Determination of HPV type 16 and 18 viral load in cervical smears of women referred to colposcopy

Abstract

It has been recognized that human papillomavirus infection is the major causal factor for high-grade cervical lesions. The aim of the study was to evaluate the relationship between HPV 16 and 18 viral loads and cervical status in different age strata. A duplex real time PCR method was devised to determine HPV 16 and 18 viral load per million of human cells using an in house plasmidic construct as a standard of quantification. The 151 cervical scrapes were collected before colposcopic examination from either abnormal cervico-vaginal smear (group 1, 97 patients) or from post treatment clinical follow-up (group 2, 54 patients). In women aged 30-40, the HPV16 viral loads were significantly higher in high-grade squamous intraepithelial lesion than in low-grade squamous intraepithelial lesion in both groups and HPV18 in group 1. In women aged 20-30 of group 1, high HPV viral load was associated in few cases with high-grade squamous intraepithelial lesion or low-grade squamous intraepithelial lesion, and surprisingly in some patients with normal cervix. HPV 16 and 18 viral loads are related to the severity of cervical lesion, and may be useful in the clinical management of cervical lesions. A specific follow-up may be useful for those with high viral load despite normal cervix.