Human papillomavirus G-quadruplexes.

Infection with human papillomaviruses (HPVs) is one of the most common sexually transmitted infections and can lead to development of head and neck, skin, and anogenital cancer, including cervical cancer, which represents one of the world's most significant health problems. In this study, we analyze G-rich regions in all known HPV genomes in order to evaluate their potential to fold into G-quadruplex structure. Interestingly, G-rich loci fulfilling the criteria for G-quadruplex formation were found in only 8 types of HPV. Nevertheless, viral G-quadruplexes in 7 sequences derived directly from HPVs are confirmed here for the first time. G-rich regions with the capacity to form G-quadruplexes are located in the LCR, L2, E1, and E4 regions of the HPV genome; therefore we assume that regulation processes in viruses could be affected by G-quadruplex formation. Our results represent a starting point for the design of specific ligands with viral G-quadruplex motifs and suggest novel methods for the control of viral replication and transcription.