Hausen and colleagues showed for the first time that a cancer virus (Epstein-Barr virus) can transform healthy cells (lymphocytes) into cancer cells. This showed that viruses can cause cancer cell formation. (Order of authorship in the original publication: W. Henle, Diehl, Kohn, zur Hausen, G. Henle.)

In 2008 Harold zur Hausen received half of the Nobel Prize in Physiology or Medicine 2008  "for his discovery of human papilloma viruses causing cervical cancer." The other half was awarded jointly to Françoise Barré-Sinoussi and Luc Montagnier "for their discovery of human immunodeficiency virus."