Human papillomavirus (HPV) detection in vaginal self-samples: evaluation of eNat® as an alternative suspension medium to ThinPrep®PreservCyt® for vaginal swabs

Human Papillomavirus (HPV) testing on self-collected samples allows for improved coverage rates of cervical cancer (CC) screening programs. ThinPrepRPreservCytR (HOLOGICR, USA) medium is widely used for the suspension of cervical and vaginal self-samples. However, this medium is costly, toxic, and flammable, involving special handling procedures which make its use difficult in screening programs, particularly in low- and middle-income countries. This pilot study aimed to evaluate the analytical performance of eNat R (Copan SpA), an alternative non-alcohol-based suspension medium, compared to ThinPrepRPreservCytR (HOLOGICR) for high-risk HPV (hrHPV) detection in vaginal self-collected swabs using three different real-time polymerase chain reaction (RT-PCR) HPV assays: Anyplex™II HPV28 (Seegene, Korea), PapilloplexR High Risk HPV (GeneFirst, UK), and HPV OncoPredict (Hiantis, Italy). 30 women, referred to colposcopy, were enrolled in this observational, prospective pilot study and asked to collect two vaginal self-taken samples, which were suspended in 5 mL of ThinPrepRPreservCytR or eNatR. Nucleic acids were extracted from 200 L using Microlab Nimbus platform (Seegene, Korea) and tested with the three different RT-PCR full-genotyping high-risk HPV assays. The HPV results of vaginal samples resuspended in the two different media were compared to those obtained from the reference clinician-collected cervical sample from the same woman. hrHPV detection in vaginal self-samples suspended in both media demonstrated a substantial agreement with cervical samples with the three assays under-investigation (0.667 <0.796). Moreover, the discordances between vaginal self-samples collected from the same woman were found only in cases of normal cytology or low-grade cytological lesions and were generally related to low hrHPV viral loads as indicated by the quantitative HPV OncoPredict assay (6.24E+02 copies/10,000 cells). The study's preliminary findings demonstrated a very good agreement between cervical and vaginal self-collected samples suspended in ThinPrepRPreservCytR and eNatR, suggesting that the latter could represent a good alternative medium in HPV screening programs based on self-collection.