One Virus is One Too Many!

Contributed by Teknika Tucker, Class of 2019

Max Theiler was a virologist who contributed to vaccine development for yellow fever.  Theiler was born in Pretoria, South African and was influenced by his father, a veterinary bacteriologist, to pursue a career in medicine. Theiler received his formal education in Cape Town, South Africa and eventually enrolled in a pre-medical program at the University of Cape Town.

Theiler continued his education at the London School of Tropical medicine and became a Licentiate of the Royal College of Physicians of London and a member of the Royal College of Surgeons of England.

Due to Theiler’s desire to pursue a career in research, he accepted a position as assistant at the Harvard University School of Tropical Medicine in Cambridge, Massachusetts.  This position allowed Theiler to began further research on yellow fever.

Yellow fever is a virus found in tropical and subtropical areas in South America and Africa.  Illnesses range in severity from a self-limited febrile illness to severe liver disease with bleeding.  Yellow fever is diagnosed based on symptoms, physical findings, laboratory testing, and travel history, including the possibility of exposure to infected mosquitoes.

theilerTheiler remained at Harvard until 1930 and along with his colleagues was able to prove that yellow fever was not caused by bacterium and instead was a virus.   Previous research discovered that the Rhesus monkey could contract yellow fever and be used for experimentation. However, Theiler discovered that using mice provided more research advantages.  Since Theiler’s discovery mice have been the standard for research using animals.

In 1930, he continued his research at The Rockefeller Institute center for virus research where he later became director of the Virus Laboratory.  At the Rockefeller Institute he was able to determine that passing the virus from mouse to mouse decreased the incubation period and increase the fatality of the disease.  This allowed Theiler and his colleagues to develop what is known today as attenuated live vaccine from their research data.  Arriving at an attenuated live vaccine allowed the virus to be too weak to cause harm but capable of generating a response of immunity.  Theiler also developed the “mouse protection test” which was used to gauge the amount of immunity to yellow fever.  He used different strains of yellow fever in many different tissue cultures, including chicken embryos, to verify its ability to invade the nervous system.  Removing this ability would make the vaccine safe.

Theiler and his colleagues tested many cultures and the Asibi strain proved to be harmless making it effective to produce vaccine.   This strain led to the development of 17D strain.   17D was then mass-produced by the Rockefeller Foundation and was so successful that yellow fever was no longer considered a major disease.

Max Theiler is a major contributor to vaccine development.  In his work he used mice, which proved to be a benefit and advantage for the research community that is still in tact today.  He continued to research origins of many other disorders and discovered a disease that carries his name, Theiler’s disease.  Theiler success has been honored numerous times for his advancement of vaccine development.


  1. His, By 1927 He and. “Max Theiler – Biographical.” Max Theiler – Biographical. N.p., n.d. Web. 24 Sept. 2016.<;.
  1. By 1930, the Year That Max Theiler (1899-1972) Arrived at the. “Hospital ” The Rockefeller University ». N.p., n.d. Web. 26 Sept. 2016. <;.
  1. Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 12 July 2016. Web. 26 Sept. 2016. <;.


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