Zur Hausen and colleagues discovered HPV18 as a cause of cervical cancer. With the discovery of HPV18, and HPV16, which zur Hausen and team discovered in 1983, zur Hausen discovered the viruses causing about 75% of human cervical cancer, and provided a basis on which other researchers could develop a vaccine against cervical cancer. (Order of authorship in the original publication: Boshart, Gissmann, Ikenberg, Kleinheinz, Scheurlen, zur Hausen.)  Digital facsimile from PubMedCentral at this link.

"Harald zur Hausen went against current dogma and postulated that oncogenic human papilloma virus (HPV) caused cervical cancer.^[25] He realized that HPV-DNA could exist in a non-productive state in the tumours, and should be detectable by specific searches for viral DNA.^[77] He and others, notably workers at the Pasteur Institute, found HPV to be a heterogeneous family of viruses. Only some HPV types cause cancer.^[25]

"Harald zur Hausen pursued his idea of HPV for over 10 years by searching for different HPV types. [3] This research was difficult due to the fact that only parts of the viral DNA were integrated into the host genome. He found novel HPV-DNA in cervix cancer biopsies, and thus discovered the new, tumourigenic HPV16 type in 1983. In 1984, he cloned HPV16 and 18 from patients with cervical cancer.^[77] The HPV types 16 and 18 were consistently found in about 70% of cervical cancer biopsies throughout the world.^[25]

"His observation of HPV oncogenic potential in human malignancy provided impetus within the research community to characterize the natural history of HPV infection, and to develop a better understanding of mechanisms of HPV-induced carcinogenesis.^{[25] (Wikipedia article HPV vaccine, accessed 5-2020).}