Characterization of a New Type of Human Papillomavirus That Causes Skin Warts

Abstract

A human papillomavirus (HPV) was isolated from the lesions of a patient (ML) bearing numerous hand common warts. This virus was compared with the well-characterized HPV found in typical plantar warts (plantar HPV). ML and plantar HPV DNA have similar MW (5.26 .times. 106 and 5.23 .times. 106, respectively) but were shown to be different by restriction enzyme analysis. When the cleavage products of both DNA by endonuclease EcoRI, BamI, HpaI or Hind were analyzed by EM, 1, 2, 1 and 4 fragments were detected for ML HPV DNA instead of the 2, 1, 2 and 6 fragments, respectively, detected for plantar HPV DNA. Unlike plantar HPV DNA, a high proportion of ML HPV DNA molecules were resistant to these restriction enzymes. Most, if not all, of the molecules were resistant to BamI and sensitive to EcoRI or sensitive to BamI and resistant to EcoRI. After denaturation and renaturation of the cleavage products of ML HPV DNA by a mixture of the 2 enzymes, the circular heteroduplexes formed showed 1-3 heterology loops corresponding to about 4-8% of the genome length. No sequence homology was detected between ML and plantar HPV DNA by c[complementary]RNA-DNA filter hybridization, by measuring the reassociation kinetics of an iodinated plantar HPV DNA in the presence of a 25-fold excess of ML HPV DNA or by the heteroduplex technique. The 2 viruses had distinct electrophoretic polypeptide patterns and showed no antigenic cross-reaction by immunodiffusion or immunofluorescence techniques. Preliminary cRNA-DNA hybridization experiments, using viral DNA from single or pooled plantar or hand warts, suggest that hand common warts are associated with viruses similar or related to ML HPV. The existence of at least 2 distinct types of HPV that cause skin warts was demonstrated, they were provisionally called HPV type 1 and HPV type 2, with plantar HPV and ML HPV as prototypical viruses, respectively.