Immunohistochemical and molecular detection of High Risk Human Papilloma Virus (HR-HPV), among Patients with Oral Lesions in Khartoum State

Abstract

Background High Risk human papillomaviruses (HR-HPV), subtypes are strongly linked to etiology of many human cancers including oral cancer. The epidemiology of infection with different HPV genotypes greatly varies in different countries. In Sudan, there are considerable numbers of oral cancers, most of them are attributed to the use of Tobacco (toombak) use and alcohol consumption is the main risk factors for oral cancers (OCs). Other risk factor includes the viral infection, particularly with Human papilloma virus (HPV). Aim The aim of this study was to identify and genotype the HR-HPV subtypes in oral tissues obtained from Khartoum State with oral lesions. Material and methods This is a prospective analytical case control study conducted at Khartoum State during the period from June 2010 to December 2013. Two hundred tissue blocks were retrieved from different histopathology laboratories in Khartoum State. Of the 200 formalin fixed paraffin wax processed tissue blocks, 100 were obtained from patients diagnosed with oral cancer and 100 samples were obtained from patients diagnosed with non-neoplastic lesions. Infection with HPV was initially determined using p16INK4A as a biomarker immunohistochemistry (IHC) method, and then genotyping was subsequently assessed applying polymerase chain reaction (PCR). Tumor DNA was amplified using PCR with HR-HPV consensus and multiplex primers. Cytokeratin 19 (CK19) antibodies was used to study the expression pattern in normal mucosa, dysplasias, and oral squamous cell carcinomas (OSCC), using IHC. Results HPV genomic materials using A6 and A7 primers were detected in 12/200 (6%) of oral lesions. Of these, 6/12 (50%) HPV-16, 4/12 (34%) HPV-18, 1/12 (8%) HPV-31, and 1/12(8%) HPV-33. Out of the 12 HPV; 8/12(66.7%) HPV were found in malignant lesions, whereas, 4/12(33.3%) HPV were found in benign lesions. Consequently, the risk associated with HPV infection was found to be statistically significant (P<0.001). The age group 40-49 years was the most susceptible to HPV infection. According to relation between HPV and lesion sites, the most affected sites were buccal mucosa and oropharynx, particularly, SCCs, hence, most of benign lesions were seen in the salivary glands. The detected HR-HPV were type 16, 18, 31 and 33. The total number of cases detected by the PCR HPV genotyping were 12 cases, out of these 11(91.7%), were detected by p16, Statistically, P16 was significantly associated with HPV the (P<0.005). Conclusion In conclusion, the findings of this study provide strong association between HPV and OCs, amongst Sudanese patients. HPV particularly subtypes 16 and 18 play a role in the etiology of oral cancer in the Sudan. On the other hand, in this study P16INK4A immunostaining was used to screen tissue samples obtained from patients with oral lesions to indicate the presence of HPV infection. But the exact role of CK19 in the genesis of HPV requires further assessment.