The droplet digital PCR (ddPCR) system enables high-sensitivity detection of nucleic acids and direct absolute quantification of the targets. The aim of this research was to evaluate this system for viral load (VL) analysis of the human papillomavirus (HPV) genotypes HPV31, 35, 39, 51 and 56 measured in number of viral particles per cell. The sample types used for the optimization of the ddPCR assay were formalin-fixed paraffin-embedded (FFPE) tissues and cervical liquid cytology samples. The presently optimized ddPCR assays, together with assays optimized previously for HPV16, 18, 33 and 45, with the same ddPCR method, were used for the VL analysis of cervical tumor samples. Results published previously on the present study cohort showed that women with a cervical tumor containing multiple high-risk HPV genotypes had a worse prognosis compared to women with single-genotype-infected tumors. The VL was therefore analyzed in this study for the same cohort, as a possible explanatory factor to the prognostic differences. The results of the optimization part of the study, with analysis of VL using ddPCR in DNA from varying sample types (FFPE and liquid cytology samples), showed that each of the five assays demonstrated good inter- and intra-assay means with a coefficient of variation (CV) under 8% and 6% respectably. The cohort results showed no difference in VL between tumors with multiple and single HPV infections, and therefore did most likely not constitute a contributing factor for prognostic differences observed previously. However, tumors from women aged 60 years or older or containing certain HPV genotypes and genotype genera were associated with a higher VL.
Background: An updated screening algorithm was introduced in Sweden 2015. Primary HPV test for women >30 years old and a prolonged screening with the last test after 64 years of age were some of ...
Örebro County introduced an updated screening program 2016 with primary HPV test for women over 30 years and prolonged screening, increasing the cut-off age from 56-60 to 64-70. The aim of this study was to investigate the prevalence of HPV genotypes and their correlation to histological changes in women, 10 years after exclusion from the screening program, due to an eventual implementation of a catch-up program including all women aged 60-70.All women in Örebro County, born 1,946 (n = 1,968), were invited to a liquid-based cell sample with primary HPV screening. Samples were analyzed for hrHPV mRNA and positive samples were genotyped. hrHPV positive women were offered to do a conization.Out of 809 participants, 31 (3.8%) were hrHPV positive, of these 22 did a conization. Histologically, 5/22 (23%) had LSIL and 5/22 (23%) had HSIL. Normal histology was found in 12/22 (55%). The most prevalent genotypes were HPV 16, 33, 52, 56, and 68. Of the women with HSIL, one case of cervical cancer was confirmed in a recone biopsy after 4 months.The study showed considerable prevalence of hrHPV and histologically confirmed LSIL/HSIL. These data led to catch-up screening for women between 60 and 70 years when overlapping two screening strategies.
