The hypothesis that cancer of the cervix is infectious was raised more than 150 years ago (Rigoni-Stern 1842). The first cell-free transmissions of papillomas were reported 95 years ago (McFadyan and Hobday 1898). A report of cell- free trans-mission of human warts was published in 1907 (Ciuffo). Thus, since these initial discoveries papillomavirus research has had to go a long way before it became possible to link these infections to cancer of the cervix (Durst et al. 1983; Boshart et al. 1984). Table 1 lists a selection of the publications that form the basis for our present understand- ing of the role of human pathogenic papillomaviruses (H PV) in human cancers. The identification of specific H PV types in cervical cancer in 1983, 1984 and in subsequent years substantially boosted activities in papillomavirus research. In part this is because cancer of the cervix ranks first in cancer incidence in develop- ing countries and is an important cause of cancer death in affluent societies (Parkin etal. 1984; I.A.R.C. 1989). Premalignant cervical lesions, particularly in affluent soci- eties, also contribute considerably to morbidity.
Moreover, the availability of cell lines harboring H PV DNA and the identification of H PV genes as oncogenes have permitted in vitro analyses of H PV genome persistence, gene expression, and gene functions.