Figure 1: An electropherogram of 2nd nested PCR products. The 457 bp and 322 bp fragments correspond to amplified HPV-16 and HPV-18 DNA, respectively. Lane M: 50 bp molecular size marker; NC: negative control (nuclease-free water); PC: positive control (HPV-16 plasmid DNA); S1, S2, S4, S5, S6, and S7: HPV-16 DNA positive samples; S3: HPV-16 and HPV-18 DNA coinfection (a PCR product ranging from 322 bp to 457 bp).