Looking back over the two discoveries rewarded with the 2008 Nobel Prize in Physiology or Medicine reveals two different timelines for discovery research. One, Harald zur Hausen’s realization that subtypes of a virus that produces harmless warts can also lead to cervical cancer, took a decade of work to prove, initially against a backdrop of considerable skepticism. The other, Françoise Barré-Sinoussi and Luc Montagnier’s identification of the virus associated with AIDS, occurred within just a few months amid a flurry of global research activity directed to finding the cause of the then-new epidemic.

Harald zur Hausen’s suggestion that human papilloma virus (HPV) infection might lie behind cervical cancer flew in the face of general opinion in the early 1970s, which held that another commonly present virus, herpes simplex virus, might be the cause. Realizing that there were a multitude of different HPV subtypes, and hypothesizing that unknown subtypes might cause the cancer, zur Hausen’s group began a painstaking search for such novel viruses. By the early 1980s they found novel viruses in genital warts. Their subsequent identification of two novel HPV subtypes in cervical cancers formed the essential piece of evidence linking HPV infection to the onset of the disease.

Françoise Barré-Sinoussi and Luc Montagnier’s discovery of the virus that later came to be known as human immunodeficiency virus (HIV) occurred just two years after the first reports of cases of what we now know as AIDS. An infective agent was suspected by many to cause the disease, and they decided to test whether it might be a so-called retrovirus. Retroviruses are relatively uncommon among the viruses that infect humans and rely on the host’s cellular machinery to make their viral DNA. The gamble proved correct; their studies revealed retroviral activity in cells taken from a patient’s lymph nodes, and demonstrated that virus from these cells could infect and kill white blood cells. Within the year, Barré-Sinoussi and Montagnier had isolated HIV from several patient groups.