Genetic diversity of HPV-6 in concurrent multiple anogenital warts.

INTRODUCTION

Anogenital warts (AGW) are the most common benign tumors in the anogenital area. They are etiologically associated with alpha human papillomaviruses (HPV), in more than 90% of cases with HPV-6 and HPV-11. AGW frequently displays a multifocal and multicentric appearance. However, it is not clear whether the occurrence of multiple AGW in a particular patient is a consequence of infection with single or multiple HPV genomic variants of a given HPV genotype.

METHODS

Forty-five HPV-6 isolates from fresh-frozen AGW tissue specimens, obtained from 18 patients with concurrent multiple AGW, were included. The entire HPV-6 L1, E5a, E5b ORFs, and LCR genomic region was sequenced.

RESULTS

Fourteen different HPV-6 L1-LCR-E5a-E5b genomic variants were identified among 18 patients with concurrent multiple AGW. In 17 out of 18 patients, a single identical HPV-6 L1-E5a-E5b-LCR genomic variant was identified in all concurrent multiple AGW collected in an individual patient. Co-infection with two different HPV-6 genomic variants was identified in one patient.

DISCUSSION: The presence of an identical HPV genomic variant in all concurrently present multiple AGW within an individual patient supports the hypothesis that the occurrence of multiple concurrent AGW is a consequence of infection with a single HPV-6 genomic variant, rather than infection with multiple genomic variants of HPV-6.