Molecular Characterization of HPV16 E6 and E7 Variants among Women with Cervical Cancer in Morocco

Abstract

Aims: Human papillomavirus type 16 (HPV16) is the primary etiological agent of cervical cancer. The variations in the amino acid sequence of the HPV16 E6 and E7 oncoproteins are known to correlate with both their oncogenic potential and geographic distribution. Study Design: The present study was designed to analyze sequence variations in E6 and E7 genes of HPV16 in order to evaluate the intratype variants circulating in our population. Methodology: The entire E6 and E7 genes of 31 HPV16 isolates from Moroccan patients with cervical cancer were sequenced and analyzed. Results: Sequence analysis of HPV16-E6 showed a high prevalence (64.5%) of the African lineage. The European and the North-American variants were detected in respectively 19.4% and 16% of the HPV16 positive specimens. At the amino acid level, the most prevalent missense mutations revealed in the E6 gene were H78Y, Q14D, L83V, R10I and Q14H. Our data also showed that E7 appeared to be better conserved as compared to E6, with a high frequency of two silent variations at G789A and T795C nucleotides and one hot spot of E7 nucleotide variation A647G leading to N29S. Conclusion: The present study provides a new data on the genetic diversity of HPV16 and highlights the possible association between the high prevalence of HPV16 African variants and the high incidence of cervical cancer in Morocco.