Human Papillomavirus G-Rich Regions as Potential Antiviral Drug Targets.

Herein, we report, for the first time, the screening of several ligands in terms of their ability to bind and stabilize G-quadruplexes (G4) found in seven human Papillomavirus (HPV) genomes. Using a variety of biophysical assays, HPV G-quadruplexes were shown to possess a high degree of structural polymorphism upon ligand binding, which may have an impact on transcription, replication, and viral protein production. A sequence found in high-risk HPV16 genotype folds into multiple non-canonical DNA structures; it was converted into a major G4 conformation upon interaction with a well-characterized highly selective G4 ligand, PhenDC3, which may have an impact on the viral infection. Likewise, HPV57 and 58, which fold into multiple G4 structures, were found to form single stable complexes in the presence of two other G4 ligands, C8 and pyridostatin, respectively. In addition, one of the selected compounds, the acridine derivative C8, demonstrated a significant antiviral effect in HPV18-infected organotypic raft cultures. Altogether, these results indicate that targeting HPV G4s may be an alternative route for the development of novel antiviral therapies.

[An ultrastructural study of the cervix epitelium infected with the human papillomavirus types 16 and 18 before and after treatment with contrasting thermo-laser therapy].

The results of the ultrastructural study of the epithelium of the patient cervix infected by the human papillomavirus (HPV) types 16 and 18 before and after treatment by contrasting thermo-laser therapy (CTLT) are presented. It was shown in this work that 1.5 and 6 months after treatment HPV DNA was not detected in the biopsy and the smear of the cervix using the polymerase chain reaction (PCR). In the ultrathin sections, the structure of the epithelial cells from the biopsy after treatment corresponded to norm. There was effective elimination of HPV types 16 and 18 as Induces by CTLT method.

Human papillomavirus and cervical cancer.

Cervical cancer is caused by human papillomavirus infection. Most human papillomavirus infection is harmless and clears spontaneously but persistent infection with high-risk human papillomavirus (especially type 16) can cause cancer of the cervix, vulva, vagina, anus, penis, and oropharynx. The virus exclusively infects epithelium and produces new viral particles only in fully mature epithelial cells. Human papillomavirus disrupts normal cell-cycle control, promoting uncontrolled cell division and the accumulation of genetic damage. Two effective prophylactic vaccines composed of human papillomavirus type 16 and 18, and human papillomavirus type 16, 18, 6, and 11 virus-like particles have been introduced in many developed countries as a primary prevention strategy. Human papillomavirus testing is clinically valuable for secondary prevention in triaging low-grade cytology and as a test of cure after treatment. More sensitive than cytology, primary screening by human papillomavirus testing could enable screening intervals to be extended. If these prevention strategies can be implemented in developing countries, many thousands of lives could be saved.

Robust production and passaging of infectious HPV in squamous epithelium of primary human keratinocytes.

Using Cre-loxP-mediated recombination, we established a highly efficient and reproducible system that generates autonomous HPV-18 genomes in primary human keratinocytes (PHKs), the organotypic raft cultures of which recapitulated a robust productive program. While E7 promoted S-phase re-entry in numerous suprabasal differentiated cells, HPV DNA unexpectedly amplified following a prolonged G2 arrest in mid- and upper spinous cells. As viral DNA levels intensified, E7 activity diminished and then extinguished. These cells then exited the cell cycle to undergo virion morphogenesis. High titers of progeny virus generated an indistinguishable productive infection in naïve PHK raft cultures as before, never before achieved until now. An immortalization-defective HPV-18 E6 mutant genome was also characterized for the first time. Numerous cells accumulated p53 protein, without inducing apoptosis, but the productive program was severely curtailed. Complementation of mutant genomes by E6-expressing retrovirus restored proper degradation of p53 as well as viral DNA amplification and L1 production. This system will be invaluable for HPV genetic dissection and serves as a faithful ex vivo model for investigating infections and interventions.