Molecular analysis of HPV 16 E6I/E6II spliced mRNAs and correlation with the viral physical state and the grade of the cervical lesion

Abstract

The presence of HPV 16 E6*I/E6*II spliced transcripts, in cervical lesions of different grade, was analyzed to characterize the transcription pattern. The presence and amount of spliced transcripts were correlated with DNA viral markers such as E2/E6 ratio and physical state. The detection of HPV 16 E6*I/E6*II mRNAs was set up by an SYBR Green real-time reverse transcriptase PCR assay with an optimal dynamic range and sensitivity. The assay was applied to the analysis of 71 specimens, positive to HPV 16 as a sole infection, from women with abnormal cervical smears, precisely 31 low-grade squamous intraepithelial lesions and 40 high-grade lesions. Samples negative to both transcripts were found only in low-grade cervical lesions. Three different transcription profiles were found in the low- and high-grade lesions analyzed: in low-grade lesions samples positive only to E6*II and in high-grade lesions samples positive only to E6*I were detected. In low- and high-grade lesions, samples positive to both E6*I and E6*II were found. In the samples positive for both transcripts, the E6*I/E6*II ratio was higher than that in the majority of high-grade lesions and lower than that in all the low-grade lesions. Analyzing the transcription pattern in relation to E2/E6 ratio and to the DNA physical state, the presence of high values of E6*I was associated mainly with low values of E2/E6 ratio and of mixed DNA forms. The detection of HPV 16 E6*I/E6*II mRNAs may serve to identify transcription patterns indicative of cervical disease progression and help physicians to decide clinical management.