Harald zur Hausen, a German researcher who suspected, and later helped to prove that genital HPV infection can lead to cervical cancer, was awarded half of the $1.4 million Nobel Prize in Medicine in 2007 for his work. Verification that cervical cancer is caused by an infectious agent led several other groups to develop vaccines against HPV strains that cause most cases of cervical cancer. The other half of the award went to Françoise Barré-Sinoussi and Luc Montagnier, two French virologists, for their part in the discovery of HIV.