Human Papilloma Virus Analysis of HPV FISH patterns in low and high grade Cervical Intraepithelial Neoplasia

Abstract

Human Papilloma Virus is the most common sexually transmitted infection, with an
estimated 80% of sexually active men and women acquiring an infection at some point
in their lifetime. 10-20% of infected individuals can not clear this infection effectively
and consequentially are at risk for progression of Cervical Intraepithelial Neoplasia
(CIN) to cancer. Presence of HPV can be determined using PCR and/or (Fluorescence) In
Situ Hybridization. The aim of the performed experiments was to determine the general
FISH patterns that are specifically linked to low grade and high grade CIN lesions and to
investigate whether or not these patterns could be used to grade these lesions.
12 formalin fixed and paraffin embedded sections from one patient and 30 formalin fixed
and paraffin embedded sections from different patients where used to perform a FISH
procedure and to analyze the general FISH hybridization pattern for CIN 1,2 and 3. For the
analysis 3 distinct patterns for the physical status of the virus were determined: episomal,
integrated and mixed pattern. Also the presence of replication, load and the ratio between
basal load and superficial load was analyzed to determine the general pattern.
Results show that load and physical status of the virus are not associated with the severity
of the lesions. High loads are present in both high and low grade lesions. Also physical
status of the virus is not different for the sections, episomal and mixed patterns are found
in low and high grades. Only integrated pattern is a marker for severity, as this is only found
in CIN 3. Presence of replication is most common in CIN 1, this might contribute to correct
grading. The ratio between the load in the Basal layer and the load in the superficial layer
is the most informative discriminant of severity: <0.5 for CIN 1, 0.5<load<1 for CIN 2 and 1
for CIN 3. Based on these results it is possible to classify the severity of the lesion