Are There More Human Cancer Viruses Left to Be Found?

Of the thousands of viruses infecting humans, only seven cause cancer in the general population. Tumor sequencing is now a common cancer medicine procedure, and so it seems likely that more human cancer viruses already would have been found if they exist. Here, we review cancer characteristics that can inform a dedicated search for new cancer viruses, focusing on Kaposi sarcoma herpesvirus and Merkel cell polyomavirus as the most recent examples of successful genomic and transcriptomic searches. We emphasize the importance of epidemiology in determining which cancers to examine and describe approaches to virus discovery. Barriers to virus discovery, such as novel genomes and viral suppression of messenger RNA expression, may exist that prevent virus discovery using existing approaches. Optimally virus hunting should be performed in such a way that if no virus is found, the tumor can be reasonably excluded from having an infectious etiology and new information about the biology of the tumor can be found.

The impact of DNA tumor viruses in low-to-middle income countries (LMICS): A literature review.

DNA viruses are common in the human population and act as aetiological agents of cancer on a large scale globally. They include the human papillomaviruses (HPV), Epstein-Barr virus (EBV), Kaposi sarcoma-associated herpesvirus (KSHV), hepatitis viruses, and human polyomaviruses. Oncogenic viruses employ different mechanisms to induce cancer. Notably, cancer only develops in a minority of individuals who are infected, usually following protracted years of chronic infection. The human papillomaviruses (HPVs) are associated with the highest number of cancer cases, including cervical cancer and other epithelial malignancies. Hepatitis B virus (HBV) and the RNA virus hepatitis C (HCV) are significant contributors to hepatocellular cancer (HCC). Other oncoviruses include Epstein-Barr virus (EBV), Kaposi sarcoma-associated herpes virus (KSHV), human T-cell leukemia virus (HTLV-I), and Merkel cell polyomavirus (MCPyV). The identification of these infectious agents as aetiological agents for cancer has led to reductions in cancer incidence through preventive interventions such as HBV and HPV vaccination, HPV-DNA based cervical cancer screening, antiviral treatments for chronic HBV and HCV infections, and screening of blood for transfusion for HBV and HCV. Successful efforts to identify additional oncogenic viruses in human cancer may provide further understanding of the aetiology and development of cancer, and novel approaches for prevention and treatment. Cervical cancer, caused by HPV, is the leading gynaecological malignancy in LMICs, with high age-standardised incidence and mortality rates, HCC due to HBV is an important cause of cancer deaths, and the burden of other cancer attributable to infections continues to rise globally. Hence, cancers attributable to DNA viruses have become a significant global health challenge. These viruses hence warrant continued attention and interrogation as efforts to understand them further and device further preventive interventions are critical.

Epigenetic Mechanisms in Latent Epstein-Barr Virus Infection and Associated Cancers.

The Epstein-Barr Virus (EBV) is a double-stranded DNA-based human tumor virus that was first isolated in 1964 from lymphoma biopsies. Since its initial discovery, EBV has been identified as a major contributor to numerous cancers and chronic autoimmune disorders. The virus is particularly efficient at infecting B-cells but can also infect epithelial cells, utilizing an array of epigenetic strategies to establish long-term latent infection. The association with histone modifications, alteration of DNA methylation patterns in host and viral genomes, and microRNA targeting of host cell factors are core epigenetic strategies that drive interactions between host and virus, which are necessary for viral persistence and progression of EBV-associated diseases. Therefore, understanding epigenetic regulation and its role in post-entry viral dynamics is an elusive area of EBV research. Here, we present current outlooks of EBV epigenetic regulation as it pertains to viral interactions with its host during latent infection and its propensity to induce tumorigenesis. We review the important epigenetic regulators of EBV latency and explore how the strategies involved during latent infection drive differential epigenetic profiles and host-virus interactions in EBV-associated cancers.

Deciphering the role of HPV-mediated metabolic regulation in shaping the tumor microenvironment and its implications for immunotherapy in HNSCC.

Head and neck squamous cell carcinoma (HNSCC), as a complex and variable malignancy, poses a significant threat to human health. Since the intricate association between HPV and HNSCC emerged, its role within the TME has garnered extensive attention. HPV+HNSCC exhibits distinct immunological characteristics within the TME, intricately intertwined with mechanisms of immune evasion. HPV employs multifaceted pathways to intervene in metabolic regulation within the TME, exerting influence over immune cell functionality and neoplastic cell genesis. Furthermore, the heightened immune reactivity exhibited by HPV+HNSCC within the TME augments responses to immune interventions such as immune checkpoint inhibitors. Therefore, amidst the current limitations of therapeutic approaches, immunotherapy stands as a promising strategy to overcome the conventional confines of treating HNSCC. This article comprehensively outlines the impact of HPV on the inception and progression of HNSCC while discussing the amalgamation of metabolic regulation within the TME and immunotherapeutic strategies. By intervening in the reciprocal interactions between HPV and HNSCC within the TME, the potential to modulate the efficacy of immune-based treatments becomes evident. Concurrently, a synthesis of pertinent biomarker development is summarized. Such endeavors hold paramount significance for personalized therapeutic approaches and the more effective management of HNSCC patients.

Construction of a diagnostic model for hepatitis B-related hepatocellular carcinoma using machine learning and artificial neural networks and revealing the correlation by immunoassay.

HBV infection profoundly escalates hepatocellular carcinoma (HCC) susceptibility, responsible for a majority of HCC cases. HBV-driven immune-mediated hepatocyte impairment significantly fuels HCC progression. Regrettably, inconspicuous early HCC symptoms often culminate in belated diagnoses. Nevertheless, surgically treated early-stage HCC patients relish augmented five-year survival rates. In contrast, advanced HCC exhibits feeble responses to conventional interventions like radiotherapy, chemotherapy, and surgery, leading to diminished survival rates. This investigation endeavors to unearth diagnostic hallmark genes for HBV-HCC leveraging a bioinformatics framework, thus refining early HBV-HCC detection. Candidate genes were sieved via differential analysis and Weighted Gene Co-Expression Network Analysis (WGCNA). Employing three distinct machine learning algorithms unearthed three feature genes (HHIP, CXCL14, and CDHR2). Melding these genes yielded an innovative Artificial Neural Network (ANN) diagnostic blueprint, portending to alleviate patient encumbrance and elevate life quality. Immunoassay scrutiny unveiled accentuated immune damage in HBV-HCC patients relative to solitary HCC. Through consensus clustering, HBV-HCC was stratified into two subtypes (C1 and C2), the latter potentially indicating milder immune impairment. The diagnostic model grounded in these feature genes showcased robust and transferrable prognostic potentialities, introducing a novel outlook for early HBV-HCC diagnosis. This exhaustive immunological odyssey stands poised to expedite immunotherapeutic curatives' emergence for HBV-HCC.

Small DNA tumor viruses and human cancer: Preclinical models of virus infection and disease.

Human tumor viruses cause various human cancers that account for at least 15% of the global cancer burden. Among the currently identified human tumor viruses, two are small DNA tumor viruses: human papillomaviruses (HPVs) and Merkel cell polyomavirus (MCPyV). The study of small DNA tumor viruses (adenoviruses, polyomaviruses, and papillomaviruses) has facilitated several significant biological discoveries and established some of the first animal models of virus-associated cancers. The development and use of preclinical in vivo models to study HPVs and MCPyV and their role in human cancer is the focus of this review. Important considerations in the design of animal models of small DNA tumor virus infection and disease, including host range, cell tropism, choice of virus isolates, and the ability to recapitulate human disease, are presented. The types of infection-based and transgenic model strategies that are used to study HPVs and MCPyV, including their strengths and limitations, are also discussed. An overview of the current models that exist to study HPV and MCPyV infection and neoplastic disease are highlighted. These comparative models provide valuable platforms to study various aspects of virus-associated human disease and will continue to expand knowledge of human tumor viruses and their relationship with their hosts.

Molecular Mechanisms of Flavonoids against Tumor Gamma-Herpesviruses and Their Correlated Cancers-A Focus on EBV and KSHV Life Cycles and Carcinogenesis.

Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) are cancer-causing viruses that belong to human gamma-herpesviruses. They are DNA viruses known to establish lifelong infections in humans, with the ability to develop various types of cancer. Drug resistance remains the main barrier to achieving effective therapies for viral infections and cancer. Thus, new medications with dual antiviral and anticancer actions are highly needed. Flavonoids are secondary metabolites biosynthesized by plants with diverse therapeutic effects on human health. In this review, we feature the potential role of flavonoids (flavones, protoflavones, isoflavones, flavanones, flavonols, dihydroflavonols, catechins, chalcones, anthocyanins, and other flavonoid-type compounds) in controlling gamma-herpesvirus-associated cancers by blocking EBV and KSHV infections and inhibiting the formation and growth of the correlated tumors, such as nasopharyngeal carcinoma, Burkitt's lymphoma, gastric cancer, extranodal NK/T-cell lymphoma, squamous cell carcinoma, Kaposi sarcoma, and primary effusion lymphoma. The underlying mechanisms via targeting EBV and KSHV life cycles and carcinogenesis are highlighted. Moreover, the effective concentrations or doses are emphasized.

Simultaneous detection and differentiation of three oncogenic viral diseases of chicken by use of multiplex PCR.

Avian oncogenic or tumor diseases are common in poultry industry causing significant economic loss. Marek's disease (MD), avian leukosis (AL) and Reticuloendotheliosis (RE) are the three major viral oncogenic infections that are difficult to differentiate with gross lesions. Multiplex PCR for simultaneous detection and differentiation of these three viruses was developed and validated. The primers targeting the genes of pp38, pol and LTR for MDV, ALV and REV were designed to yield 206, 429, and 128 bp, respectively. The sensitivity of the PCR primers was checked with serial dilution of positive template DNA for each virus and found to be in the range of 10-5 to 10-7 of 1 µg/µl of initial template DNA. Out of 114 suspected tumor samples screened, 8 samples were positive for MDV, 13 samples were positive for ALV and 31 samples positive for REV. Five samples were positive for both MD and ALV; 3 samples were positive for MD and REV and 25 samples were positive for ALV and REV. Eight samples were positive for all three viruses. Multiplex PCR demonstrated to be a useful technique for simultaneous, rapid detection and differentiation of major tumor causing and immunosuppressive viral diseases of chicken.

Applications of mass spectrometry imaging in virus research.

Mass spectrometry imaging (MSI) is a label-free molecular imaging technique allowing an untargeted detection of a broad range of biomolecules and xenobiotics. MSI enables imaging of the spatial distribution of proteins, peptides, lipids and metabolites from a wide range of samples. To date, this technique is commonly applied to tissue sections in cancer diagnostics and biomarker development, but also molecular histology in general. Advances in the methodology and bioinformatics improved the resolution of MS images below the single cell level and increased the flexibility of the workflow. However, MSI-based research in virology is just starting to gain momentum and its full potential has not been exploited yet. In this review, we discuss the main applications of MSI in virology. We review important aspects of matrix-assisted laser desorption/ionization (MALDI) MSI, the most widely used MSI technique in virology. In addition, we summarize relevant literature on MSI studies that aim to unravel virus-host interactions and virus pathogenesis, to elucidate antiviral drug kinetics and to improve current viral disease diagnostics. Collectively, these studies strongly improve our general understanding of virus-induced changes in the proteome, metabolome and metabolite distribution in host tissues of humans, animals and plants upon infection. Furthermore, latest MSI research provided important insights into the drug distribution and distribution kinetics, especially in antiretroviral research. Finally, MSI-based investigations of oncogenic viruses greatly increased our knowledge on tumor mass signatures and facilitated the identification of cancer biomarkers.

The Merkel Cell Polyomavirus T Antigens Function as Tumor Promoters in Murine Skin.

Merkel cell polyomavirus (MCPyV) causes the majority of human Merkel cell carcinomas (MCC), a rare but highly aggressive form of skin cancer. We recently reported that constitutive expression of MCC tumor-derived MCPyV tumor (T) antigens in the skin of transgenic mice leads to hyperplasia, increased proliferation, and spontaneous epithelial tumor development. We sought to evaluate how the MCPyV T antigens contribute to tumor formation in vivo using a classical, multi-stage model for squamous cell carcinoma development. In this model, two chemical carcinogens, DMBA and TPA, contribute to two distinct phases of carcinogenesis-initiation and promotion, respectively-that are required for tumors to develop. By treating the MCPyV transgenic mice with each chemical carcinogen, we determined how the viral oncogenes contributed to carcinogenesis. We observed that the MCPyV T antigens synergized with the tumor initiator DMBA, but not with the tumor promoter TPA, cause tumors. Therefore, the MCPyV tumor antigens function primarily as tumor promoters, similar to that seen with human papillomavirus (HPV) oncoproteins. These studies provide insight into the role of MCPyV T antigen expression in tumor formation in vivo and contribute to our understanding of how MCPyV may function as a human DNA tumor virus.

Genetic variability of the Avian leukosis virus subgroup J gp85 gene in layer flocks in Lower Egypt.

AIM: This study aimed to determine the prevalence of layer flock tumor disease in Lower Egypt during the period of 2018-2019 and to undertake molecular characterization and determine the genetic diversity of all identified viruses. MATERIALS AND METHODS: Forty samples were collected from layer chicken located in six governorates of Lower Egypt during the period of 2018-2019. Samples were taken from tumors in different organs. Tumor tissues were identified by histopathological sectioning and then further confirmed by a reverse-transcription polymerase chain reaction. Finally, genetic evolution of Avian leukosis virus (ALV-J) gp85 gene was studied. RESULTS: All the study samples were negative for Marek's disease virus, reticuloendotheliosis virus, ALV (A,B,C and D) and 20 samples were positive for ALV-J in backyard in six governrates. Sequencing of ALV-J gp85 gene was performed for six representative samples (one from each governorate), and they were found to be genetically related to prototype virus HPRS-1003 (identity percentage: 91.2-91.8%), but they were from a different group that was similar to the AF88-USA strain (first detected in 2000) with specific mutations, and they differed from a strain that was previously isolated in Egypt in 2005, forming two different subgroups (I and II) that had mutations in the hr1domain (V128F, R136A) and hr2 domain (S197G, E202K). CONCLUSION: The ALV-J virus was the main cause of neoplastic disease in layer chickens from Lower Egypt in the period of 2018-2019. We found that the genetic evolution of ALV-J gp85 gene was related to prototype virus HPRS-1003 but in a different group with a specific mutation. Further studies are needed to evaluate the antigenicity and pathogenicity of recently detected ALV-J strains.

DNA Tumor Viruses and Their Contributions to Molecular Biology.

This summer marks the 51st anniversary of the DNA tumor virus meetings. Scientists from around the world will gather in Trieste, Italy, to report their latest results and to agree or disagree on the current concepts that define our understanding of this diverse class of viruses. This article offers a brief history of the impact the study of these viruses has had on molecular and cancer biology and discusses obstacles and opportunities for future progress.

No evidence for human papillomavirus having a causal role in salivary gland tumors.

BACKGROUND: Salivary gland malignancies are a very heterogeneous group of cancers, with histologically > 20 different subtypes, and prognosis varies greatly. Their etiology is unknown, however, a few small studies show presence of human papillomavirus (HPV) in some subtypes, although the evidence for HPV having a causal role is weak. The aim of this study was to investigate if HPV plays a causal role in the development of different parotid salivary gland tumor subtypes. METHODS: DNA was extracted from 107 parotid salivary gland formalin fixed paraffin embedded tumors and 10 corresponding metastases, and tested for 27 different HPV types using a multiplex bead based assay. HPV DNA positive tumors were stained for p16INK4a overexpression by immunohistochemistry. RESULTS: One of the 107 malignant parotid salivary gland tumors (0.93%) and its corresponding metastasis on the neck were positive for HPV16 DNA, and both also overexpressed p16INK4a. The HPV positive primary tumor was a squamous cell carcinoma; neither mucoepidermoid nor adenoid cystic tumors were found HPV positive. CONCLUSIONS: In conclusion, HPV DNA analysis in a large number of malignant parotid salivary gland tumors, including 12 different subtypes, did not show any strong indications that tested HPV types have a causal role in the studied salivary gland tumor types.

Human Polyomaviruses Are Not Frequently Present in Cancer of the Salivary Glands.

BACKGROUND/AIM: Malignant tumors of the salivary glands are rare and heterogeneous, with more than 20 subtypes, and classified mainly by histopathology. Their diagnosis is often challenging and their etiology unknown. Here, the possible association between human polyomaviruses (PyVs) and one or more salivary gland tumor subtypes was examined. MATERIALS AND METHODS: Ninety-one primary tumors, including 12 subtypes and eight corresponding metastases, were analyzed for the presence of DNA of 10 different human PyV species by a bead-based multiplex assay using polymerase chain reaction and Luminex analyses. RESULTS: Three samples, one adenocarcinoma (not otherwise specified), one adenoid cystic carcinoma, and one mucoepidermoid carcinoma were found to be positive. However, the amount of MCPyV DNA in these tumors was estimated to be less than one genome per tumor cell. CONCLUSION: The analysis of DNA from 10 human PyVs in a large number of malignant salivary gland cancers did not implicate any of these human PyVs as an important causative agent in any of the 12 subtypes studied.

Plasmid Partitioning by Human Tumor Viruses.

The human tumor viruses that replicate as plasmids (we use the term plasmid to avoid any confusion in the term episome, which was coined to mean DNA elements that occur both extrachromosomally and as integrated forms during their life cycles, as does phage lambda) share many features in their DNA synthesis. We know less about their mechanisms of maintenance in proliferating cells, but these mechanisms must underlie their partitioning to daughter cells. One amazing implication of how these viruses are thought to maintain themselves is that while host chromosomes commit themselves to partitioning in mitosis, these tumor viruses would commit themselves to partitioning before mitosis and probably in S phase shortly after their synthesis.

The biological properties of different Epstein-Barr virus strains explain their association with various types of cancers.

The Epstein-Barr virus (EBV) is etiologically associated with the development of multiple types of tumors, but it is unclear whether this diversity is due to infection with different EBV strains. We report a comparative characterization of SNU719, GP202, and YCCEL1, three EBV strains that were isolated from gastric carcinomas, M81, a virus isolated in a nasopharyngeal carcinoma and several well-characterized laboratory type A strains. We found that B95-8, Akata and GP202 induced cell growth more efficiently than YCCEL1, SNU719 and M81 and this correlated positively with the expression levels of the viral BHRF1 miRNAs. In infected B cells, all strains except Akata and B95-8 induced lytic replication, a risk factor for carcinoma development, although less efficiently than M81. The panel of viruses induced tumors in immunocompromised mice with variable speed and efficacy that did not strictly mirror their in vitro characteristics, suggesting that additional parameters play an important role. We found that YCCEL1 and M81 infected primary epithelial cells, gastric carcinoma cells and gastric spheroids more efficiently than Akata or B95-8. Reciprocally, Akata and B95-8 had a stronger tropism for B cells than YCCEL1 or M81. These data suggest that different EBV strains will induce the development of lymphoid tumors with variable efficacy in immunocompromised patients and that there is a parallel between the cell tropism of the viral strains and the lineage of the tumors they induce. Thus, EBV strains can be endowed with properties that will influence their transforming abilities and the type of tumor they induce.

Efficient Transformation of Primary Human Mesenchymal Stromal Cells by Adenovirus Early Region 1 Oncogenes.

Previous observations that human amniotic fluid cells (AFC) can be transformed by human adenovirus type 5 (HAdV-5) E1A/E1B oncogenes prompted us to identify the target cells in the AFC population that are susceptible to transformation. Our results demonstrate that one cell type corresponding to mesenchymal stem/stroma cells (hMSCs) can be reproducibly transformed by HAdV-5 E1A/E1B oncogenes as efficiently as primary rodent cultures. HAdV-5 E1-transformed hMSCs exhibit all properties commonly associated with a high grade of oncogenic transformation, including enhanced cell proliferation, anchorage-independent growth, increased growth rate, and high telomerase activity as well as numerical and structural chromosomal aberrations. These data confirm previous work showing that HAdV preferentially transforms cells of mesenchymal origin in rodents. More importantly, they demonstrate for the first time that human cells with stem cell characteristics can be completely transformed by HAdV oncogenes in tissue culture with high efficiency. Our findings strongly support the hypothesis that undifferentiated progenitor cells or cells with stem cell-like properties are highly susceptible targets for HAdV-mediated cell transformation and suggest that virus-associated tumors in humans may originate, at least in part, from infections of these cell types. We expect that primary hMSCs will replace the primary rodent cultures in HAdV viral transformation studies and are confident that these investigations will continue to uncover general principles of viral oncogenesis that can be extended to human DNA tumor viruses as well. IMPORTANCE: It is generally believed that transformation of primary human cells with HAdV-5 E1 oncogenes is very inefficient. However, a few cell lines have been successfully transformed with HAdV-5 E1A and E1B, indicating that there is a certain cell type which is susceptible to HAdV-mediated transformation. Interestingly, all those cell lines have been derived from human embryonic tissue, albeit the exact cell type is not known yet. We show for the first time the successful transformation of primary human mesenchymal stromal cells (hMSCs) by HAdV-5 E1A and E1B. Further, we show upon HAdV-5 E1A and E1B expression that these primary progenitor cells exhibit features of tumor cells and can no longer be differentiated into the adipogenic, chondrogenic, or osteogenic lineage. Hence, primary hMSCs represent a robust and novel model system to elucidate the underlying molecular mechanisms of adenovirus-mediated transformation of multipotent human progenitor cells.

Genotipificación, niveles de expresión y estado físico del virus del papiloma humano en pacientes colombianos con cáncer de células escamosas en la cavidad oral / Genotyping, levels of expression and physical status of human papilloma virus in oropharyngeal squamous cell carcinoma among Colombian patients

Introducción. Uno de los factores de riesgo del carcinoma de células escamosas en la cavidad oral es la infección por el virus del papiloma humano (HPV), cuyas prevalencias dependen de la región geográfica. Objetivo. Identificar los tipos del virus del papiloma humano más frecuentes en el cáncer de la cavidad bucal, sus niveles de expresión y el estado físico del genoma viral. Materiales y métodos. Se seleccionaron 46 pacientes que asistían a los servicios de cirugía de cabeza y cuello en Bogotá, Manizales y Bucaramanga. El examen histopatológico de las muestras incluidas en el estudio demostró la presencia de carcinoma de células escamosas en la cavidad oral en todas ellas. Se extrajo el ADN para genotipificar el virus y determinar el estado físico de su genoma, y el ARN para determinar los transcritos virales mediante reacción en cadena de la polimerasa en tiempo real. Resultados. La prevalencia del virus del papiloma humano en los tumores fue de 21,74% (n=10) y el tipo viral más frecuente fue el HPV-16 (nueve casos). La expresión viral del HPV-16 fue baja (una de 11 copias) y el estado físico predominante fue el mixto (ocho casos), con prevalencia de la disrupción en el sitio de unión de E1 y E2 (2525 a 3720 nucleótidos). Conclusión. En los pacientes con carcinoma de cavidad oral incluidos en este trabajo, la frecuencia del virus del papiloma humano fue relativamente baja (21,7 %) y el tipo viral más frecuente fue el HPV-16, el cual se encontró en forma mixta y con baja expresión de E7 , lo cual puede ser indicativo de un mal pronóstico para el paciente.

Introduction: One of the risk factors for squamous cell oropharyngeal carcinoma is infection with the human papilloma virus (HPV), with prevalences that vary depending on the geographical region. Objective: To identify the most frequent HPV viral types in oropharyngeal cancer, the levels of expression and the physical condition of the viral genome. Materials and methods: Forty-six patients were included in the study from among those attending head and neck surgical services in the cities of Bogotá, Manizales and Bucaramanga. In the histopathological report all study samples were characterized as oropharyngeal squamous cell carcinoma. DNA extraction was subsequently performed for HPV genotyping and to determine the physical state of the viral genome, as well as RNA to determine viral transcripts using real-time PCR. Results: HPV prevalence in tumors was 21.74% (n=10) and the most common viral type was HPV-16 (nine cases). Viral expression for HPV-16 was low (one of 11 copies) and the predominant physical state of the virus was mixed (eight cases), with disruption observed at the E1 - E2 binding site (2525 - 3720 nucleotides). Conclusion: The prevalence of HPV associated with oropharyngeal carcinoma among the Colombian study population was 21.7%, which is relatively low. The most frequent viral type was HPV-16, found in a mixed form and with low expression of E7 , possibly indicating a poor prognosis for these patients.

Genotyping, levels of expression and physical status of human papilloma virus in oropharyngeal squamous cell carcinoma among Colombian patients.

INTRODUCTION: One of the risk factors for squamous cell oropharyngeal carcinoma is infection with the human papilloma virus (HPV), with prevalences that vary depending on the geographical region.  OBJECTIVE: To identify the most frequent HPV viral types in oropharyngeal cancer, the levels of expression and the physical condition of the viral genome.  MATERIALS AND METHODS: Forty-six patients were included in the study from among those attending head and neck surgical services in the cities of Bogotá, Manizales and Bucaramanga. In the histopathological report all study samples were characterized as oropharyngeal squamous cell carcinoma. DNA extraction was subsequently performed for HPV genotyping and to determine the physical state of the viral genome, as well as RNA to determine viral transcripts using real-time PCR.  RESULTS: HPV prevalence in tumors was 21.74% (n=10) and the most common viral type was HPV-16 (nine cases). Viral expression for HPV-16 was low (one of 11 copies) and the predominant physical state of the virus was mixed (eight cases), with disruption observed at the E1 - E2 binding site (2525 - 3720 nucleotides).  CONCLUSION: The prevalence of HPV associated with oropharyngeal carcinoma among the Colombian study population was 21.7%, which is relatively low. The most frequent viral type was HPV-16, found in a mixed form and with low expression of E7, possibly indicating a poor prognosis for these patients.