[New developments relating to papillomaviruses].

Molecular hybridization technique and immunofluorescence studies with use of specific immune sera against the purified virions isolated from various types of warts and wart-like lesions of epidermodysplasia verruciformis (EV) made it possible to detect four different types of human papilloma viruses (HPV). The recognition of the viruses is important because of the different morphology of the lesions induced and their various oncogenic potentials. HPV1 is mainly responsible for plantar warts, HPV2 for common (hand) warts, HPV3 has been found both in flat warts and in the variety of EV in which skin lesions are of flat wart type, the course is relatively more benign, and usually malignant transformation is not to be expected. HPV4 was up to now found exclusively in the cases of EV with prevalent red and red-brownish plaques and hyper- and depigmentations similar to those of pityriasis versicolor. In all cases of this variety of EV malignancies occured invariably. In patients with EV, as also in--to a lesser extent--longstanding flat and/or common warts cell mediated immunity was in general lowered, but humoral specific anti-HPV antibodies were usually present. HPV type seems to be of a decisive significance for potential oncogenesis, because in a vast majority of cases EV due to HPV3 no malignancies occured in spite of anergy, whereas malignant transformation has been found in all cases due to HPV4, even in a patient with still preserved, although lowered, CMI.