Assessment of human papillomavirus mRNA detection over time in cervical specimens collected in liquid based cytology medium

Abstract

Little is known about the stability of human papillomavirus (HPV) RNA within cervical samples collected in liquid based cytology (LBC) preservation media. We addressed this by analysing patient LBC specimens for the presence of HPV RNA over a prospective time course. LBC samples in PreservCyt ® were obtained from seven women referred to colposcopy due to a cytological diagnosis of moderate or severe dyskaryosis. Aliquots were removed and subject to RNA extraction at, 6 h (base-line), 4, 7 and 14 days, post-collection. HPV mRNA was detected using the PreTect ® HPV Proofer, which detects HPV 16, 18, 31, 33 and 45 E6/E7 transcripts and human small ribonucleoprotein U1A mRNA as a sample control. HPV DNA genotyping was also performed at base-line to assess the range of types in our group. In addition to assessment of viral RNA, overall integrity of the cellular RNA extract was analysed by the RNA 6000 pico assay. Control human RNA was amplified successfully in all seven samples at each time point. Five of the seven women were HPV positive for E6/E7 viral transcripts at base-line and positivity was maintained in all five up to 14 days. Although the pattern of cellular RNA profiles generated from the samples was variable, results indicated that this extract could be amenable to gene expression profiling and that degradation did not increase as a result of storage time. It is concluded that HPV RNA in routinely collected LBC specimens in PreservCyt ® can be detected for at least 14 days from sample collection.