 In 1949, John F. Enders (1897–1985) Thomas Weller (1915–2008), and Frederick Robbins (1916–2003) grew polio virus for the first time in cultured human embryo cells, the first virus to be grown without using solid animal tissue or eggs.Infections by poliovirus most often cause the mildest of symptoms.This was not known until the virus was isolated in cultured cells and many people were shown to have had mild infections that did not lead to poliomyelitis.