Co-mutation of HPV16 E6 and E7 genes in Thai squamous cervical carcinomas.

Infection with high-risk HPV16 is well associated with invasive cervical carcinomas. Variations in the E6 gene of HPV16 are shown to correlate with both the geographical areas and the oncogenicity. Here, we have characterized HPV16 DNA variants in the E6 and E7 coding regions of 31 Thai cervical squamous cell carcinomas. Five groups of E6 variants were identified. A mutation from T to G at nucleotide 178, leading to a change from aspartate to glutamate (D25E), was the most common variation accounting for 70%. Interestingly, 90% of these E6 (D25E) variants coincided with a specific type of E7 mutation, N29S. This is the first finding of coordinated change between E6 (D25E) and E7 (N29S) in HPV, which might indicate a specific variant for the Thai population. These comutations may not only represent an area-specific strain but may also be valuable for studying the virus and developing a suitable vaccine in Thailand.