Prevalence of Co-infection by Human Papillomavirus, Epstein- Barr Virus and Merkel Cell Polyomavirus in Iranian Oral Cavity Cancer and Pre-malignant Lesions.

Human papillomavirus (HPV) is recognized as the most important risk factor in oral cavity cancer and pre-malignant lesions; however, the etiological association of concomitant infection with other oncogenic viruses as a co-factor has not been definitively proven. The present study aimed to determine the prevalence of co-infection with HPV, Epstein-Barr virus (EBV) and Merkel Cell PolyomaVirus (MCPyV) in oral cavity lesions in Iranian patients. One hundred and fourteen oral cavity samples, including 33 oral squamous cell carcinoma, 28 oral lichen planus, 16 oral epithelial dysplasia and 37 oral irritation fibromas were analyzed for the HPV, EBV and MCPyV infection by quantitative real-time PCR. According to histological features 32.5% and 28.9% of cases were oral irritation fibroma and oral squamous cell carcinoma, respectively. Infection with at least two viruses was detected in 21.1% of patients. In this group, co-infection with HPV/EBV was identified in 37.5% of cases, HPV/MCPyV in 29.2%, EBV/MCPyV in 12.5%, and HPV/EBV/MCPyV in 20.8%. There was no statistically significant difference between multiple infections and anatomical locations of cancer. The prevalence of triple viral infection (HPV/EBV/MCPyV) in well differentiated tumors was higher than EBV or MCPyV single infection. This study revealed that co-infection of HPV, EBV and MCPyV can be detected in both malignant and non-malignant oral cavity tissues, and co-infection with all three viruses in well differentiated tumors can be shown as a synergistic hypothesis of the pathogenic role of these viruses in oral malignant transformation.