Whole tissue cervical mapping of HPV infection: Molecular evidence for focal latent HPV infection in humans

Abstract

In this study, we aimed to provide molecular evidence of HPV latency in humans and discuss potential challenges of conducting studies on latency. We analyzed the entire cervix of two women who underwent hysterectomy unrelated to cervical abnormality. The cervices were sectioned into 242 and 186 sets respectively, and each set was tested separately for HPV using the SPF10-PCR-DEIA-LiPA25 system. To identify whether there was any evidence of transforming or productive infection, we used the biomarkers E4 and P16^INK4a to stain slides immediately adjacent to HPV-positive sections. HPV was detected in both cervices. In patient 1, 1/242 sets was positive for HPV31. In patient 2, 13/186 sets were positive for HPV18 and 1/186 was positive for HPV53. The infection was very focal in both patients, and there was no sign of a transforming or productive infection, as evaluated by the markers E4 and P16^INK4a. Had we only analyzed one set from each block, the probability of detecting the infection would have been 32.3% and 2%, respectively.Our findings support the idea that HPV may be able to establish latency in the human cervix; however, the risk associated with a latent HPV infection remains unclear.

Keywords: HPV; Humans; Molecular biology; Papillomavirus; Uterine cervical neoplasm; Virus latency.

Fig. 1

Overview of the sampling procedure.

Fig. 2

Overview of the sectioning protocol. One set consists of an H&E slide (4 µm), a tube with 3 sections for HPV PCR (PCR 3 × 8 µm), and 4 blank slides (4 × 1 × 4 µm) for additional analysis.

Fig. 3

Distribution of HPV in the human uterine cervix. Each pie chart illustrates the cervix seen from the vagina and the location of the HPV-positive test results. The central white circle illustrates the cervical orifice (i.e. opening to the uterine cavity). Each large pie piece represents a 3-mm block and each smaller slice represents a whole tissue section set tested by SPF₁₀ PCR.