Jonas Edward Salk
Salk, Jonas (1914-1995)
Salk, Jonas (1914-1995)
Jonas Salk was one of the United States's best-known microbiologists, chiefly celebrated for his discovery of his polio vaccine . Salk's greatest contribution to immunology was the insight that a "killed virus" is capable of serving as an antigen , prompting the body's immune system to produce antibodies that will attack invading organisms. This realization enabled Salk to develop a polio vaccine composed of killed polio viruses , producing the necessary antibodies to help the body to ward off the disease without itself inducing polio.
The eldest son of Orthodox Jewish-Polish immigrants, Jonas Edward Salk was born in East Harlem, New York, on October 28, 1914. His father, Daniel B. Salk, was a garment worker, who designed lace collars and cuffs and enjoyed sketching in his spare time. He and his wife, Dora Press, encouraged their son's academic talents, sending him to Townsend Harris High School for the gifted. There, young Salk was both highly motivated and high achieving, graduating at the age of fifteen and enrolling in the legal faculty of the City College of New York. Ever curious, he attended some science courses and quickly decided to switch fields. Salk graduated with a bachelor's degree in science in 1933, at the age of nineteen, and went on to New York University's School of Medicine. Initially he scraped by on money his parents had borrowed for him; after the first year, however, scholarships and fellowships paid his way. In his senior year, Salk met the man with whom he would collaborate on some of the most important work of his career, Dr. Thomas Francis, Jr.
On June 7, 1939, Salk was awarded his M.D. The next day, he married Donna Lindsay, a psychology major who was employed as a social worker. The couple eventually had three sons. After graduation, Salk continued working with Francis, and concurrently began a two-year internship at Mount Sinai Hospital in New York. Upon completing his internship, Salk accepted a National Research Council fellowship and moved to The University of Michigan to join Dr. Francis, who had been heading up Michigan's department of epidemiology since the previous year. Working on behalf of the U.S. Army, the team strove to develop a flu vaccine. Their goal was a "killed-virus" vaccine—able to kill the live flu viruses in the body, while simultaneously producing antibodies that could fight off future invaders of the same type, thus producing immunity . By 1943, Salk and Francis had developed a formalin-killed-virus vaccine, effective against both type A and B influenza viruses, and were in a position to begin clinical trials.
In 1946, Salk was appointed assistant professor of epidemiology at Michigan. Around this time he extended his research to cover not only viruses and the body's reaction to them, but also their epidemic effects in populations. The following year he accepted an invitation to move to the University of Pittsburgh School of Medicine's Virus Research Laboratory as an associate research professor of bacteriology. When Salk arrived at the Pittsburgh laboratory, what he encountered was not encouraging. The laboratory had no experience with the kind of basic research he was accustomed to, and it took considerable effort on his part to bring the lab up to par. However, Salk was not shy about seeking financial support for the laboratory from outside benefactors, and soon his laboratory represented the cutting edge of viral research.
In addition to building a respectable laboratory, Salk also devoted a considerable amount of his energies to writing scientific papers on a number of topics, including the polio virus. Some of these came to the attention of Daniel Basil O'Connor, the director of the National Foundation for Infantile Paralysis—an organization that had long been involved with the treatment and rehabilitation of polio victims. O'Connor eyed Salk as a possible recruit for the polio vaccine research his organization sponsored. When the two finally met, O'Connor was much taken by Salk—so much so, in fact, that he put almost all of the National Foundation's money behind Salk's vaccine research efforts.
Poliomyelitis , traceable back to ancient Egypt, causes permanent paralysis in those it strikes, or chronic shortness of breath often leading to death. Children, in particular, are especially vulnerable to the polio virus. The University of Pittsburgh was one of four universities engaged in trying to sort and classify the more than one hundred known varieties of polio virus. By 1951, Salk was able to assert with certainty that all polio viruses fell into one of three types, each having various strains; some of these were highly infectious, others barely so. Once he had established this, Salk was in a position to start work on developing a vaccine.
Salk's first challenge was to obtain enough of the virus to be able to develop a vaccine in doses large enough to have an impact; this was particularly difficult since viruses, unlike culture-grown bacteria , need living cells to grow. The breakthrough came when the team of John F. Enders , Thomas Weller , and Frederick Robbins found that the polio virus could be grown in embryonic tissue—a discovery that earned them a Nobel Prize in 1954.
Salk subsequently grew samples of all three varieties of polio virus in cultures of monkey kidney tissue, then killed the virus with formaldehyde. Salk believed that it was essential to use a killed polio virus (rather than a live virus) in the vaccine, as the live-virus vaccine would have a much higher chance of accidentally inducing polio in inoculated children. He therefore, exposed the viruses to formaldehyde for nearly 13 days. Though after only three days he could detect no virulence in the sample, Salk wanted to establish a wide safety margin; after an additional ten days of exposure to the formaldehyde, he reasoned that there was only a one-in-a-trillion chance of there being a live virus particle in a single dose of his vaccine. Salk tested it on monkeys with positive results before proceeding to human clinical trials.
Despite Salk's confidence, many of his colleagues were skeptical, believing that a killed-virus vaccine could not possibly be effective. His dubious standing was further compounded by the fact that he was relatively new to polio vaccine research; some of his chief competitors in the race to develop the vaccine—most notably Albert Sabin , the chief proponent for a live-virus vaccine—had been at it for years.
As the field narrowed, the division between the killed-virus and the live-virus camps widened, and what had once been a polite difference of opinion became a serious ideological conflict. Salk and his chief backer, the National Foundation for Infantile Paralysis, were lonely in their corner. Salk failed to let his position in the scientific wilderness dissuade him and he continued, undeterred, with his research. To test his vaccine's strength, in early 1952, Salk administered a type I vaccine to children who had already been infected with the polio virus. Afterwards, he measured their antibody levels. His results clearly indicated that the vaccine produced large amounts of antibodies. Buoyed by this success, the clinical trial was then extended to include children who had never had polio.
In May 1952, Salk initiated preparations for a massive field trial in which over four hundred thousand children would be vaccinated. The largest medical experiment that had ever been carried out in the United States, the test finally got underway in April 1954, under the direction of Dr. Francis and sponsored by the National Foundation for Infantile Paralysis. More than one million children between the ages of six and nine took part in the trial, each receiving a button that proclaimed them a "Polio Pioneer." A third of the children were given doses of the vaccine consisting of three injections—one for each of the types of polio virus—plus a booster shot. A control group of the same number of children was given a placebo, and a third group was given nothing.
At the beginning of 1953, while the trial was still at an early stage, Salk's encouraging results were made public in the Journal of the American Medical Association. Predictably, media and public interest were intense. Anxious to avoid sensationalized versions of his work, Salk agreed to comment on the results thus far during a scheduled radio and press appearance.
Despite the doomsayers, on April 12, 1955, the vaccine was officially pronounced effective, potent, and safe in almost 90% of cases. The meeting at which the announcement was made was attended by five hundred of the world's top scientists and doctors, 150 journalists, and sixteen television and movie crews. The success of the trial catapulted Salk to instant stardom.
Wishing to escape from the glare of the limelight, Salk turned down the countless offers and tried to retreat into his laboratory. Unfortunately, a tragic mishap served to keep the attention of the world's media focused on him. Just two weeks after the announcement of the vaccine's discovery, eleven of the children who had received it developed polio; more cases soon followed. Altogether, about 200 children developed paralytic polio, eleven fatally. For a while, it appeared that the vaccination campaign would be railroaded. However, it was soon discovered that all of the rogue vaccines had originated from the same source, Cutter Laboratories in California. On May 7, the vaccination campaign was called to a halt by the Surgeon General. Following a thorough investigation, it was found that Cutter had used faulty batches of virus culture , which were resistant to the formaldehyde. After furious debate and the adoption of standards that would prevent such a reoccurrence, the inoculation resumed. By the end of 1955, seven million children had received their shots, and over the course of the next two years more than 200 million doses of Salk's polio vaccine were administered, without a single instance of vaccine-induced paralysis. By the summer of 1961, there had been a 96% reduction in the number of cases of polio in the United States, compared to the five-year period prior to the vaccination campaign.
After the initial inoculation period ended in 1958, Salk's killed-virus vaccine was replaced by a live-virus vaccine developed by Sabin; use of this new vaccine was advantageous because it could be administered orally rather than intravenously, and because it required fewer "booster" inoculations. To this day, though, Salk remains known as the man who defeated polio.
In 1954, Salk took up a new position as professor of preventative medicine at Pittsburgh, and in 1957 he became professor of experimental medicine. The following year he began work on a vaccine to immunize against all viral diseases of the central nervous system. As part of this research, Salk performed studies of normal and malignant cells, studies that had some bearing on the problems encountered in cancer research. In 1960, he founded the Salk Institute for Biological Studies in La Jolla, California; heavily funded by the National Foundation for Infantile Paralysis (by then known as the March of Dimes), the institute attracted some of the brightest scientists in the world, all drawn by Salk's promise of full-time, uninterrupted biological research.
Salk died on 23 June 1995, at a San Diego area hospital. His death, at the age of 80, was caused by heart failure.
See also Antibody and antigen; Antibody formation and kinetics; Immunity, active, passive and delayed; Immunization; Poliomyelitis and polio
The American physician, virologist (scientist who studies viruses), and immunologist (medical scientist concerned with the structure and function of the immune system, the body's resistance to infection) Jonas Salk developed the first effective poliomyelitis (polio) vaccine.
Early years and education
Jonas Edward Salk was born in New York City on October 28, 1914, the oldest of three sons of Daniel and Dora Salk. The family moved to the Bronx, New York, shortly after Jonas's birth. As a child he was thin and small and did not do well at sports, although he was an excellent student. With his mother's encouragement, he had a sense as a child that when he grew up he would "make a difference" by doing something significant.
Salk graduated from Townsend Harris High School, a school for exceptional students. He studied hard, read everything he could lay his hands on, and always got good grades. At the age of sixteen Salk entered the College of the City of New York to study law. He subsequently changed his mind and decided instead to pursue medicine. In 1934 he enrolled in the College of Medicine of New York University, from which he graduated in 1939. Salk worked at New York's Mount Sinai Hospital from 1940 to 1942, when he went to the University of Michigan. There he helped develop an influenza (flu) vaccine. In 1944 he was appointed research associate in epidemiology (the study of the causes, distribution, and control of disease), and in 1946 he was made assistant professor.
In 1947 Salk accepted a position at the University of Pittsburgh as associate professor of bacteriology (the study of bacteria, one-celled organisms that can cause disease). There he carried out his research on a polio vaccine. Polio vaccines had been attempted before but without success. Until 1949 it was not known that there were three distinct types of polio viruses.
This discovery provided a starting point for Salk. Working under a grant from the National Foundation for Infantile Paralysis, he prepared a killed-virus vaccine effective against all three types. Testing began in 1950, and the preliminary report on the vaccine's effectiveness was published in the Journal of the American Medical Association in 1953. National field trials were held in 1954, and in 1955 the vaccine was determined safe for general use.
The Salk vaccine is made by cultivating (growing) three strains of the virus separately, then killing it by applying a strong chemical called formaldehyde. Tests are then performed to make certain the virus is dead. A series of three or four injections is required to make someone immune.
Problems with the Salk vaccine
Acceptance of the vaccine was not without problems. Salk was criticized because a glaring Hollywood-like promotion was undertaken for the vaccine. Also, some medical colleagues favored a live-virus vaccine. The live-virus vaccine developed by Dr. Albert Sabin (1906–1993) contained a mutant (altered, different) form of the polio virus, called an avirulent virus. This means it was not able to harm the body's defenses. The live-virus vaccine had advantages over the killed-virus vaccine. It could be administered orally (through the mouth) rather than by injection, and one dosage gave permanent immunity.
The biggest problem with the Salk vaccine was that improper production of the vaccine by some drug companies resulted in the vaccine being contaminated with live polio virus. Many hundreds of children died or became extremely ill because of this.
Salk, during his polio researches, was made research professor of bacteriology at Pittsburgh, Pennsylvania, (1949–1954) and professor of preventive medicine (1954–1957). In 1957 he was named Commonwealth professor of experimental medicine.
In 1963 he opened the Salk Institute for Biological Studies in San Diego, California. There he and his colleagues studied problems relating to the body's autoimmunization reaction; that is, why the body rejects foreign material, for example, an organ transplant.
Jonas Salk died on June 23, 1995, in La Jolla, California, at the age of eighty from heart failure. In his lifetime he was able to see the effects of his life's work. By the time Salk died, polio had virtually disappeared from the United States.
For More Information
Barter, James. Jonas Salk. San Diego: Lucent, Gale, 2002.
Carter, Richard. Breakthrough: The Saga of Jonas Salk. New York: Trident Press, 1966.
Curson, Marjorie. Jonas Salk. Englewood Cliffs, NJ: Silver Burdett, 1990.
McPherson, Stephanie Sammartino. Jonas Salk: Conquering Polio. Minneapolis: Lerner, 2002.
Naden, Corinne J., and Rose Blue. Jonas Salk: Polio Pioneer. Brookfield, CT: Millbrook Press, 2001.
Tocci, Salvatore. Jonas Salk: Creator of the Polio Vaccine. Berkeley Heights, NJ : Enslow, 2002.
Jonas Edward Salk
Jonas Edward Salk
American Virologist and Physician
Jonas Salk is best known for his pioneering research on poliomyelitis ("infantile paralysis") and his development of an injectable killed virus vaccine for prevention of the disease. Wide scale testing in 1954 quickly led to the national distribution of the Salk vaccine. Immunization campaigns resulted in a major reduction in the incidence of poliomyelitis in the United States. Work by Salk's rival, Albert Sabin (1906-1993), led to the development of a live attenuated vaccine that could be administered orally.
Salk was born in New York City. He was the oldest son of Russian-Jewish immigrants who encouraged their children to pursue higher educational and professional goals. Salk attended Townsend Harris High School and the City College of New York. His original intention was to study law, but he was attracted to the medical sciences and decided to become a doctor. While a student at the medical school of New York University, Salk began research on the recently discovered influenza virus. This work served as the basis for his later research on the poliovirus and convinced him that he would prefer research to medical practice. He received his medical degree in 1939 and began a two-year internship at Mount Sinai Hospital, New York. He applied to Dr. Thomas Francis, Jr., a respected virologist and epidemiologist, for a research position in his laboratory at the University of Ann Arbor, Michigan. During World War II, Salk worked with Francis on influenza, a problem that was considered significant to the war effort. Salk moved to Ann Arbor in 1942 and spent the next six years working on various was of inactivating the influenza virus and producing a safe and effective vaccine. In 1947 Salk accepted an offer from the University of Pittsburgh Medical School, where he became the only full-time member of the medical school faculty. The Sarah Mellon Scaife Foundation provided funds for renovation of Salk's laboratory. To secure funds for research, Salk applied to the National Foundation for Infantile Paralysis and began research on the poliovirus. The next eight years were devoted to the development of a vaccine against polio.
During the 1950s, poliomyelitis was one of the most feared epidemic childhood diseases, because infection could lead to paralysis or even death. Poliomyelitis is an acute viral infection that can invade the nervous system, but where the disease is common, most infections probably go unnoticed, or result in a mild febrile illness, with sore throat, headache, vomiting, and stiffness of the neck and back. Before the introduction of the polio vaccine, the annual incidence in the United States during certain epidemic years reached over 10,000 paralytic cases. Such epidemics formed the basis of the image of polio as the great crippler of children, and exerted a profound influence on the direction of medical research.
Although the natural history of poliomyelitis was still generally obscure, Albert Sabin had proved that the virus was spread by the fecal-oral route rather than the nasal route. Before Sabin had perfected his oral vaccine, Salk developed a successful killed vaccine that was administered by injection. A nationwide trial of the Salk vaccine in 1954 was successful. The results of the trial were announced in April 1955 and led to widespread acclaim for Salk, who was further lauded for his refusal to patent the vaccine. As a result of the Salk vaccine program, and the efforts of the National Foundation for Infantile Paralysis, the incidence of paralytic polio in the United States decreased dramatically by 1961. In 1963 Salk established the Jonas Salk Institute for Biological Studies in La Jolla, California, to encourage innovative scientific and medical research. During the last years of his life, Salk remained active in research dealing with AIDS.
LOIS N. MAGNER
Jonas Edward Salk
Jonas Edward Salk
The American physician, virologist, and immunologist Jonas Edward Salk (born 1914) developed the first effective poliomyelitis (polio) vaccine.
Jonas Salk was born in New York City on Oct. 28, 1914. At the age of 16 he entered the College of the City of New York with the thought of studying law. He decided instead to study medicine and in 1934 enrolled in the College of Medicine of New York University, from which he graduated in 1939. He interned at New York's Mount Sinai Hospital from 1940 to 1942, when he went to the University of Michigan, where he helped develop an influenza vaccine. In 1944 he was appointed research associate in epidemiology, and in 1946 he was made assistant professor.
In 1947 Salk accepted a position at the University of Pittsburgh as associate professor of bacteriology, where he carried out his researches on a polio vaccine. Polio vaccines had been attempted before but without success because, as was apparent by 1949, there were three distinct types of polio viruses. This provided a starting point for Salk, who, working under a grant from the National Foundation for Infantile Paralysis, prepared a killed-virus vaccine effective against all three types. Testing began in 1950, and the preliminary report on the vaccine's effectiveness was published in the Journal of the American Medical Association for 1953. National field trials were held in 1954, and in 1955 the vaccine was determined safe for general use.
Acceptance of the vaccine was not without problems for Salk. Fear, skepticism, opposition from medical colleagues who favored a live-virus vaccine, improper production of the vaccine by some pharmaceutical companies, and a glaring Hollywood-like promotion for the vaccine caused much scientific criticism of Salk. Many also felt that the National Foundation had improperly favored him. Although the Salk vaccine was effective, it was replaced largely by the Sabin oral vaccine, a live-virus vaccine which, unlike the Salk vaccine, provides permanent protection.
During his polio researches Salk was made research professor of bacteriology at Pittsburgh (1949-1954) and professor of preventive medicine (1954-1957). In 1957 he was named Commonwealth professor of experimental medicine. In 1963 he opened the Salk Institute for Biological Studies in San Diego, where he and his colleagues studied problems relating to the body's autoimmunization reaction; that is, why the body rejects foreign material, for example, an organ transplant.
Jonas Salk died in June 1995 at the age of 80 from heart failure. In his lifetime he was able to see the effects of his life's work. By the time Salk died, polio had been virtually disappeared from the United States.
Richard Carter, Breakthrough: The Saga of Jonas Salk (1966), details the development of the vaccine and emphasizes Salk's dedication to humanity. A harsher view of Salk's role in developing the vaccine is John R. Wilson, Margin of Safety (1963). Several books contain well-balanced sections on Salk, such as Greer Williams, Virus Hunters (1959), and H. J. Parish, A History of Immunization (1965). Information regarding Salk's life and death can be found by reading "The Good Doctor," Time (July 3, 1995) and " When the Vaccine Causes The Polio," Time (October 30, 1995). □