Abundance of Multiple High-Risk Human Papillomavirus (HPV) Infections Found in Cervical Cells Analyzed by Use of an Ultrasensitive HPV Genotyping Assay

PCR methods enable the detection of a large variety of human papillomavirus (HPV) genotypes that infect the anogenital tract. However, PCR with consensus primers, general primers, and, to a lesser extent, broad-spectrum primers may underrepresent the true prevalence of HPV, especially the true prevalence of multiple infections. We compared the rate of HPV positivity determined by a broad-spectrum PCR with primers BSGP5+ and BSGP6+ (BS-PCR) coupled to an established bead-based multiplex HPV genotyping (MPG) assay with the rate of HPV positivity determined by a multiplex PCR with type-specific primers (TS-PCR) coupled to a newly developed MPG assay for 735 selected cervical scraping samples. While the primers used for the BS-PCR are located within the L1 region of the HPV genome, the primers used for the TS-PCR target the E7 gene. The overall rates of positivity for the 19 HPV types included in both assays were 60.9% and 72.2% by the BS-PCR and the TS-PCR, respectively, and the two assays found multiple infections in 34.8% and 58.0% of the specimens, respectively. Both HPV detection assays allowed the semiquantitative detection of HPV types and identified the same dominant HPV type in 66.6% of the multiple infections. In conclusion, the TS-PCR-MPG assay significantly increased the rate of detection of HPV DNA and the number of infections with multiple HPV types detected and demonstrated that the prevalence of low-copy-number HPV infections in the anogenital tract may be strongly underestimated by conventional HPV amplification methods, especially in cases of multiple infections. As a consequence, PCR-TS-MPG appears to be highly suited for analysis of the significance of multiple infections in the development of cervical cancer and for the study the natural history and the latency of HPV.