Background: HPV infection in young women is common. However only a certain number of HPV genotypes are oncogenic. It is necessary for high risk HPV infection to persist at the cervix for a considerable time before oncogenesis occurs.
Objectives: To look for persistence of high risk HPV in women attending a colposcopy clinic. Two DNA detection methods were used and the results compared to determine the rates of persistent, resolved and acquired infections over a 6-month period. HPV genotyping was used to determine type specific persistence.
Study design: One hundred and thirty-eight women were tested for HPV infection when attending the colposcopy clinic at UCLH and then tested again at a subsequent visit approximately 6 months later. HPV DNA was detected by the Digene HC II assay using the high risk probes only and by PCR with the SPF10 primer set. All SPF10 PCR-positive samples were then specifically genotyped by a Line Probe Assay (LiPA) [Kleter et al. 1999. J. Clin. Microbiol. 1999;37:2508].
Results: At entry of the study high risk HPV was detected in 43% of the samples by Digene HC II and in 60% of the samples by SPF10/LiPA. Thirty-eight (28%) of the women had a true persistent infection with the same high risk HPV genotype over a median period of 6.3 months. Nine (7%) women resolved one HR HPV infection after their first colposcopy visit, but obtained a different high risk HPV infection by the time they were tested at their second visit as identified by LiPA. Thirty-seven (27%) of the 138 women had mixed HPV infections, representing 45% of all those infected.
Conclusions: The SPF10/LiPA assay detected more high risk infections than the Digene HC II assay. The Digene HC II assay was unable to distinguish between persistent infections with the same high risk genotype and those where the genotype had changed between visits.