OBJECTIVES: Most of human papilomavirus (HPV) infections are “cleared” by the immune system, however, in cases of immune system suppression infections could lead to development of malignancies. The aim of this study was to find out the frequency of HR-HPV infection in early period after renal transplantation in Latvian recipients receiving immunosuppressive therapy and to follow the progression of the infection up to one year. METHODS: 43 female renal recipients (median age of 48 IQR= 39-58) and 79 practically healthy female individuals (median age of 48 IQR= 42-57) as a control group were enrolled in this investigation. For the detection of HPV infection patients' samples (blood and vaginal swabs) where collected two weeks after transplantation with following collection of six months and one year. Different polymerase chain reactions for HR-HPV genomic sequences detection and commercial ELISA kit for detection of anti-HPV IgG antibodies were used. RESULTS: In this study we show that frequency rate of HR-HPV infection has increased by the one year after transplantation from early stage of immumosuppressive therapy (from 24% to 36%). Also increase of HR-HPV load was detected over the time, showing the highest median viral load at sixth month after transplantation. CONCLUSIONS: From the obtained data follows that it is very important to carefully monitor patients receiving immunosuppression therapy on progression of HR-HPV. In the case of this viral infection presence, immunosuppressive therapy must be attentively adjusted to avoid the HR-HPV infection rapid progression with the subsequent development of CIN or cervical cancer.

The potential to affect gene expression via G-quadruplex stabilization has been extended to all domains of life, including viruses. Here, we investigate the polymorphism and structures of G-quadruplexes of the human papillomavirus type 52 with UV, CD and NMR spectroscopy and gel electrophoresis. We show that oligonucleotide with five G-tracts folds into several structures and that naturally occurring single nucleotide polymorphisms (SNPs) have profound effects on the structural polymorphism in the context of G-quadruplex forming propensity, conformational heterogeneity and folding stability. With help of SNP analysis, we were able to select one of the predominant forms, formed by G-rich sequence d(G3TAG3CAG4ACACAG3T). This oligonucleotide termed HPV52(1-4) adopts a three G-quartet snap back (3+1) type scaffold with four syn guanine residues, two edgewise loops spanning the same groove, a no-residue V loop and a propeller type loop. The first guanine residue is incorporated in the central G-quartet and all four-guanine residues from G4 stretch are included in the three quartet G-quadruplex core. Modification studies identified several structural elements that are important for stabilization of the described G-quadruplex fold. Our results expand set of G-rich targets in viral genomes and address the fundamental questions regarding folding of G-rich sequences.

The incidence of human papillomavirus-related head and neck squamous cell carcinoma (HPV+HNSCC) has reached epidemic levels in the last decade. While prophylactic vaccines will prevent future HPV infections, there are currently no HPV-specific antiviral drugs to treat current HPV infections or HPV+HNSCC. HPV replication and transcription are promising targets for anti-HPV therapeutics, as modulation of these processes can alter expression levels of HPV E6 and E7, which are required for maintenance of the transformed phenotype. This is a particularly attractive target in in HPV+HNSCC where the majority of tumors have episomal genomes replicating in an E1-E2 dependent manner. Here, we describe a model system to study HPV16 E1-E2 mediated DNA replication and HPV16 E2-mediated transcriptional activation and repression in multiple HNSCC cell lines. Our results demonstrate that low levels of IFIT1 are required for HPV16 replication in HNSCC cell lines and HPV16 E1 interacts with IFIT1. Restoration of IFIT1 expression in HNSCC cell lines partially inhibits HPV16 E1-E2 mediated replication. This system can be used to study replication and transcription by HPV16 E1 and E2 in HNSCC as well as be utilized to screen potential anti-HPV therapeutics that target HPV16 replication and transcription.

Epstein–Barr virus (EBV) has been recently shown to be co-present with high-risk human papillomaviruses (HPVs) in human cervical cancer; thus, these oncoviruses play an important role in the initiation and/or progression of this cancer. Accordingly, our group has recently viewed the presence and genotyping distribution of high-risk HPVs in cervical cancer in Syrian women; our data pointed out that HPVs are present in 95.45% of our samples. Herein, we aim to explore the co-prevalence of EBV and high-risk HPVs in 44 cervical cancer tissues from Syrian women using polymerase chain reaction (PCR), immunohistochemistry (IHC) and tissue microarray (TMA) analyses. We found that EBV and high-risk HPVs are co-present in 15/44 (34%) of the samples. Additionally, we report that the co-expression of LMP1 and E6 genes of EBV and high-risk HPVs, respectively, is associated with poorly differentiated squamous cell carcinomas phenotype; this is accompanied by a strong and diffused Id-1 overexpression, which is an important regulator of cell invasion and metastasis. These data imply that EBV and HPVs are co-present in cervical cancer in the Middle East area including Syria and their co-presence is associated with a more aggressive cancer phenotype. Future investigations are needed to elucidate the exact role of EBV and HPVs cooperation in cervical carcinogenesis.