Delegates in saris, kente cloth, western suits and golf shirts trickled out of the largest-ever International AIDS Conference with a sense of guarded optimism, boosted in part by speeches by luminaries such as Bill Gates, and new data on treatments and prevention strategies that will set research agendas for coming years.
Dreams of an effective vaccine remain just that for now, but many researchers said they were encouraged by some of the progress presented this year at the HIV conference, which is held every two years and brings together scientists, policy makers and activists.
"I know someone said this meeting was long on spectacle but short on science, but I don't agree," said Dr. Michael Gottlieb, a Los Angeles physician who first reported the disease that became known as AIDS 25 years ago, of the weeklong meeting that wrapped up in Toronto a week and a half ago. "I think there actually was a lot of good applied science."
Not everyone at the meeting was so upbeat.
When Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, stood on a podium to speak about the history and future of AIDS on Wednesday, a group of activists criticized the U.S. government's stand against funding needle exchange programs and its perceived preference for ones promoting abstinence. A banner read: "U.S. Govt: Put the sex and drugs back in HIV prevention!"
Later, Stephen Lewis, the United Nations' special envoy on fighting AIDS in Africa, blasted the South African government for perpetuating myths about AIDS worthy of the "lunatic fringe."
South Africa's president, Thabo Mbeki, has still not acknowledged that the human immunodeficiency virus causes AIDS, and a government-sponsored display at the meeting reportedly touted a diet of lemons, garlic and other natural foods as a treatment for the disease.
But despite these complaints, the feeling of hope was palpable as strains of "We Shall Overcome" and "This Little Light of Mine" echoed through the halls. Speakers such as Gates, the chairman of Microsoft Corp. and of a foundation that has spent $1.9 billion on AIDS, expressed hope that the tide of this virus could be turned.
"We're not yet at the midpoint of this thing, but I get very optimistic," Gates said in a public conversation with former President Clinton.
The Toronto conference showcased the most interesting developments in treatment drugs since the Vancouver conference in 1996, said Dr. Charles Farthing, chief of medicine for the AIDS Healthcare Foundation in Los Angeles.
"For doctors like me, this was a fantastic conference because I have so many options now that I can prevent almost everybody from dying," Farthing said.
The newest treatment options generated much interest at the conference because they can help people who have developed resistance to other classes of drugs that engendered excitement a decade ago. The new therapies include:
* Integrase inhibitors. These drugs, which target an enzyme in HIV known as integrase, generated the most buzz at the conference, in part because they were shown to cut the amount of virus in a person's system very rapidly.
For example, a combination of drugs that included an integrase inhibitor developed by the drug maker Merck & Co. cleared detectable levels of the HIV virus from people's blood after a month in about 65% of patients. In the same period of time, only about 25% of patients taking today's standard therapy showed clearance.
At the conference, Merck announced that it was expanding access to its experimental drug for patients who had developed resistance to other drug classes.
* Entry inhibitors. These drugs seek to keep the virus from entering a human cell by clogging a receptor called CCR5, which the virus latches onto in order to invade. Most forms of HIV get into cells using CCR5.
Preliminary results from a trial of an experimental drug called vicriviroc (by Schering-Plough Corp.) in 118 people who were not responding to antiviral regimens showed that adding the drug to a cocktail led to a nearly 100-fold drop in the amount of virus in their system in 24 weeks. The placebo group showed about a twofold drop.
Five patients in the vicriviroc groups developed malignancies such as lymphomas, compared with two in the placebo group. But a review board said there was no conclusive evidence that the drug caused these cancers, said Dr. Daniel Kuritzkes, director of AIDS research at Brigham and Women's Hospital in Boston and one of the authors on the study.
This class of drugs has encountered problems before. A trial of another entry inhibitor -- aplaviroc, made by GlaxoSmithKline -- was stopped last year when several patients suffered serious liver toxicity. But so far, no such events have been found with maraviroc, an experimental entry inhibitor made by Pfizer Inc. that is in the final stage of clinical trials.
* Vaccines, which have been eagerly awaited since the early years of the AIDS epidemic, are still making slow progress, however. Dr. Seth Berkley, chief executive of the International AIDS Vaccine Initiative, highlighted two vaccines in the later stages of testing at a media conference and declared, "We're about to enter a renaissance in AIDS vaccine research."
One vaccine, which Berkley called the more promising, uses a modified cold virus to expose the body's immune system to HIV genes. In the other trial, patients are first given a canarypox virus altered to contain some HIV genes, and then given HIV proteins in a second injection.
But several other doctors, including Dr. Mark Wainberg, director of the McGill AIDS Centre in Montreal and one of the conference co-chairs, did not share that optimism.
Although Wainberg said he certainly cheers on the development of vaccines, he worries about how quickly the virus changes and the differences between strains in different parts of the world. "Vaccines are at least 10 years off, and there was nothing at this conference that caused me to change my mind," he said. For this reason, a lot of people followed the developments in other prevention technologies with much interest.
A study on the possibility of giving people antiviral drugs before they are even exposed to HIV showed the strategy was safe and hinted toward some protection.
Researchers also presented some incremental, but significant, data on vaginal gels and other microbicides that women can use to protect themselves from becoming infected.
Results from trials of other strategies -- such as use of male circumcision or diaphragms to cut down the rate of HIV transmission -- should be available starting next year.
Wainberg said that all these developments led to a sunnier mood at the end of this conference than at the two previous ones, in Bangkok and Barcelona.
Although a vaccine (the holy grail of prevention) or medicines to wipe all HIV out of the body (the Holy Grail of treatment) remain elusive, results presented at the meeting showed that scientists were a little closer. "They put us," Wainberg said, "in good shape to start dreaming."