A crash program to develop an AIDS vaccine may be the only way to reduce a worldwide death toll that could reach 70 million by 2020, some of the world's leading researchers say.

Twenty-four scientific leaders advanced a formal proposal in the journal Science on Thursday calling for a network of coordinated research centers dedicated to the sole purpose of developing and testing an AIDS vaccine.

Co-authors of the proposal include two Nobel prize winners, the heads of major public health departments of the U.S. government, and AIDS researchers from France, South Africa, England, Switzerland, China, India and the United Nations.

In concept, said co-author Dr. David Baltimore, the proposal is rather like a Manhattan Project against AIDS.

"In the sense it is a commitment to use the skills of the scientific community to solve a problem, it is like the Manhattan Project," said Baltimore, a Nobel laureate. "But the Manhattan Project depended on secrecy and we're doing the exact opposite."

Baltimore said the research would be conducted openly, with information and discoveries shared quickly and completely between labs.

Despite more than 20 years of effort, researchers have yet to find the ideal approach against AIDS. The human immunodeficiency virus, or HIV, that causes AIDS attacks the very cells in the body's immune system that play a key role in protecting against infection.

Most vaccines cause the production of antibodies that neutralize an invading microbe, but HIV attacks the immune system itself and antibodies made against HIV are ineffective.

Vaccines that have been tested have failed to trigger the immune system response needed to kill or control HIV, and researchers are still uncertain exactly how to prompt a vaccine-induced defense against the virus.

As a result, the plan calls for each of the labs to take a different approach in an effort to find the best route to a vaccine defense.

"Increasing the diversity of approaches and coordinating the types of vaccines entering clinical trials are fundamental to speeding global HIV vaccine development," the authors write.

Vaccines usually are developed by private pharmaceutical companies, but Baltimore said the problems and expense of developing an HIV vaccine make the traditional ways impractical.

"The pharmaceutical industry is involved, but not with the intensity that we would like," he said. "There are only a few companies that have put out an intense effort. I think part of the reason is that it is not seen as a potentially profitable enterprise."

A crash program to develop and test an AIDS vaccine, the experts said, could cost billions of dollars and take five to 10 years.

But it is an effort that humanity cannot ignore, said the experts.

AIDS now kills more people than any other infectious disease. By 2010, it's estimated there will be 45 million new infections. HIV kills people in the prime of life, causing a serve impact on a nation's economy and leaving behind millions of orphaned children.

The entire continent of Africa has been crippled by AIDS, said Baltimore, and the disease is now becoming a major health threat in Asia.

"AIDS has decimated Africa and if it spreads to the same percentage of people in India or China, it will decimate those countries," he said.

The lead author of the study is Dr. Richard D. Klausner, the former director of the National Cancer Institute.

Co-authors include Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, the chief federal AIDS research agency; Dr. Julie L. Gerberding, director of the U.S. Centers for Disease Control and Prevention; Dr. Gary J. Nabel, head of the Vaccine Research Center at NIAID; and Harold Varmus, a Nobel prize winner, former head of the National Institutes of Health and current president of the Memorial Sloan Kettering Cancer Center in New York.