Evaluation of a Novel Multiplex Human Papillomavirus (HPV) Genotyping Assay for HPV Types in Skin Warts

Human papillomaviruses (HPV) of the genera alpha, mu, and nu induce benign tumors of the cutaneous epithelia that constitute a significant burden for immunocompromised adults. Currently, no gold standard for genotyping of these HPV types exists. In this study, we describe the prevalence of genus alpha, mu, and nu HPV types in cutaneous warts. We developed a novel multiplex HPV genotyping assay, BSwart-PCR/MPG (BSwart), to type sensitively and specifically 19 cutaneous HPV types frequently found in warts. BSwart-PCR/MPG is based on a multiplex PCR using broad-spectrum primers and subsequent multiplex hybridization to type-specific probes coupled to Luminex beads. In a first application comprising 100 cutaneous warts, the assay was compared to another, recently described genotyping assay, the HSL-PCR/MPG. When a 10-fold dilution series was used, the detection limit was between 10 and 100 HPV genomes per PCR. When comparing the two assays, there was an excellent agreement in detecting dominant HPV types; however, we also obtained evidence for a higher sensitivity of the BSwart assay for multiple infections in these cutaneous warts. Using BSwart, HPV was found in 95% of wart preparations, with HPV1 being most prevalent, followed by types 27, 57, and 2. Both novel BSwart and HSL-PCR/MPG HPV genotyping assays are powerful high-throughput tools that could be used to learn more about the natural history of cutaneous HPV. They would be advantageous to monitor the efficacy of future skin HPV vaccines and to identify novel HPV vaccine candidates.