Physical state & copy number of high risk human papillomavirus type 16 DNA in progression of cervical cancer.

ABSTRACT

Background & objectives: High-risk human papilloma virus (HR-HPV) infection and its integration in host genome is a key event in malignant transformation of cervical cells. HPV16 being a dominant HR-HPV type, we undertook this study to analyze if viral load and physical state of the virus correlated with each other in the absence of other confounding variables and examined their potential as predictors of progressive cervical lesions. Methods: Both, viral load and integration status of HPV16 were determined by real time URR PCR and estimation of E2E6 ratio in a total of 130 PGMY-RLB -confirmed, monotypic HPV16-infected cervical DNA samples from biopsies of cytology-confirmed low grade (LSIL, 30) and high grade (HSIL, 30), and invasive carcinoma, (squamous cell carcinoma SCC, 70) cases. Results: Investigation of DNA samples revealed a gradual increase in HPV16 viral load over several magnitudes and increased frequency of integration from LSIL to HSIL and HSIL to invasive cancer in relation to the severity of lesions in monotypic HPV16-infected cervical tissues. In a substantial number of precancer (11/60) and cancer cases (29/70), HPV16 was detected in concomitant mixed form. The concomitant form of HPV16 genome carried significantly higher viral load. Interpretation & conclusions: Overall, viral load and integration increased with disease severity and could be useful biomarkers in disease progression, at least, in HPV16-infected cervical pre-cancer and cancer lesions.