Jonas Salk

American immunologist

• Born: October 28, 1914
• Birthplace: New York, New York
• Died: June 23, 1995
• Place of death: La Jolla, California

Salk developed the first effective vaccine for polio, and he marshaled the nation’s resources to help eradicate the disease.

Early Life

Jonas Salk (JOH-nehs sahlk) was the firstborn child of Daniel B. Salk and Dora Press. His father was a garment maker, and both of his parents encouraged their children to do well in school. Salk attended Townsend Harris High School for the gifted and received his B.A. from College of the City of New York in 1934. He received his M.D. from New York University in 1939 and interned at Mount Sinai Hospital, where he studied immunology. Salk was recognized as an able scientist by his teachers, and during World War II he was a participant in the U.S. Army’s effort to develop an effective vaccine for influenza. He continued this interest in his first academic appointment at the University of Michigan, developing such a vaccine with his more senior colleague and former mentor, Thomas Francis, Jr. This established Salk’s reputation professionally as an ambitious, bright, and innovative scholar who could organize a laboratory and work well under pressure.

Salk was restless and wanted independence from the projects of his senior colleagues so that he could try out some of his own unconventional ideas. He astounded his peers by accepting a position at the University of Pittsburgh Medical School, which, at that time, had no record of basic research in medicine. Salk got the space he needed and rapidly put together a team of laboratory workers to help him study infectious diseases. Not intimidated by authority, Salk used his managerial skills and cultural breadth to convince philanthropists and university administrators to equip his laboratory. His driving energy resulted in the publication of many important papers that caught the attention of the National Foundation (March of Dimes) and its director, Daniel Basil O’Connor. The National Foundation had for many years supported treatment and rehabilitative programs for paralytic polio victims. Salk was one of many younger investigators whom O’Connor hoped to recruit for the research that would lead to a vaccine for that dreaded disease.

Life’s Work

Salk’s greatest contribution to immunology was his insight that the killing of a virus by chemical treatment need not profoundly alter the antigenic properties of the virus. Any foreign material in a body can serve as an antigen and provoke the body’s immune system to form antibodies to attack it. This is one of the body’s major defenses against the invasion of bacteria and viruses. A virus may have complex proteins that coat its deadly infectious nucleic acid. Chemical treatment by formaldehyde may damage some of the genes of the virus so that they cannot multiply in the body, but they may not appreciably change the shape of the surface proteins of the virus. It is the surface proteins, and not the inner core of genes contained in the viral nucleic acid, that provoke antibody formation.

Salk’s success in developing a vaccine for polio depended on the discoveries of many other researchers in immunology and virology. Originally polio could only be grown in live monkeys. Attempts in the 1930’s to use a vaccine prepared from the killed extracts of infected monkey brains resulted in the deaths of several children from meningitis and other reactions. It was also erroneously thought that polio grew only in nerve tissues, but infected humans produced large amounts of viruses in their feces, suggesting that it also grew in the intestines. John F. Enders and his colleagues succeeded in growing polio virus in tissue culture using embryonic cells, a major breakthrough that led to their being awarded a Nobel Prize in 1954. Polio also turned out not to be one virus but at least three different types of viruses, each type having many different strains, some highly infectious and others only weakly so. It was this need to type the polio viruses that brought O’Connor to Pittsburgh. Salk developed new methods to type the viruses rapidly and new methods to grow the viruses in large quantities. He realized that this work could not be done with a few animals and he organized a large laboratory, heavily funded, to maintain and use thousands of monkeys for his experiments. Salk made good use of the facilities and support; he soon proved his hunch that the antigenic properties of killed polio virus were not impaired by the formaldehyde treatment of the viruses.

Two additional findings were important for Salk’s future work in developing a polio vaccine. Isabel Morgan Mountain succeeded in immunizing monkeys against polio by using formaldehyde-killed virus. Hilary Koprowski used live viruses whose properties had been attenuated or weakened by passage through rats; he fed twenty-two human subjects with the altered virus, and none showed symptoms, although all had developed antibodies against the fully infectious strain of polio virus.

Salk rejected two prevailing views at the time. Many immunologists believed that purified antibody, gamma globulin, would be effective in preventing polio. Gamma globulin, however, was expensive, and it afforded protection for only a short time. Many other immunologists were convinced that a killed virus would not work or that it could not be purified without contamination of the proteins from the cells on which it grew. Salk proved that these two views were mistaken; with the backing of the National Foundation, he prepared the purified killed polio virus vaccines against all three types of polio. Although the virus was rendered inactive after three days, Salk kept the virus in formaldehyde for thirteen days to guarantee that no live virus was present. By 1954, all the difficulties were resolved, and Salk began the crucial human experimentation to confirm the results obtained on monkeys. He and his laboratory workers immunized themselves and their families and then began field-testing the vaccine. The virus proved better than 90 percent effective. The first seven million doses of the vaccine were administered in 1955. A contaminated source from a California pharmaceutical firm was noticed, and the trials were held up until the purification procedures were standardized. Salk then initiated a nationwide program from 1956 through 1958. Almost immediately after this massive program of immunization, the United States was polio-free.

Salk’s killed virus vaccine required four injections, one for each type plus a booster. Additional boosters were necessary as the antibody levels gradually fell. The National Foundation, aware of this possibility, had also backed Albert Sabin to develop a live polio vaccine. The live vaccine, which then required fewer visits to a physician for booster doses, replaced the Salk vaccine. The killed virus vaccine does not cause polio in its recipients or in individuals who have never been vaccinated; the live vaccine, however, occasionally does cause polio in family members or neighbors who have never been vaccinated. For this reason, Salk urged the use of killed vaccine in areas where compliance with vaccination requirements was inadequate. Although live vaccine was more frequently used in the years following Salk’s campaign, polio had already been defeated and in the public’s mind Salk had become a national hero. Among the many honors showered on him was the Lasker Award in 1956 and the Presidential Medal of Freedom in 1977.

Salk’s popularity with the National Foundation and with philanthropists led him to a second major venture. He proposed an institute for biological research that would permit the most talented scientists in the world to carry out research that would lead to new advances in knowledge beneficial to health and human happiness. The Salk Institute for Biological Studies was founded in 1960, and a building for it opened in 1963. The building, chiefly funded by the National Foundation, was constructed at La Jolla, a suburb of San Diego noted for its beautiful scenery and beachfront. The Salk Institute attracted many Nobel laureates; the freedom to do full-time research and thinking was a major feature of its design. Salk thought of the institute as an experiment in the sociology of science, with a primary mission to study and initiate modern trends in biology tempered with a conscience for humanity. Among the seven original resident fellows of the Institute was Jacob Bronowski, a mathematician turned philosopher, whose television series Ascent of Man reflected the optimism of the Salk Institute the conviction that knowledge of the universe enriches both human understanding and human welfare. Salk maintained a laboratory to study multiple sclerosis, and he also devoted much of his energy to writing books about the philosophy and social role of science. In 1995, Salk emerged from retirement to develop a therapeutic AIDS vaccine for HIV-positive patients.

Significance

Salk’s national immunization campaign in 1956-1958 administered more than two hundred million doses of killed vaccine without a single individual becoming infected with the disease. This remarkable achievement reflected Salk’s talent for establishing quality control as he shifted from a single laboratory to the national level in carrying out his project. The disease was particularly frightening to parents, who witnessed the devastating paralysis it produced in schoolchildren and the helplessness of its most severely affected survivors, who had to live in “iron lungs,” expensive and bulky machines that kept them breathing. The disease had also taken on national importance as Americans admired the courage of President Franklin D. Roosevelt, who had survived polio and went on to guide the nation through the Great Depression and World War II while confined to a wheelchair.

Salk represented a new generation of scientists who required funded research to accomplish their goals. Directing a large laboratory with many technical assistants and advanced students involves management skills, inspired leadership, the ability to write convincing grant applications and progress reports, and a personality that thrives on hard work and the occasional successes that careful scientific research yields. Salk was a model of this new type, but he was also unique in extending his efforts to involve an entire nation in his enterprise.

Bibliography

Carter, Richard. Breakthrough: The Saga of Jonas Salk. New York: Trident Press, 1965. This popular biography covers Salk’s life through 1965. Salk’s energy and personality are well depicted, although specific experiments are only mentioned and not analyzed.

Kluger, Jeffrey. Splendid Solution: Jonas Salk and the Conquest of Polio. New York: G. P. Putnam Sons, 2004. Although the book focuses on Salk, Kluger also describes the widespread fear of polio and the effects of the disease in the years before a vaccine was created and details the efforts of other scientists who sought to eradicate the disease.

Oshinsky, David M. Polio: An American Story. New York: Oxford University Press, 2005. Oshinsky’s history of polio in the United States focuses on the 1950’s, when Salk and Albert Sabin were embroiled in an intense competition to discover a cure for polio.

Salk, Jonas. Anatomy of Reality: Merging of Intuition and Reason. New York: Columbia University Press, 1983. Salk relates metabiological ideas to biological and cultural evolution. He proposes more efforts to view life and the universe from both rational and intuitive, especially value-laden, perspectives.

‗‗‗‗‗‗‗. Man Unfolding. Edited by Ruth N. Anshen. New York: Harper & Row, 1972. Salk introduces the idea of biological dualisms as attributes of the human condition, whose unresolved conflicts lead to social unrest and conflict. He uses biological processes as guides or analogies for constructing psychological and social models that attempt to resolve the conflicts.

‗‗‗‗‗‗‗. The Survival of the Wisest. New York: Harper & Row, 1973. Salk greatly extends his concept of dualisms and introduces the idea of metabiology, a philosophic extension of the life sciences. From this perspective, Salk argues that resolution of conflicts arising from dualisms is not only possible but also necessary.

Salk, Jonas, and Jonathan Salk. World Population and Human Values: New Reality. New York: Harper & Row, 1981. The ideas of Salk’s metabiology are applied to the problem of overpopulation. Each concept is accompanied by a separate diagram. Provides a global perspective by using United Nations vital statistics and population trends in different continents and cultures.