each element's spot on the periodic table equaled the proton count in its nucleus, uniting chemistry and atomic physics and giving the table a sound theoretical basis. Moseley likely would have won a Nobel but died serving with the British Army at Gallipoli in 1915. Nobels cannot be awarded posthumously. But as the centennial of Moseley's death approaches, David Harder, a science enthusiast and former UPS warehouse worker living in California, wants the Nobel Committee to take this unprecedented step. Others, notably Isaac Asimov, suggested the idea before, Harder says, “but since nothing was getting done, I decided I'd take care of it.” So on 1 April (“terrible date to postmark them,” he admits), Harder mailed petitions to 104 top chemistry and physics departments in 28 states, asking scientists for support. So far he's gotten no response: “It's really bummed me out.” Harder knew he might struggle to enlist people, partly because one could argue that Nikola Tesla, Lise Meitner, or others deserve vacant prizes, too. But Moseley's “fantastic leap forward” stands above all, Harder argues. “We are not talking about rewriting history,” his letter pleads, “merely correcting an error.” 3. # Newsmakers ## Three Q's As the head of Howard Hughes Medical Institute's (HHMI's) new documentary film unit, Michael Rosenfeld hopes to team up with researchers around the world to bring the excitement of scientific discovery to a broader audience. HHMI has committed$60 million over 5 years to finance film projects. Rosenfeld, a television journalist who produced the popular Explorer series during more than 2 decades at National Geographic, begins his job in July.

Q:Why has HHMI launched this initiative?

Both public and cable TV have had a lot of pressure on their financial budgets. The initiative will make it possible to produce high-end, ambitious projects. A good film can provide clarity about scientific discoveries and what they mean. That's especially crucial in the areas that are often debated … like vaccines or nuclear power.

Q:How do you balance substance and entertainment?

Make the scientific process really engaging. It's the job of the film to make people understand why the process is so important and what makes it so interesting and what the stakes are. A great producer can take an intellectual puzzle and turn it into a mystery story and get the person hooked.

[Volcanologists and I] took a chopper up to the edge of the lava lake in Hawaii. We went out and collected lava samples, and … my [rubber-bottomed] shoes melted out under me. Suddenly I'm essentially standing in my bare socks. But the only injury was to my pride!

4. # The Emerging Race to Cure HIV Infections

1. Jon Cohen

Timothy Ray Brown's startling fate has pushed to the front a daunting research challenge that long seemed a fool's errand

In May 1995, after learning that a former partner had become infected with HIV, Timothy Ray Brown, then 29, decided he should take the test himself. Brown, an American living in Berlin and working as a translator, felt perfectly healthy, had not had sex with his former partner in years, and 5 years earlier had tested negative. “It was a bit of a shock,” Brown says, when he found he was infected.

At the time, HIV was seen as a death sentence. AZT and two other antiretroviral drugs (ARVs) had come to market, but the pills typically delayed death from AIDS for only a few years. The damage to Brown's immune system wasn't yet life-threatening: His CD4 count, which refers to the white blood cells that HIV destroys, had dropped to under 400 cells per microliter. (Normal is 600 to 1200.) But his doctor recommended immediate treatment, and Brown started taking AZT.

Within a year, cocktails of new ARVs proved so effective that an HIV infection became a chronic disease. Brown changed regimens repeatedly to take advantage of the advances, but he suffered from many side effects, from headaches and night sweats to diarrhea and vomiting. In 2000, his doctor suggested he take a break and stop all medication.

By 2002, Brown's CD4 level had plummeted to 250, 50 shy of an AIDS diagnosis, which indicates that a person's immune system can no longer contain otherwise harmless opportunistic infections. He started treatment again, easily tolerating a cocktail of new-generation ARVs. The amount of virus in his blood, the so-called viral load, dropped to an undetectable level on the most sensitive test available.

Four years later, Brown, then 40, received a second devastating diagnosis: He had developed acute myeloid leukemia, a highly lethal cancer, unrelated to HIV. Because of the complexity of treating leukemia in an HIV-infected patient, his doctor referred him to Campus Benjamin Franklin, a large clinic affiliated with the Free University of Berlin. Gero Hütter, an oncologist and hematologist, took the case.

Three rounds of chemotherapy caused liver and kidney failure and high fevers; Brown became so ill that the hospital put him in the intensive care unit and induced a coma. “While I was in the coma for 16 hours, they thought I was going to die and told my boyfriend they didn't know if I would make it,” Brown says. But he fully recovered. In September 2006, Brown took a monthlong trip to Italy and upon his return started working out at the gym again. “I was doing fine,” he recalls.

Hütter, who has since moved to the University of Heidelberg, warned his patient that leukemia often returns, and that if it did, the next line of treatment was a bone marrow transplant to replace his stem cells. Then Hütter, who had never treated an HIV-infected patient before, proposed a radical idea: What if a stem cell transplant could eliminate both the leukemia and HIV?

Hütter knew from reading the literature that some rare individuals were highly resistant to becoming infected with HIV because of a mutation in their CD4 cells. HIV establishes an infection by attaching to both the CD4 receptor and a second one on the cell known as CCR5. A mutation in the CCR5 gene known as δ32, which causes no obvious harm, bars the cellular doors to HIV. Hütter suggested to Brown that if they had to do a transplant, they might as well try to find a δ32 donor. “I told him we don't know what will happen, but there might be a chance we'll get rid of the HIV,” Hütter says.

Brown at first wasn't interested. “I thought I had got rid of the leukemia because the chemotherapy had worked,” Brown says. “And I figured that I always had the medication to fall back on for HIV, and I could probably take it for 50 years and do OK.” But in early 2007, his leukemia relapsed, and he gave Hütter the green light to look for a δ32 donor. After screening 62 possibilities for a genetic match that Brown's immune system would tolerate, Hütter found a German man living in the United States who had inherited the δ32 mutation from both parents. They transplanted Brown in February 2007, a procedure that required first destroying his immune system with drugs. He stopped taking his ARVs.

Eleven months later, his leukemia returned again, but his HIV remained undetectable. Brown received a second transplant from the same donor, this time first ablating his immune system with drugs and whole-body irradiation.

Today, Brown remains free of leukemia. And although he has not taken ARVs for more than 4 years, the most sophisticated labs in the world cannot find any HIV in his body

## Proof of concept

The AIDS epidemic surfaced in June 1981, and the virus has since infected more than 60 million people, killing half of them. Brown, who became widely known in the media as the “Berlin patient” after Hütter publicly described the case in 2008, is the only living human, a growing consensus contends, to be cured.

Since 2008, there's been widespread leeriness about oversimplifying Brown's case and hyping the prospect of an AIDS cure. And Brown's treatment clearly does not offer a road map for many others. After all, the expensive, complex, and risky transplant only made sense because Brown was dying from leukemia. Nor is it clear exactly which components of the extensive transplant regimen cleared the virus from his body.

But Brown's case has moved the much-ridiculed cure idea onto the most scientifically solid ground it has yet occupied, say leading AIDS researchers. Brown's case showed for the first time that it is possible to rid the body of the virus—even from the minuscule reservoirs where the virus can hide out for years, evading both the immune system and ARVs. His astonishing turnaround also raised hopes that other, more practical drugs and immune system modulators might find and destroy every last bit of virus—or at least reduce it to such low levels that people no longer need ARVs.

There are skeptics who say Brown's virus may still come back. At first, even Hütter would not say Brown had been cured, pointing out that a cancer patient has to be free of disease for 5 years before an oncologist will use that term. But he is increasingly willing to use the “c” word, as are other leading researchers.

“Some people pooh-pooh it, but I think it's a game changer,” says James Hoxie, a virologist at the University of Pennsylvania. “It's put the word ‘cure’ in the vocabulary. I don't care if it's n = 1. It shows that it's possible.” Steven Deeks, an HIV/AIDS clinician at the University of California (UC), San Francisco, who has put efforts to cure the disease on the front burner, says, “A lot of people were interested in cure research before the Berlin patient, but he is a proof of concept. That had a big impact on the field.”

Millions of new dollars are being devoted to what some call “a race” to find a cure. The U.S. National Institutes of Health (NIH) last November solicited proposals for an $8.5-million-a-year collaborative grant to search for a cure, and several high-powered consortia applied. NIH last month added another$4.5 million to the cure research pot with the announcement of new grants to develop therapies that will allow people to stop taking ARVs for prolonged periods. The Bill and Melinda Gates Foundation, the California Institute for Regenerative Medicine, and the Foundation for AIDS Research has each issued cure-related grants. The push for a cure is further intensified by limitations of even the best ARVs and the extraordinary cost of providing them to everyone in need for decades on end.

Christine Katlama, who heads the AIDS clinical research unit at the Pitié-Salpêtrière Hospital in Paris, said she hasn't felt this buoyed about the prospects of helping HIV-infected people since the arrival of powerful ARVs—“highly active antiretroviral treatment,” or HAART—15 years ago. “For many of us who were for a long time in the field of HIV, it's a very exciting time,” she told the 200 attendees at the International AIDS Society's first-ever meeting devoted to cure research, which was held in Vienna last July.

## Purging reservoirs

In 1996, Time named AIDS researcher David Ho its “Man of the Year,” in no small part because he had dared to proclaim that HAART might eliminate HIV from a person's body. Ho, head of the Aaron Diamond AIDS Research Center in New York City, calculated that given the half-life of immune cells, if HAART completely suppressed the virus for 3.2 years, eradication would likely occur. But in the spring of 1997, Robert Siliciano's group at Johns Hopkins University in Baltimore, Maryland, reported a pivotal discovery that torpedoed Ho's simple cure idea. It also introduced a formidable challenge to curing the disease that continues to this day.

Siliciano's group identified the existence of pools of “resting” CD4 cells that harbor HIV in their chromosomes but do not produce new viruses unless they are called into action. These latently infected cells serve as the immune system's memory and can live for years. Siliciano and Ho together published a study in the 14 November 1997 issue of Science (p. 1295) showing that people on HAART who had “undetectable” levels of HIV on standard tests for up to 30 months all had reservoirs of about 1 million latently infected cells. Siliciano, his wife Janet, who is also at Johns Hopkins, and co-workers later estimated that it would require 72 years of HAART to clear those stubborn reservoirs.

As bleak as his assessment was, Siliciano's discovery pointed the way to a new strategy for curing AIDS. He and other investigators reasoned that if they could wake up those resting cells, they would start to divide and force HIV out of hiding. This, theoretically, would “purge” the reservoir as the production of HIV would either kill the cells directly or mark them for immune attack. ARVs would mop up any new HIVs before they could infect virgin cells.

A few groups, including Ho's, soon tried to purge reservoirs by jolting the immune system with agents like the chemical messenger interleukin-2 and a monoclonal antibody. Virologist Douglas Richman of UC San Diego says this strategy caused the equivalent of toxic shock syndrome. “They almost killed their patients,” Richman says.

They almost killed cure research, too. But with Brown's success and a more refined understanding of reservoirs, efforts to purge them are again the cornerstone of cure strategies. Several prominent research groups have begun experimenting with a variety of different approaches, including using drugs already on the market to treat other diseases, tweaking immune systems, and engineering gene therapies to mimic Brown's transplant.

All these early trials are big gambles, and no one is expecting to discover a cure anytime soon. But with the field's momentum and better funding, hopes are high that progress—which at this point would mean simply showing that an intervention reduced a latent reservoir by any amount—could surface in the next year or two. And luckily for the field, there are plenty of HIV-infected people willing to join these cure studies, which often means agreeing to highly unusual experimental interventions and the extremely invasive tests needed to assess whether they have had an impact.

## Acute angles

At 8 a.m. one October morning in 2010, a researcher dressed in a coat and tie entered the apheresis room at the memorial hospital run by the University of North Carolina (UNC), Chapel Hill. But the man, who is in his mid-50s, had not come to study the patients in this room—he was one of them. Over the next 4 hours, a machine would drain the blood from his body two times, 10 liters in all, and replace it, separating out billions of his white blood cells for later analysis. The researcher, who asked that his name not be used, had joined a unique study at the university led by UNC molecular virologist David Margolis that hopes to shrink the HIV reservoir.

Four years earlier, the researcher had gone to see his doctor after repeated night sweats and a fever spiking to 40°C. “I told him I'd been involved in risky behavior and should be tested for HIV,” recalls the man, who is married and has children. The antibody test came back negative.

The researcher knew that an HIV infection could take several weeks to trigger a detectable antibody response used in the stock test, but that the polymerase chain reaction could pluck out the viral genetic material itself. He requested a PCR test, which confirmed that an acute HIV infection explained his flulike symptoms. “The first thing I thought about was suicide, the second thing I thought about was suicide, and the third thing I thought about was suicide,” he says.

Within a month, the man joined a trial at UNC to assess whether HAART offered extra benefits if people started treatment during acute infection. In particular, HIV destroys CD4s in the gut during the first few weeks of infection, and evidence suggests that when people wait to start HAART—which is standard care—those cells never completely return. This in turn causes a chronic state of inflammation that leads to long-term health problems such as cardiovascular disease and diabetes, even in people who have undetectable levels of virus while on HAART.

The UNC team is now following 80 people who started ARVs during acute infection, and from that cohort, they have recruited 20 volunteers, including this man, to take part in a cure trial that began in March. Margolis and his team reasoned that people treated during the acute phase should have smaller pools of latently infected cells than those who start HAART later, and the smaller the reservoir, the easier it should be to drain.

The UNC study adds to standard HAART a Merck drug, SAHA, already on the market to treat cutaneous T-cell lymphoma. In addition to its cancer-fighting abilities, SAHA tinkers with the structure of chromosomes and kick-starts transcription of DNA (see sidebar), which Margolis and others are hoping will flush latent HIV out of hiding, leading those cells down the road to ruin.

Determining whether SAHA works requires an extraordinary commitment from the infected researcher and the 19 other participants: These otherwise healthy people must repeatedly undergo the grueling, time-consuming apheresis procedure to quantify their minuscule reservoirs and assess whether they have shrunk. “It's a big hassle,” Margolis says. “It's not like you can take a little blood from someone's arm and know something. … We're trying to measure a rare event, and to measure a rare event you need a lot of cells.”

Daria Hazuda, vice president of virus and cell biology at Merck Research Laboratories in West Point, Pennsylvania, shares Margolis's enthusiasm that SAHA might shrink reservoirs. But Hazuda, who is part of a collaboration led by Margolis that's bidding for the new NIH cure money, also urges people to keep hope in check. “From an experimental medicine point of view, that's a great approach,” Hazuda says. “Is that going to be the answer by itself? Having worked so many years on HIV therapy, it would seem to me a single molecule to address reservoirs is a bit naïve.”

## Multipronged attack

Don Howard, a 47-year-old management consultant in San Francisco, started on HAART the day after he tested positive in 1996. “At some level, I'm a control freak,” says Howard, who is so fit and radiant he could be in advertisements for energy drinks. “The notion that I could take something to make it all better was extremely appealing.” Now he's first in line for one of the cure studies getting under way at San Francisco General Hospital, where he has been Deeks's patient for 15 years.

Like the UNC group, Deeks and his collaborators hope to purge reservoirs with drugs that trigger transcription, but they have several other strategies in the works that hit the virus from other angles. The trial participants again will come from a group of patients who started treatment during acute infection, and no one has been on HAART longer than Howard. “It suggests he's closer to eradication than anyone in our cohort,” Deeks says.

Howard's motivation to join the study has more to do with curiosity and a desire to contribute than concern about long-term damage from the virus or drugs. “It's more intellectually interesting than it is practically compelling,” he says. Nonetheless, he, too, is willing to undergo deep probes of his body to quantify his reservoir. One of the most difficult challenges researchers face is that reservoirs can pool in tissues that are difficult to access. Howard has already had lymph nodes excised and bone marrow extracted, and he may undergo biopsies of his gut, which is home to an estimated 80% of the body's CD4 cells.

Deeks and his collaborators contend that reservoirs persist by different mechanisms, which will require different strategies to deplete them. One possibility is that even in people like Howard who have undetectable virus on HAART, HIV constantly replicates at low levels, creating new latently infected cells and perpetually refilling reservoirs. Adding another powerful ARV to the HAART cocktail, then, might shut down that production.

Although several “intensification” studies have failed to detect any impact on HIV, Deeks remains convinced that the approach shows promise. “You can't cure people by getting rid of low-level replication, but if you want to cure people, you have to get rid of it,” Deeks says. He also points to an intensification study reported in the April 2010 issue of Nature Medicine that found hints of an effect. Led by Maria Buzón the Autonomous University of Barcelona in Spain, the study has sparked debate and divided Deeks and his like-minded colleagues from Margolis, Siliciano, Richman, and many others who are convinced that standard HAART has reached the limits of what ARVs can do.

After upping the subjects' ARVs, Deeks's team plans to begin testing the drug disulfiram, also known as Antabuse, which is on the market to treat alcoholism. Siliciano's lab recently discovered in test-tube experiments that disulfiram, like SAHA that Margolis is testing, turns on HIV transcription in latently infected cells, although the mechanism is not clear.

Triggering transcription with drugs like disulfiram or SAHA carries risks, especially when tested in healthy people like Howard. On top of the direct toxicities of the drugs, Eric Verdin, a virologist at the Gladstone Institute of Virology and Immunology and one of Deeks's collaborators, cautions that inducing transcription could stir endogenous retroviruses from their slumber. These remnants of ancient infections constitute 8% of the human genome, and no one knows what havoc they might wreak. “A lot of mechanisms used to suppress endogenous retroviruses are the same mechanisms that suppress HIV,” Verdin says.

In a completely different tack, Deeks's group wants to tweak the immune system to help cure people. One strategy aims to purge reservoirs by hijacking an immune actor with the macabre name programmed death 1 (PD-1). This receptor on the surface of CD4 cells helps slam the brakes on cell division, maintaining the latent state. A test-tube study presented at the 2011 Conference on Retroviruses and Opportunistic Infections (CROI) by two of Deeks's collaborators, virologist Nicolas Chomont and immunologist Rafick-Pierre Sékaly of the Vaccine & Gene Therapy Institute of Florida in Port St. Lucie, showed that when they blocked the PD-1 receptor with an antibody, the cells coughed up gobs of HIV.

Another approach assumes that purge strategies will not eradicate HIV but that shrinking reservoirs in combination with fortifying the immune system could lead to a “functional” cure that allows people to stop ARVs. “There might be a threshold level where the immune system is able to contain the virus,” Verdin says. To that end, the group has joined the multisite Eramune trial (see table, p. 789), which pairs intensification with an HIV vaccine made by NIH.

## Designer genes

In a clinical sense, Matt Sharp differs in several ways from Howard and the HIV-infected researcher in North Carolina. “I've been through the ringer and knocked on death's door,” says Sharp, 54, an HIV/AIDS educator who lives in Brisbane, near San Francisco. His face is sunken from lipodystrophy, a side effect of the first-generation anti-HIV drugs. For many years, HIV outwitted his drugs and the virus battered his immune system. He has had two hospital stays because of severe pneumonia and has also battled bouts of tuberculosis (TB) and wasting disease. But he, too, is taking part in pathbreaking cure studies.

Sharp, who works with the San Francisco–based advocacy group Project Inform, learned of his HIV infection in October 1988 when he was a ballet dancer in Oklahoma City. “Who knows when I was infected,” he says. “We all were having unsafe sex because we didn't know any better. Those were back in the days you'd get a sexually transmitted disease and get a shot and you were back into the mix of things the next few days. There wasn't any consideration of death, so we didn't take it that seriously.” His initial CD4 count: 409. “It scared the hell out of me,” he says.

Despite starting treatment a year after he tested positive, in 1991 Sharp developed extrapulmonary TB, a dangerous form of the disease linked to HIV. He moved to San Francisco and plugged in with activist groups that kept him abreast of treatment advances, and as new ARVs became available, he changed his regimen repeatedly. Yet by the mid-1990s, his 6-foot-tall frame had withered from 185 pounds to 155. In 1996, Sharp's CD4 cells dropped to as low as 15. After quickly developing resistance to the protease inhibitors that then formed the cornerstone of HAART, he joined a highly unconventional trial and received a thymus transplant, which putatively would rebuild his immune system. “It wasn't anything that probably helped,” he says.

In 2001, Sharp became one of a small group of people to take injections of Fuzeon, the first drug to come to market that jams the HIV entry process. “It was very painful, but I was willing to do it because I had no options,” he says. His viral load became undetectable for the first time. His good fortune lasted all of 1 week. Five years ago, he added raltegravir to his regimen, and his HIV has subsequently remained undetectable with a CD4 count hovering around 300. “It isn't great, but it got me out of the danger zone,” he says.

Last June, Sharp joined one of two gene therapy studies now under way that tries to mimic Brown's success in relatively healthy HIV-infected people. The small trial, led by Jacob Lalezari of Quest Clinical Research in San Francisco and Ronald Mitsuyasu at UC Los Angeles, sidesteps the need to find an immunologically matched donor who has the CCR5 mutant and does not use ablation. Sharp, known as patient 01-203, and eight other participants first went through leukapheresis to remove about 10 million of their CD4 cells, which the researchers then modified with adenoviruses engineered to contain what are known as zinc-finger nucleases. Developed by Sangamo BioScience in Richmond, California, the zinc-finger nucleases clip out a specific small sequence of DNA in the CCR5 gene, rendering cells incapable of producing a functioning version of the receptor.

After expanding the cells in culture, the researchers in September infused Sharp with about 2 billion of his own rejiggered CD4s. Sharp sat in the audience at the 2011 CROI when Lalezari revealed early results from patient 01-203 and five others. “There are a lot of unanswered questions, obviously, but it was incredibly exciting to see my data points,” Sharp says.

As Lalezari explained, the gene therapy modified only about 25% of the cells that they infused, but the CCR5 mutants persisted in Sharp and four of the others for more than 3 months. Rectal biopsies showed that the modified cells had trafficked to the gut, indicating that they had spread to this critical viral hangout. CD4 counts jumped an average of 100 cells. There were no serious, lasting side effects.

This does not come close to a cure. As Lalezari noted, the fraction of modified CD4s eventually dropped to just over 5%, in contrast to Brown, who had 100% of his CD4 cells destroyed and replaced with CCR5 mutants. Lalezari cautiously concluded that the therapy ultimately “offers the hope of providing a protected reservoir of CD4+ T cells that are resistant to HIV infection.”

In a best case scenario, the modified cells will copy themselves indefinitely and evolve into the predominant group. If HIV does replicate in people like Sharp after they have received the gene therapy, the virus should selectively infect and kill the normal CCR5+ cells, and the population of CCR5− mutants would steadily rise. A report in the August 2010 issue of Nature Biotechnology showed that just such a selection occurred in mice engineered to contain a humanlike immune system. Led by Paula Cannon of the University of Southern California in Los Angeles, the experiment used the same Sangamo zinc fingers to cripple CCR5. The transplanted mice then received injections of HIV, and 12 weeks later, the CCR5− mutants almost completely replaced the CCR5+ cells. “And guess what: The virus goes away,” says Cannon, who in October 2009 won a \$14.5 million grant from the California Institute for Regenerative Medicine to take a similar approach into the clinic with collaborators at the City of Hope in Duarte, California.

Ultimately, transfused patients will have to stop taking ARVs to see whether their modified immune systems are strong enough to contain the virus. “The great news is we can always put people back on ARVs if the gene therapy fails,” Cannon says. “It's a no harm, no foul strategy.”

In a small trial, similar to the Quest study, that's run by Carl June of the University of Pennsylvania, two patients who received the zinc-finger gene therapy went off ARVs, with intriguing results. As June reported at the 2011 CROI, HIV returned in both patients, but in one, the virus took 10 weeks to surface, a signal that the modified cells made life more difficult for HIV.

Sharp has no interest in going off his medication. The infusion has boosted his CD4s from the dangerously low 281 to the 600 range—the highest they have been since he was diagnosed 23 years ago. He's quick to point out that it's unclear whether the CD4s are functional and improving his health, but he is convinced that, come what may, his contribution will help advance this “very sexy area of research.” “Those of us who have survived this long with HIV are able to look back and say, ‘Why shouldn't there be a cure?’” Sharp says. “I'm so passionate about this because I want to see a cure before I die.”

## Beginning of the end

If researchers do eventually find a widely applicable cure for HIV, the process likely will resemble Brown's rough-and-tumble life, which has seen a remarkable success set against a backdrop of dramatic setbacks. “We are really at the very rudimentary stages,” says UC San Diego's Douglas Richman. “If there is going to be success—and I'm optimistic—it's going to be 1 to 2 decades.”

The field will receive a big boost in July with NIH injecting millions of new dollars to up to two collaboratory groups working on cure research. There's also a high-profile campaign led by the International AIDS Society and its president-elect, Françoise Barré-Sinoussi—who won the Nobel Prize for co-discovering HIV—to organize the research agenda and then seek more funding. “We are in a period of economic crisis, but if we work together, we can do a lot,” Barré-Sinoussi says. On the advocacy front, the Philadelphia-based AIDS Policy Project is aggressively pushing the agenda, lobbying the U.S. Congress and NIH to make cure research a top priority.

Brown, who recently moved to San Francisco, says he initially did not imagine his transplant of CCR5 mutant cells would have much impact on others. “At first, I was like, nobody can get this, it's not very practical, and I don't think anybody could use it for curing HIV.” But he now sees his singular triumph as having played a catalytic role in advancing the once-laughable idea that research could discover a cure for this intractable infection, and he's grateful for the chance to give back. “I'd like to be able to continue to tell people about my situation,” says Brown, who hopes to write a memoir. “It's a feeling that I'm doing some good for the world.”

5. # Understanding HIV Latency to Undo It

1. Jon Cohen

With reservoirs of latently infected cells in the spotlight as the central obstacle to a cure, attention is focusing on the fine details of how HIV does this deep dive and stays submerged.

Twenty-five years ago, when HIV still went by the names of HTLV-III and LAV, researchers recognized that the AIDS virus could lie dormant inside human chromosomes, which they erroneously suggested might explain the time lag between infection and disease. Today, with reservoirs of latently infected cells in the spotlight as the central obstacle to a cure (see main text, p. 784), attention is focusing on the fine details of how HIV does this deep dive and stays submerged. “We really need to understand what maintains latency in order to figure out how to reverse it,” says Douglas Richman, a virologist at the University of California, San Diego. “Right now, it's sort of coarse guesses.”

HIV, unlike herpesviruses, carries no gene that pushes cells into a narcoleptic state. “Latency is not a biological property of the virus,” says Eric Verdin, who studies HIV dormancy at the Gladstone Institute of Virology and Immunology in San Francisco, California. “Latency only becomes relevant because drugs can now suppress 99% of HIV replication, and that's what is left.”

HIV typically stumbles into a latent state when it infects an actively dividing CD4 white blood cell that then downshifts into a “resting” gear. These resting CD4s can lounge around for years until they are called into action and start dividing, at which point the HIV genes will be expressed along with the CD4 cell's own genes. Much effort has gone into characterizing the specific subsets of memory cells that make up the reservoir, as the distinction could prove critical to purging them.

Virologist Nicolas Chomont and immunologist Rafick-Pierre Sékaly of the Vaccine & Gene Therapy Institute of Florida in Port St. Lucie reported in the August 2009 issue of Nature Medicine that 85% of the reservoir consists of two distinct lineages of CD4s known as “transitional” or “central” memory cells. This finding was hugely influential, as it showed that the reservoirs of each lineage persist by different mechanisms: Central memory cells live for decades, and infected transitional memory cells persist by cloning themselves through a process called homeostatic proliferation. “As we try to get rid of them, we'll have to use different strategies,” Chomont says.

Other researchers have probed the interior of cells to better understand how proteins, enzymes, and both human and viral DNA all work together to keep HIV silent. Chromosomes tightly pack DNA, wrapping it around proteins called histones. Expression of genes, including those inserted by trespassers like HIV, takes place when these complexes uncoil (see illustration). Specifically, as DNA unspools from histones, protein sherpas guide a suite of transcription factors to genes, which then make the amino acids that form proteins. The most popular purge strategies today aim to selectively induce HIV DNA to uncoil.

One potential way to massage histones so they let loose and allow transcription to begin: protect the acetyl groups that bind to them. Enzymes known as histone deacetylases (HDACs) constantly remove these acetyl groups, which helps keep HIV latent. SAHA, a purge drug now in clinical studies (see table), inhibits HDACs.

A half-dozen other molecular mechanisms that contribute to latency are also possible targets to purge reservoirs. DNA methylation gums up histones, so blocking that process may unspool virus. Human protein complexes sequester critical transcription factors in different parts of the cell, and drugs might free the factors from bondage, allowing them to reach the viral DNA. After transcription begins, several other proteins elongate the new HIV being expressed, and spurring them along could help flush latent virus from cells, too.

Recent advances in laboratory models of latency, including artificial infection of memory CD4 cells and “humanized” mice, are clarifying finer points of how HIV stays quiescent and identifying novel purge drugs. “We have incredible tools now, and these technologies were not available 10 years ago,” says Vicente Planelles, a virologist at the University of Utah in Salt Lake City, who developed a new latent cell system.

Just as antiretroviral drugs had little impact against HIV until several compounds simultaneously attacked the virus at different stages of its life cycle, purging reservoirs may ultimately require a cocktail of interventions that undoes latency from multiple angles. “We have to find some combination to tickle the cell and the virus such that the virus can be expressed without vastly affecting all of the other uninfected cells in the body, and that's going to be tricky,” says David Margolis, a virologist at the University of North Carolina, Chapel Hill, who has done pioneering studies with HDAC inhibitors. “This is going to be a long, difficult thing to figure out.”