Phylogeny and Classification of Human Papillomavirus (HPV)16 and HPV18 Variants Based on E6 and L1 genes in Tunisian Women with Cervical Lesions

Abstract

Background: High-risk human papillomavirus (HPV) types are the main etiological factors for cervical cancer.<br />HPV16 and HPV18 are generally the most common forms associated with development of high-grade cervical lesions.<br />This study was undertaken to identify intratypic variants of HPV16 and HPV18 among women with cervical lesions<br />in Tunisia. Materials and Methods: DNA was extracted from cervical samples collected from 49 women. using a<br />PureLinkTM Genomic DNA mini Kit (Invitrogen). E6 and L1 open reading frames (ORF) were amplified by PCR<br />and viral DNA amplicons were subjected to automated sequencing using Big Dye Terminators technology (Applied<br />Biosystems). The obtained sequences were analyzed using an appropriate software program to allow phylogenetic<br />trees to be generated. Results: HPV16 and HPV18 were detected in 15 and 5 cases, respectively. HPV16 E6 sequences<br />clustered with the European German lineage (A2) whereas one isolate diverged differently in the L1 region and<br />clustered with the African sub-lineage (B1). HPV 18 E6 sequences clustered with the European sub-lineage (A1)<br />but L1 sequences clustered as a new clade which diverged from A1-A5. Conclusions: Our results suggest that the<br />distribution of HPV16 and HPV18 sequences in women with cervical lesions in Tunisia is mainly related to European<br />epidemiological conditions and point to the presence of recombinant HPV forms.