One virus, one lesion--individual components of CIN lesions contain a specific HPV type

In 20-40% of cervical intra-epithelial neoplasia (CIN) and in 4-8% of cervical carcinoma tissue specimens, multiple HPV genotypes have been detected. Whole tissue section (WTS) PCR does not determine how the individual types relate causally to complex and multiple CIN. Our objective was to determine whether laser capture micro-dissection (LCM) with HPV PCR genotyping (LCM-PCR) could accurately recover type-specific HPV DNA from epithelial cells in individual areas of CIN and normal epithelium, and whether one or more viruses are present in one lesion. For that, histologically selected samples of CIN and normal epithelium were isolated by LCM and analysed by the SPF(10) PCR/LiPA(25) (version 1) HPV genotyping system for 25 HPV genotypes. HPV genotypes detected in 756 areas of CIN (grade 1, 2 or 3) by LCM-PCR were compared with results obtained by WTS-PCR in 60 cases (74 biopsies). We showed that when a single HPV type is detected by WTS-PCR, that type was almost always (94%; 29/31) recovered by LCM-PCR from CIN. When multiple HPV types were present by WTS-PCR, their distribution within histological sections could be mapped by LCM-PCR. Association of a single HPV type with a discrete area of CIN was found for 93% (372/399) of LCM fragments analysed by PCR. We found colliding CIN lesions associated with separate HPV types and only 62% (61/99) of HPV types detected by WTS-PCR were found in CIN by LCM-PCR. Therefore, the LCM-PCR technique was found very accurate for high-resolution HPV genotyping and for assigning an individual HPV type to an area of CIN. At LCM level, in cervical biopsy sections with multiple HPV infections, the relation between HPV types and CIN lesions is often complex. Almost every HPV type found in CIN by LCM-PCR is associated with a biological separate independent CIN lesion-one virus, one lesion.