Double infection with human papillomavirus 1 and human papillomavirus 63 in single cells of a lesion displaying only an human papillomavirus 63-induced cytopathogenic effect.

BACKGROUND

Specific histologic features are associated with the presence of certain human papillomaviruses (HPV) in verrucous lesions of the skin. HPV 1 is known to be associated with eosinophilic keratohyalin-like intracytoplasmic inclusion bodies, granular in appearance, whereas the recently described HPV 63 seems to induce inclusion bodies displaying a filamentous structure. Although an infection by two distinct HPV types within a single cell has not been previously reported, we have recently treated a plantar punctate keratotic wart in which only the histologic features seen in an HPV 63-induced lesion were seen, in spite of the detection of double infection of both HPV 1 and HPV 63 DNAs, thus posing the question as to the role of the HPV 1 present in the lesion.

EXPERIMENTAL DESIGN

To localize the genomes of these two viruses within the lesion, double fluorescence in situ hybridization was performed using biotin-labeled HPV 63 DNA and digoxigenin-labeled HPV 1 DNA. The distribution of the genomes of these two viruses was examined in comparison with the histologic features in the lesion. The copy numbers of HPV 63 and HPV 1 were compared on agarose gel electrophoresis, stained with ethidium-bromide.

RESULTS

We demonstrated the presence of the DNA of both HPV 1 and HPV 63 within the same nucleus of a plantar wart. In spite of the double infection of these two viruses in a cell and more or less equal copy numbers of the viruses, the cytopathogenic effect of only HPV 63 was seen in the cells.

CONCLUSIONS

This is the first report of double infection of two different types of HPV within the same nucleus. Our findings suggest the possible interference that two HPV types could have on each other in inducing the HPV type specific cytopathogenic effects.