Exploring the association between the lineages of human papillomavirus type 16 and viral physical status in the development of cervical cancer in Iran.

Human papillomaviruses (HPVs) are well-established etiological causes of invasive cervical cancer (ICC), with type 16 being the main contributor. This virus is often found to be integrated into the host genome in precancerous lesions and advanced cervical cancers. It is suggested that distinct lineages of HPV-16 differ in their persistence, carcinogenic potential, and geographic distribution. Given that genomic integration is one of the most critical steps in the development of cervical cancer, and lineage D has a higher propensity to integrate the viral genome into the host genome, it is necessary to conduct a study to investigate a possible relationship between HPV-16 lineages and physical status in Iran. In this study, a total of 125 laboratory-confirmed HPV-16-positive cervical samples (comprising 30 normal, 39 precancerous, and 56 cancerous specimens) were analyzed. The DNA level of E2 and E6 viral genes was measured using the quantitative Real-Time PCR method, and the E2/E6 ratio was used to calculate the physical status of the HPV-16 DNA in the studied samples. The full sequence of the E6 gene was also sequenced to determine HPV-16 lineages. Three lineages, A (32.8%), C (0.8%), and D (66.4%) of HPV-16, were found in this study. HPV-16 exhibits different integration profiles, with viral DNA detected in three forms: episomal, mixed, and integrated. The physical status of the genome was statistically different based on histology and age. The integrated form was more prevalent in ICC patients than in CIN I-III and normal groups (P=0.000048). Also, the integrated form of the genome was found in higher amounts in the age group >40 years in comparison to <40 years (P= 0.00117). Regarding lineages, no statistically significant differences were identified between HPV-16 lineages and the integration status. However, when the samples were stratified by histology status, an association between lineage D and integrated form was observed, while no association was found for lineage A. In conclusion, lineages A and D were found to be dominant in the Iranian population. Moreover, an association was found between lineage and integration status, as lineage D has a higher propensity to integrate than lineage A. However, it is recommended that further studies with larger sample sizes from different regions of Iran be conducted to estimate whether a specific lineage or sublineage has a higher chance of integrating into the host genome, persisting, and causing cancer.