SV40 stands for Simian Virus 40.
SV40 was the 40th virus found in rhesus monkey kidney cells when these cells were used to make the polio vaccine. This virus contaminated both the Inactivated Polio Vaccine (IPV) created by Dr. Jonas Salk and the Oral or "Live" Polio Vaccine (OPV) created by Dr. Albert Sabin.
Children being fed sugar cubes with the oral polio vaccine. Circa 1961.
In 1961, SV40 was discovered by Dr. Bernice Eddy of the National Institute of Health, Division of Biologics when she took the material used to grow polio vaccines and injected it into hamsters. Tumors grew in the hamsters. Her discovery was subsequently validated by Drs. Maurice Hilliman and Benjamin Sweet of Merck.
Upon the discovery that SV40 was an animal carcinogen that had found its way into the polio vaccines, a new federal law was passed in 1961 that required that no vaccines contain this virus. However, this law did not require that SV40 contaminated vaccines be thrown away or that the contaminated seed material (used to make all polio vaccines for the next four decades) be discarded. As a result, known SV40 contaminated vaccines were injected into children up until 1963. In addition, it has been alleged that there have been SV40-contaminated batches of oral polio vaccine administered to some children until the end of the 1990's.
The Creation of the Oral Polio Vaccine
Type I has the following lineage:
• In 1941, Drs. Francis and Mack isolated the Mahoney poliovirus “from the pooled feces of three healthy children in Cleveland.” Dr. Salk then subjected the strain to passages through fourteen living monkeys and two cultures of monkey testicular cultures.
• In 1954, the strain (now called Monk14 T2) was given to Drs. Li and Schaeffer who subjected the virus to nine more passages through monkey testicular cultures.
• Next, the strain (now called Monk14 T11) underwent fifteen more passages in monkey testicular cultures, eighteen passages in monkey kidney cells, two passages through the skin of living rhesus monkeys, and additional passages through African Green monkey skin and monkey kidney cell cultures. This strain was now called MS10 T43 or LS-c.
• In 1956, Dr. Sabin took this virus and passaged it through seven cultures of African Green Monkey kidney cells.
• That same year, the pharmaceutical company, Merck, Sharp & Dohme, passed the strain (now called LS-c, 2ab/KP2) through a rhesus monkey kidney cell culture.
• The resulting material was called Sabin Original Merck (SOM) and was provided to Lederle in 1960 as the seed material to manufacture its polio vaccine.
Types II and III were created in a similar fashion.
-- A.B. Sabin, A.B. & L. Boulger, History of Sabin Attenuated Poliovirus Oral Live Vaccine Strains. 1 J. BIOL. STAND. 115, 11518 (1973).