LA JOLLA, Calif. (AP) _ Dr. Jonas Salk, the medical pioneer who developed the first vaccine to prevent polio's crippling rampage and later tried to devise a treatment for AIDS, died Friday. He was 80.

Salk died of heart failure at Green Hospital of Scripps Clinic in La Jolla at 12:23 p.m., said Anita Weld, a spokeswoman for the Salk Institute. He had been hospitalized earlier in the day complaining of shortness of breath.

Salk spent a lifetime stubbornly pursuing his ideas _ first for a polio vaccine and later for a vaccine-like AIDS treatment _ even when they drew skepticism from other researchers.

``There have to be people who are ahead of their time,'' Salk once said. ``And that is my fate.''

Working at the University of Pittsburgh in the 1950s, Salk became a hero to millions of Americans when he ignored scientific doubters and used killed virus to develop the first polio vaccine.

During the first half of the 20th century, epidemics of paralytic poliomyelitis swept the United States repeatedly. Polio viruses infected thousands of Americans annually, causing widespread fear, killing some young victims and condemning many others to iron lungs, leg braces and years of rehabilitation.

Salk's injectable vaccine was declared effective in 1955, and polio's toll plunged. ``What had the most profound effect was the freedom from fear,'' Salk said in 1995, as he prepared to celebrate the 40th anniversary of the announcement.

Dr. Albert Sabin's live-virus vaccine _ swallowed on a sugar cube _ was approved in 1961. Many experts believe it is more effective, and it ultimately gained favor, although Salk's vaccine is still used.

Because of Salk's vaccine, ``a generation learned to view health as a birthright, assuming that doctors could provide a cure for any ailment if it were attacked with enough boldness and enough money,'' Jane S. Smith wrote in a magazine adaptation of her book, ``Patenting the Sun: Polio, the Salk Vaccine and the Children of the Baby Boom.''

Salk moved to California, where in 1963 he established the Salk Institute for Biological Studies in La Jolla, a San Diego suburb.

The institute became a leading biomedical research center, although over the years it was beset by money troubles, bitter internal rifts and the departures of some top-notch scientists.

Salk conducted research on multiple sclerosis and cancer before retiring from his own laboratory in 1984. He continued to maintain offices at the institute and, in 1986, co-founded Immune Response Corp. of Carlsbad, Calif., to search for an AIDS vaccine.

The vaccine really was a treatment to prevent or delay development of AIDS symptoms in people already infected by the AIDS virus. Salk also hoped to eventually develop a true vaccine to prevent uninfected people from contracting the deadly virus.

Again, there were doubters. Salk modeled his AIDS vaccine after his polio vaccine, using killed AIDS virus. Skeptics argued the approach wouldn't work or carried a risk of making patients develop AIDS symptoms.

Early tests seemed to support Salk's approach, although years of research were expected before its effectiveness could be established or disproved.

``My own view is we will overcome,'' he said in 1995.

``I am a perennial optimist,'' he said. ``We certainly have the knowledge. The question is whether we have the wisdom.''

Salk promised to be among the first uninfected people to receive his AIDS vaccine, just as he injected himself with experimental influenza vaccine in 1942 and his polio vaccine in 1952.

In recent decades, Salk often awoke at night and wrote thousands of pages of philosophical musings. Published accounts said he believed the voice of evolution was speaking through him. He published three books of his philosophy: ``Man Unfolding'' in 1972, ``The Survival of the Wisest'' with his son Jonathan in 1973 and ``Anatomy of Reality'' in 1983.

Jonas Edward Salk was born in New York City on Oct. 28, 1914, the oldest of three sons of a garment industry worker.

Salk worked after school and garnered scholarships to pay for his education, earning an undergraduate degree at City College of New York in 1934 and a medical degree at New York University in 1939.

Salk married Donna Lindsay the same year. They had three sons, but were divorced in 1968. In 1970, he married painter Francoise Gilot, the longtime companion of late painter Pablo Picasso.

After a 1939-1940 internship at New York's Mount Sinai Hospital, Salk took his first research position at the University of Michigan, where he helped develop flu vaccines.

Salk moved the University of Pittsburgh School of Medicine in 1947, and two years later became director of the virus research laboratory, where he searched for a polio vaccine.

President Franklin D. Roosevelt's battle with polio had focused attention on the disease. One of the president's associates headed the National Foundation for Infantile Paralysis, known as the March of Dimes, which helped finance Salk's research.

The nation's worst polio epidemic was in 1952. The next year, Salk announced development of an experimental vaccine.

Salk, his wife and their sons were among the first to receive injections. In 1954, more than 1.8 million school children _ nicknamed Polio Pioneers _ participated in a nationwide test of the vaccine during history's largest medical experiment.

Salk's name became a household world, splashed across magazine covers and newspaper front pages.

Salk won many awards, but many scientists considered his contribution overrated. The only Nobel Prize for polio research went to Harvard virologist John Enders and colleagues who made vaccine development possible by showing the polio virus could be grown in culture.

Salk's work ``was pure kitchen chemistry,'' longtime rival Sabin said in 1990. ``Salk didn't discover anything.''

Salk blamed professional jealousy for criticism, saying, ``Albert Sabin was out for me from the very beginning.''

In a statement released after Sabin's death in 1993, Salk was more conciliatory. He called Sabin's passing ``a great loss,'' saying, ``The effect of his contributions toward the control of polio will endure long in the future.''

Many experts favor Sabin's vaccine, saying it is more effective at providing lifelong immunity and also spreads immunity to contacts of vaccinated people. Yet it carries a minute risk of causing polio, and produces the only known U.S. polio cases today.

Salk said his vaccine was safer. But only weeks after it was declared effective, officials discovered one manufacturer produced some vaccine tainted by live polio virus that infected 204 people, paralyzing three-quarters and killing 11. The government ordered manufacturers to filter the vaccine, a step Salk said reduced its effectiveness.

He is survived by his wife and three sons, Peter, Jonathon and Darrell.