Effect of time and temperature on the stability of HPV and cellular nucleic acid using simulated dry self-samples.

Background: Self-sampling is now a key component within HPV-based cervical screening programmes to engage individuals and enhance participation. As self-sampling is relatively new, information on the influence of pre-analytical parameters such as transit-temperature and time between sampling and testing on HPV test results requires detailed investigation.

Methods: FLOQSwabs® and Evalyn Brushes® were used to assess HPV and cellular stability over a 30-week period (0w,4w,12w,30w) at 4 °C, ambient, and 37 °C. Vaginal self-samples were simulated by inoculating the devices with an HPV16-positive cell-line suspension. Devices were tested using two DNA-based (Anyplex™ II HPV28, Papilloplex® HR-HPV), one mRNA-based (APTIMA HR-HPV,) and one in-house beta-globin qPCR assay.

Results: No loss of qualitative HPV detection was observed after 12-weeks storage at ambient or 4°C irrespective of device or assay. For DNA-based assays, no loss of qualitative HPV detection was observed over time (30w) irrespective of temperature/device. Loss of qualitative mRNA signal was observed when devices were stored at 37°C for 12-weeks or longer; however, no loss of detection was observed at 30-weeks when either device was stored at 4°C.

Conclusion: HPV nucleic acid is stable on proxies of self-taken samples, however, the duration of stability was affected by the device and storage conditions. Such differences should be considered when optimising self-sampling exercises.