A Novel In Vivo Infection Model To Study Papillomavirus-Mediated Disease of the Female Reproductive Tract

Monitoring mouse papillomavirus-associated cancer development using longitudinal Pap smear screening

A substantial percentage of the population remains at risk for cervical cancer due to pre-existing human papillomavirus (HPV) infections, despite prophylactic vaccines. Early diagnosis and treatment are crucial for better disease outcomes. The development of new treatments heavily relies on suitable preclinical model systems. Recently, we established a mouse papillomavirus (MmuPV1) model that is relevant to HPV genital pathogenesis. In the current study, we validated the use of Papanicolaou (Pap) smears, a valuable early diagnostic tool for detecting HPV cervical cancer, to monitor disease progression in the MmuPV1 mouse model. Biweekly cervicovaginal swabs were collected from the MmuPV1-infected mice for viral DNA quantitation and cytology assessment. The Pap smear slides were evaluated for signs of epithelial cell abnormalities using the 2014 Bethesda system criteria. Tissues from the infected mice were harvested at various times post-viral infection for additional histological and virological assays. Over time, increased viral replication was consistent with higher levels of viral DNA, and it coincided with an uptick in epithelial cell abnormalities with higher severity scores noted as early as 10 weeks after viral infection. The cytological results also correlated with the histological evaluation of tissues harvested simultaneously. Both immunocompromised and immunocompetent mice with squamous cell carcinoma (SCC) cytology also developed vaginal SCCs. Notably, samples from the MmuPV1-infected mice exhibited similar cellular abnormalities compared to the corresponding human samples at similar disease stages. Hence, Pap smear screening proves to be an effective tool for the longitudinal monitoring of disease progression in the MmuPV1 mouse model.

IMPORTANCE

Papanicolaou (Pap) smear has saved millions of women's lives as a valuable early screening tool for detecting human papillomavirus (HPV) cervical precancers and cancer. However, more than 200,000 women in the United States alone remain at risk for cervical cancer due to pre-existing HPV infection-induced precancers, as there are currently no effective treatments for HPV-associated precancers and cancers other than invasive procedures including a loop electrosurgical excision procedure (LEEP) to remove abnormal tissues. In the current study, we validated the use of Pap smears to monitor disease progression in our recently established mouse papillomavirus model. To the best of our knowledge, this is the first study that provides compelling evidence of applying Pap smears from cervicovaginal swabs to monitor disease progression in mice. This HPV-relevant cytology assay will enable us to develop and test novel antiviral and anti-tumor therapies using this model to eliminate HPV-associated diseases and cancers.

Deficiency in Ever2 does not increase susceptibility of mice to pathogenesis by the mouse papillomavirus, MmuPV1

Epidermodysplasia verruciformis (EV) is a rare genetic skin disorder that is characterized by the development of papillomavirus-induced skin lesions that can progress to squamous cell carcinoma (SCC). Certain high-risk, cutaneous β-genus human papillomaviruses (β-HPVs), in particular HPV5 and HPV8, are associated with inducing EV in individuals who have a homozygous mutation in one of three genes tied to this disease: EVER1, EVER2, or CIB1. EVER1 and EVER2 are also known as TMC6 and TMC8, respectively. Little is known about the biochemical activities of EVER gene products or their roles in facilitating EV in conjunction with β-HPV infection. To investigate the potential effect of EVER genes on papillomavirus infection, we pursued in vivo infection studies by infecting Ever2-null mice with mouse papillomavirus (MmuPV1). MmuPV1 shares characteristics with β-HPVs including similar genome organization, shared molecular activities of their early, E6 and E7, oncoproteins, the lack of a viral E5 gene, and the capacity to cause skin lesions that can progress to SCC. MmuPV1 infections were conducted both in the presence and absence of UVB irradiation, which is known to increase the risk of MmuPV1-induced pathogenesis. Infection with MmuPV1 induced skin lesions in both wild-type and Ever2-null mice with and without UVB. Many lesions in both genotypes progressed to malignancy, and the disease severity did not differ between Ever2-null and wild-type mice. However, somewhat surprisingly, lesion growth and viral transcription was decreased, and lesion regression was increased in Ever2-null mice compared with wild-type mice. These studies demonstrate that Ever2-null mice infected with MmuPV1 do not exhibit the same phenotype as human EV patients infected with β-HPVs.IMPORTANCEHumans with homozygous mutations in the EVER2 gene develop epidermodysplasia verruciformis (EV), a disease characterized by predisposition to persistent β-genus human papillomavirus (β-HPV) skin infections, which can progress to skin cancer. To investigate how EVER2 confers protection from papillomaviruses, we infected the skin of homozygous Ever2-null mice with mouse papillomavirus MmuPV1. Like in humans with EV, infected Ever2-null mice developed skin lesions that could progress to cancer. Unlike in humans with EV, lesions in these Ever2-null mice grew more slowly and regressed more frequently than in wild-type mice. MmuPV1 transcription was higher in wild-type mice than in Ever2-null mice, indicating that mouse EVER2 does not confer protection from papillomaviruses. These findings suggest that there are functional differences between MmuPV1 and β-HPVs and/or between mouse and human EVER2.

Key aspects of papillomavirus infection influence the host cervicovaginal microbiome in a preclinical murine papillomavirus (MmuPV1) infection model

Human papillomaviruses (HPVs) are the most common sexually transmitted infection in the United States and are a major etiological agent of cancers in the anogenital tract and oral cavity. Growing evidence suggests changes in the host microbiome are associated with the natural history and ultimate outcome of HPV infection. We sought to define changes in the host cervicovaginal microbiome during papillomavirus infection, persistence, and pathogenesis using the murine papillomavirus (MmuPV1) cervicovaginal infection model. Cervicovaginal lavages were performed over a time course of MmuPV1 infection in immunocompetent female FVB/N mice and extracted DNA was analyzed by qPCR to track MmuPV1 viral copy number. 16S ribosomal RNA (rRNA) gene sequencing was used to determine the composition and diversity of microbial communities throughout this time course. We also sought to determine whether specific microbial communities exist across the spectrum of MmuPV1-induced neoplastic disease. We, therefore, performed laser-capture microdissection to isolate regions of disease representing all stages of neoplastic disease progression (normal, low- and high-grade dysplasia, and cancer) from female reproductive tract tissue sections from MmuPV1-infected mice and performed 16S rRNA sequencing. Consistent with other studies, we found that the natural murine cervicovaginal microbiome is highly variable across different experiments. Despite these differences in initial microbiome composition between experiments, we observed that MmuPV1 persistence, viral load, and severity of disease influenced the composition of the cervicovaginal microbiome. These studies demonstrate that papillomavirus infection can alter the cervicovaginal microbiome.IMPORTANCEHuman papillomaviruses (HPVs) are the most common sexually transmitted infection in the United States. A subset of HPVs that infect the anogenital tract (cervix, vagina, anus) and oral cavity cause at least 5% of cancers worldwide. Recent evidence indicates that the community of microbial organisms present in the human cervix and vagina, known as the cervicovaginal microbiome, plays a role in HPV-induced cervical cancer. However, the mechanisms underlying this interplay are not well-defined. In this study, we infected the female reproductive tract of mice with a murine papillomavirus (MmuPV1) and found that key aspects of papillomavirus infection and disease influence the host cervicovaginal microbiome. This is the first study to define changes in the host microbiome associated with MmuPV1 infection in a preclinical animal model of HPV-induced cervical cancer. These results pave the way for using MmuPV1 infection models to further investigate the interactions between papillomaviruses and the host microbiome.

The Larynx is Protected from Secondary and Vertical Papillomavirus Infection in Immunocompetent Mice

OBJECTIVE

Mouse papillomavirus MmuPV1 causes both primary and secondary infections of the larynx in immunocompromised mice. Understanding lateral and vertical transmission of papillomavirus to the larynx would benefit patients with recurrent respiratory papillomatosis (RRP). To test the hypothesis that the larynx is uniquely vulnerable to papillomavirus infection, and to further develop a mouse model of RRP, we assessed whether immunocompetent mice were vulnerable to secondary or vertical laryngeal infection with MmuPV1.

METHODS

Larynges were collected from 405 immunocompetent adult mice that were infected with MmuPV1 in the oropharynx, oral cavity, or anus, and 31 mouse pups born to immunocompetent females infected in the cervicovaginal tract. Larynges were analyzed via polymerase chain reaction (PCR) of lavage fluid or whole tissues for viral DNA, histopathology, and/or in situ hybridization for MmuPV1 transcripts.

RESULTS

Despite some positive laryngeal lavage PCR screens, all laryngeal tissue PCR and histopathology results were negative for MmuPV1 DNA, transcripts, and disease. There was no evidence for lateral spread of MmuPV1 to the larynges of immunocompetent mice that were infected in the oral cavity, oropharynx, or anus. Pups born to infected mothers were negative for laryngeal MmuPV1 infection from birth through weaning age.

CONCLUSION

Secondary and vertical laryngeal MmuPV1 infections were not found in immunocompetent mice. Further work is necessary to explore immunologic control of laryngeal papillomavirus infection in a mouse model and to improve preclinical models of RRP.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:2322-2330, 2024.

MmuPV1 E6 induces cell proliferation and other hallmarks of cancer

IMPORTANCE

The Mus musculus papillomavirus 1 (MmuPV1) E6 and E7 proteins are required for MmuPV1-induced disease. Our understanding of the activities of MmuPV1 E6 has been based on affinity purification/mass spectrometry studies where cellular interacting partners of MmuPV1 E6 were identified, and these studies revealed that MmuPV1 E6 can inhibit keratinocyte differentiation through multiple mechanisms. We report that MmuPV1 E6 encodes additional activities including the induction of proliferation, resistance to density-mediated growth arrest, and decreased dependence on exogenous growth factors. Proteomic and transcriptomic analyses provided evidence that MmuPV1 E6 increases the expression and steady state levels of a number of cellular proteins that promote cellular proliferation and other hallmarks of cancer. These results indicate that MmuPV1 E6 is a major driver of MmuPV1-induced pathogenesis.

Immune Responses in Oral Papillomavirus Clearance in the MmuPV1 Mouse Model

Human papillomavirus (HPV)-induced oropharyngeal cancer now exceeds HPV-induced cervical cancer, with a noticeable sex bias. Although it is well established that women have a more proficient immune system, it remains unclear whether immune control of oral papillomavirus infections differs between sexes. In the current study, we use genetically modified mice to target CCR2 and Stat1 pathways, with the aim of investigating the role of both innate and adaptive immune responses in clearing oral papillomavirus, using our established papillomavirus (MmuPV1) infection model. Persistent oral MmuPV1 infection was detected in Rag1ko mice with T and B cell deficiencies. Meanwhile, other tested mice were susceptible to MmuPV1 infections but were able to clear the virus. We found sex differences in key myeloid cells, including macrophages, neutrophils, and dendritic cells in the infected tongues of wild type and Stat1ko mice but these differences were not observed in CCR2ko mice. Intriguingly, we also observed a sex difference in anti-MmuPV1 E4 antibody levels, especially for two IgG isotypes: IgG2b and IgG3. However, we found comparable numbers of interferon-gamma-producing CD8 T cells stimulated by E6 and E7 in both sexes. These findings suggest that males and females may use different components of innate and adaptive immune responses to control papillomavirus infections in the MmuPV1 mouse model. The observed sex difference in immune responses, especially in myeloid cells including dendritic cell (DC) subsets, may have potential diagnostic and prognostic values for HPV-associated oropharyngeal cancer.

Human papillomaviruses: Knowns, mysteries, and unchartered territories

There has been an explosion in the number of papillomaviruses that have been identified and fully sequenced. Yet only a minute fraction of these has been studied in any detail. Most of our molecular research efforts have focused on the E6 and E7 proteins of "high-risk," cancer-associated human papillomaviruses (HPVs). Interactions of the high-risk HPV E6 and E7 proteins with their respective cellular targets, the p53 and the retinoblastoma tumor suppressors, have been investigated in minute detail. Some have thus questioned if research on papillomaviruses remains an exciting and worthwhile area of investigation. However, fundamentally new insights on the biological activities and cellular targets of the high-risk HPV E6 and E7 proteins have been discovered and previously unstudied HPVs have been newly associated with human diseases. HPV infections continue to be an important cause of human morbidity and mortality and since there are no antivirals to combat HPV infections, research on HPVs should remain attractive to new investigators and biomedical funding agencies, alike.

The antiviral effects of a MEK1/2 inhibitor promote tumor regression in a preclinical model of human papillomavirus infection-induced tumorigenesis

Human papillomaviruses (HPVs) are a significant public health concern due to their widespread transmission, morbidity, and oncogenic potential. Despite efficacious vaccines, millions of unvaccinated individuals and those with existing infections will develop HPV-related diseases for the next two decades and beyond. The continuing burden of HPV-related diseases is exacerbated by the lack of effective therapies or cures for infections, highlighting the need to identify and develop antivirals. The experimental murine papillomavirus type 1 (MmuPV1) model provides opportunities to study papillomavirus pathogenesis in cutaneous epithelium, the oral cavity, and the anogenital tract. However, to date the MmuPV1 infection model has not been used to demonstrate the effectiveness of potential antivirals. We previously reported that inhibitors of cellular MEK/ERK signaling suppress oncogenic HPV early gene expression in three-dimensional tissue cultures. Herein, we adapted the MmuPV1 infection model to determine whether MEK inhibitors have anti-papillomavirus properties in vivo. We demonstrate that oral delivery of a MEK1/2 inhibitor promotes papilloma regression in immunodeficient mice that otherwise would have developed persistent infections. Quantitative histological analyses reveal that inhibition of MEK/ERK signaling reduces E6/E7 mRNA, MmuPV1 DNA, and L1 protein expression within MmuPV1-induced lesions. These data suggest that MEK1/2 signaling is essential for both early and late MmuPV1 replication events supporting our previous findings with oncogenic HPVs. We also provide evidence that MEK inhibitors protect mice from developing secondary tumors. Thus, our data suggest that MEK inhibitors have potent antiviral and anti-tumor properties in a preclinical mouse model and merit further investigation as papillomavirus antiviral therapies.

MmuPV1 E7's interaction with PTPN14 delays Epithelial differentiation and contributes to virus-induced skin disease

Human papillomaviruses (HPVs) contribute to approximately 5% of all human cancers. Species-specific barriers limit the ability to study HPV pathogenesis in animal models. Murine papillomavirus (MmuPV1) provides a powerful tool to study the roles of papillomavirus genes in pathogenesis arising from a natural infection. We previously identified Protein Tyrosine Phosphatase Non-Receptor Type 14 (PTPN14), a tumor suppressor targeted by HPV E7 proteins, as a putative cellular target of MmuPV1 E7. Here, we confirmed the MmuPV1 E7-PTPN14 interaction. Based on the published structure of the HPV18 E7/PTPN14 complex, we generated a MmuPV1 E7 mutant, E7K81S, that was defective for binding PTPN14. Wild-type (WT) and E7K81S mutant viral genomes replicated as extrachromosomal circular DNAs to comparable levels in mouse keratinocytes. E7K81S mutant virus (E7K81S MmuPV1) was generated and used to infect FoxN/Nude mice. E7K81S MmuPV1 caused neoplastic lesions at a frequency similar to that of WT MmuPV1, but the lesions arose later and were smaller than WT-induced lesions. The E7K81S MmuPV1-induced lesions also had a trend towards a less severe grade of neoplastic disease. In the lesions, E7K81S MmuPV1 supported the late (productive) stage of the viral life cycle and promoted E2F activity and cellular DNA synthesis in suprabasal epithelial cells to similar degrees as WT MmuPV1. There was a similar frequency of lateral spread of infections among mice infected with E7K81S or WT MmuPV1. Compared to WT MmuPV1-induced lesions, E7K81S MmuPV1-induced lesions had a significant expansion of cells expressing differentiation markers, Keratin 10 and Involucrin. We conclude that an intact PTPN14 binding site is necessary for MmuPV1 E7's ability to contribute to papillomavirus-induced pathogenesis and this correlates with MmuPV1 E7 causing a delay in epithelial differentiation, which is a hallmark of papillomavirus-induced neoplasia.

Stress keratin 17 and estrogen support viral persistence and modulate the immune environment during cervicovaginal murine papillomavirus infection

A murine papillomavirus, MmuPV1, infects both cutaneous and mucosal epithelia of laboratory mice and can be used to model high-risk human papillomavirus (HPV) infection and HPV-associated disease. We have shown that estrogen exacerbates papillomavirus-induced cervical disease in HPV-transgenic mice. We have also previously identified stress keratin 17 (K17) as a host factor that supports MmuPV1-induced cutaneous disease. Here, we sought to test the role of estrogen and K17 in MmuPV1 infection and associated disease in the female reproductive tract. We experimentally infected wild-type and K17 knockout (K17KO) mice with MmuPV1 in the female reproductive tract in the presence or absence of exogenous estrogen for 6 mon. We observed that a significantly higher percentage of K17KO mice cleared the virus as opposed to wild-type mice. In estrogen-treated wild-type mice, the MmuPV1 viral copy number was significantly higher compared to untreated mice by as early as 2 wk postinfection, suggesting that estrogen may help facilitate MmuPV1 infection and/or establishment. Consistent with this, viral clearance was not observed in either wild-type or K17KO mice when treated with estrogen. Furthermore, neoplastic disease progression and cervical carcinogenesis were supported by the presence of K17 and exacerbated by estrogen treatment. Subsequent analyses indicated that estrogen treatment induces a systemic immunosuppressive state in MmuPV1-infected animals and that both estrogen and K17 modulate the local intratumoral immune microenvironment within MmuPV1-induced neoplastic lesions. Collectively, these findings suggest that estrogen and K17 act at multiple stages of papillomavirus-induced disease at least in part via immunomodulatory mechanisms.

3D engineered tissue models for studying human-specific infectious viral diseases

Viral infections cause damage to various organ systems by inducing organ-specific symptoms or systemic multi-organ damage. Depending on the infection route and virus type, infectious diseases are classified as respiratory, nervous, immune, digestive, or skin infections. Since these infectious diseases can widely spread in the community and their catastrophic effects are severe, identification of their causative agent and mechanisms underlying their pathogenesis is an urgent necessity. Although infection-associated mechanisms have been studied in two-dimensional (2D) cell culture models and animal models, they have shown limitations in organ-specific or human-associated pathogenesis, and the development of a human-organ-mimetic system is required. Recently, three-dimensional (3D) engineered tissue models, which can present human organ-like physiology in terms of the 3D structure, utilization of human-originated cells, recapitulation of physiological stimuli, and tight cell–cell interactions, were developed. Furthermore, recent studies have shown that these models can recapitulate infection-associated pathologies. In this review, we summarized the recent advances in 3D engineered tissue models that mimic organ-specific viral infections. First, we briefly described the limitations of the current 2D and animal models in recapitulating human-specific viral infection pathology. Next, we provided an overview of recently reported viral infection models, focusing particularly on organ-specific infection pathologies. Finally, a future perspective that must be pursued to reconstitute more human-specific infectious diseases is presented.

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3D in vitro models are different from the traditional model in the infection process.

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Human-specific infection research requires a 3D microenvironment and human cells.

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3D in vitro infectious models can be useful for basic research on infectious disease.

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3D in vitro infectious models recapitulate the complex cell-virus-immune interaction.

The lifestyle factors of physical activity and diet balance associated with HPV infection in China: The cross-sectional study

Background

Human wellbeing has been linked with lifestyle factors such as physical activity, diet balance, sleep quality, depression, and anxiety. However, few studies illustrate the relationship between such lifestyle factors and HPV infection. In this study, we investigated the association between lifestyle factors, age, disease status and HPV infection.

Participants and methods

Participants were recruited through a digital eHealth platform in Shenzhen, Mainland China. Both lifestyle factors and cervicovaginal mucus (CVM) samples to test for HPV outcomes were collected from each participant as a cross-sectional study. In addition, the eHealth platform recorded age and current or history diseases, which were adjusted to apply for both univariable and multivariable logistic regression. Furthermore, lifestyle factors were categorized as different levels to conduct stratification analysis.

Results

We recruited 149 HPV positive and 346 HPV negative participants through HPV detection. Physical activity and diet balance were significantly associated with HPV infection in lifestyle factors (P values < 0.001) after adjusting for age and current or history diseases. However, stratified analysis showed three factors were insignificant for HPV infection - namely, sleep quality, depression, and anxiety. Most HPV infections involved a sole HPV serotype (83%), and diet balance was the most significant difference between sole and multiple HPV infections.

Conclusions

Among lifestyle factors, physical inactivity or diet imbalance can significantly increase HPV infection risk. In particular, diet balance might be related to the number of HPV serotypes. Our results suggest that exercising and regulating diet may reduce the risk of HPV infection.

The use of a topical protease inhibitor, Saquinavir, to alleviate mouse papillomavirus-mediated anal disease

Select protease inhibitors (PI) have been found to be effective in decreasing human papillomavirus oncoprotein expression. This study evaluated whether the topical PI, Saquinavir (SQV), promotes viral clearance in an infectious mouse model with Mus musculus papillomavirus 1 (MmuPV1). NOD scid gamma (NSG) mice were anally infected with ∼4 × 10⁸ viral genome equivalents of MmuPV1 and 120 days post-infection (when majority have high-grade anal dysplasia), began topical treatments: control (mock), 7,12-dimethylbenz(a)anthracene (DMBA) only, once weekly to promote carcinogenesis, 1% SQV only, daily (Monday - Friday), and SQV + DMBA. Viral MmuPV1 load was analyzed from anal lavages pre and post-treatment. Anal tissue was harvested, processed, and evaluated for drug absorption, grade of anal disease, and anal viral RNA. Results suggest that topical SQV promotes decreased viral shedding in female mice treated with SQV.

Molecular Mechanisms of MmuPV1 E6 and E7 and Implications for Human Disease

Human papillomaviruses (HPVs) cause a substantial amount of human disease from benign disease such as warts to malignant cancers including cervical carcinoma, head and neck cancer, and non-melanoma skin cancer. Our ability to model HPV-induced malignant disease has been impeded by species specific barriers and pre-clinical animal models have been challenging to develop. The recent discovery of a murine papillomavirus, MmuPV1, that infects laboratory mice and causes the same range of malignancies caused by HPVs provides the papillomavirus field the opportunity to test mechanistic hypotheses in a genetically manipulatable laboratory animal species in the context of natural infections. The E6 and E7 proteins encoded by high-risk HPVs, which are the HPV genotypes associated with human cancers, are multifunctional proteins that contribute to HPV-induced cancers in multiple ways. In this review, we describe the known activities of the MmuPV1-encoded E6 and E7 proteins and how those activities relate to the activities of HPV E6 and E7 oncoproteins encoded by mucosal and cutaneous high-risk HPV genotypes.

Passive Immunization with a Single Monoclonal Neutralizing Antibody Protects against Cutaneous and Mucosal Mouse Papillomavirus Infections

We have established a mouse papillomavirus (MmuPV1) model that induces both cutaneous and mucosal infections and cancers. In the current study, we use this model to test our hypothesis that passive immunization using a single neutralizing monoclonal antibody can protect both cutaneous and mucosal sites at different time points after viral inoculation. We conducted a series of experiments involving the administration of either a neutralizing monoclonal antibody, MPV.A4, or control monoclonal antibodies to both outbred and inbred athymic mice. Three clinically relevant mucosal sites (lower genital tract for females and anus and tongue for both males and females) and two cutaneous sites (muzzle and tail) were tested. At the termination of the experiments, all tested tissues were harvested for virological analyses. Significantly lower levels of viral signals were detected in the MPV.A4-treated female mice up to 6 h post-viral inoculation compared to those in the isotype control. Interestingly, males displayed partial protection when they received MPV.A4 at the time of viral inoculation, even though they were completely protected when receiving MPV.A4 at 24 h before viral inoculation. We detected MPV.A4 in the blood starting at 1 h and up to 8 weeks postadministration in some mice. Parallel to these in vivo studies, we conducted in vitro neutralization using a mouse keratinocyte cell line and observed complete neutralization up to 8 h post-viral inoculation. Thus, passive immunization with a monoclonal neutralizing antibody can protect against papillomavirus infection at both cutaneous and mucosal sites and is time dependent. IMPORTANCE This is the first study testing a single monoclonal neutralizing antibody (MPV.A4) by passive immunization against papillomavirus infections at both cutaneous and mucosal sites in the same host in the mouse papillomavirus model. We demonstrated that MPV.A4 administered before viral inoculation can protect both male and female athymic mice against MmuPV1 infections at cutaneous and mucosal sites. MPV.A4 also offers partial protection at 6 h post-viral inoculation in female mice. MPV.A4 can be detected in the blood from 1 h to 8 weeks after intraperitoneal (i.p.) injection. Interestingly, males were only partially protected when they received MPV.A4 at the time of viral inoculation. The failed protection in males was due to the absence of neutralizing MPV.A4 at the infected sites. Our findings suggest passive immunization with a single monoclonal neutralizing antibody can protect against diverse papillomavirus infections in a time-dependent manner in mice.

Efficacy of Topically Administered Dihydroartemisinin in Treating Papillomavirus-Induced Anogenital Dysplasia in Preclinical Mouse Models

The artemisinin family of compounds is cytopathic in certain cancer cell lines that are positive for human papillomaviruses (HPV) and can potentially drive the regression of dysplastic lesions. We evaluated the efficacy of topical dihydroartemisinin (DHA) on cervical dysplasia and anal dysplasia in two papillomavirus mouse models: K14E6/E7 transgenic mice, which express HPV16 oncogenes; and immunodeficient NOD/SCID gamma (NSG) mice infected with Mus musculus papillomavirus (MmuPV1). Mice started treatment with DHA at 25 weeks of age (K14E6/E7) or 20 weeks post infection (MmuPV1-infected), when the majority of mice are known to have papillomavirus-induced low- to high-grade dysplasia. Mice were treated with or without topical DHA at the cervix or anus and with or without topical treatment with the chemical carcinogen 7,12 dimethylbenz(a)anthracene (DMBA) at the anus of in transgenic mice to induce neoplastic progression. Mice were monitored for overt tumor growth, and tissue was harvested after 20 weeks of treatment and scored for severity of histological disease. For MmuPV1-infected mice, anogenital lavages were taken to monitor for viral clearance. Tissues were also evaluated for viral gene expression at the RNA and/or protein levels. Treatment with topical DHA did not reduce dysplasia in the anogenital tract in either papillomavirus-induced mouse model and did not prevent progression to anal cancer in the DMBA-treated K14E6/E7 mice.

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.

Expanded Basal Compartment and Disrupted Barrier in Vocal Fold Epithelium Infected with Mouse Papillomavirus MmuPV1

Laryngeal infection with low-risk human papillomaviruses can cause recurrent respiratory papillomatosis (RRP), a disease with severe effects on vocal fold epithelium resulting in impaired voice function and communication. RRP research has been stymied by limited preclinical models. We recently reported a murine model of laryngeal MmuPV1 infection and disease in immunodeficient mice. In the current study, we compare quantitative and qualitative measures of epithelial proliferation, apoptosis, differentiation, and barrier between mice with MmuPV1-induced disease of the larynx and surrounding tissues and equal numbers of uninfected controls. Findings supported our hypothesis that laryngeal MmuPV1 infection recapitulates many features of RRP. Like RRP, MmuPV1 increased proliferation in infected vocal fold epithelium, expanded the basal compartment of cells, decreased differentiated cells, and altered cell–cell junctions and basement membrane. Effects of MmuPV1 on apoptosis were equivocal, as with RRP. Barrier markers resembled human neoplastic disease in severe MmuPV1-induced disease. We conclude that MmuPV1 infection of the mouse larynx provides a useful, if imperfect, preclinical model for RRP that will facilitate further study and treatment development for this intractable and devastating disease.

A Novel In Vivo Model of Laryngeal Papillomavirus-Associated Disease Using Mus musculus Papillomavirus

Recurrent respiratory papillomatosis (RRP), caused by laryngeal infection with low-risk human papillomaviruses, has devastating effects on vocal communication and quality of life. Factors in RRP onset, other than viral presence in the airway, are poorly understood. RRP research has been stalled by limited preclinical models. The only known papillomavirus able to infect laboratory mice, Mus musculus papillomavirus (MmuPV1), induces disease in a variety of tissues. We hypothesized that MmuPV1 could infect the larynx as a foundation for a preclinical model of RRP. We further hypothesized that epithelial injury would enhance the ability of MmuPV1 to cause laryngeal disease, because injury is a potential factor in RRP and promotes MmuPV1 infection in other tissues. In this report, we infected larynges of NOD scid gamma mice with MmuPV1 with and without vocal fold abrasion and measured infection and disease pathogenesis over 12 weeks. Laryngeal disease incidence and severity increased earlier in mice that underwent injury in addition to infection. However, laryngeal disease emerged in all infected mice by week 12, with or without injury. Secondary laryngeal infections and disease arose in nude mice after MmuPV1 skin infections, confirming that experimentally induced injury is dispensable for laryngeal MmuPV1 infection and disease in immunocompromised mice. Unlike RRP, lesions were relatively flat dysplasias and they could progress to cancer. Similar to RRP, MmuPV1 transcript was detected in all laryngeal disease and in clinically normal larynges. MmuPV1 capsid protein was largely absent from the larynx, but productive infection arose in a case of squamous metaplasia at the level of the cricoid cartilage. Similar to RRP, disease spread beyond the larynx to the trachea and bronchi. This first report of laryngeal MmuPV1 infection provides a foundation for a preclinical model of RRP.

Depo Medroxyprogesterone (DMPA) Promotes Papillomavirus Infections but Does Not Accelerate Disease Progression in the Anogenital Tract of a Mouse Model

Contraceptives such as Depo-medroxyprogesterone (DMPA) are used by an estimated 34 million women worldwide. DMPA has been associated with increased risk of several viral infections including Herpes simplex virus-2 (HSV-2) and Human immunodeficiency virus (HIV). In the current study, we used the mouse papillomavirus (MmuPV1) anogenital infection model to test two hypotheses: (1) contraceptives such as DMPA increase the susceptibility of the anogenital tract to viral infection and (2) long-term contraceptive administration induces more advanced disease at the anogenital tract. DMPA treatments of both athymic nude mice and heterozygous NU/J (Foxn1nu/+) but ovariectomized mice led to a significantly increased viral load at the anogenital tract, suggesting that endogenous sex hormones were involved in increased viral susceptibility by DMPA treatment. Consistent with previous reports, DMPA treatment suppressed host anti-viral activities at the lower genital tract. To test the impact of long-term contraceptive treatment on the MmuPV1-infected lower genital tract, we included two other treatments in addition to DMPA: 17β-estradiol and a non-hormone based contraceptive Cilostazol (CLZ, Pletal). Viral infections were monitored monthly up to nine months post infection by qPCR. The infected vaginal and anal tissues were harvested and further examined by histological, virological, and immunological analyses. Surprisingly, we did not detect a significantly higher grade of histology in animals in the long-term DMPA and 17β-estradiol treated groups when compared to the control groups in the athymic mice we tested. Therefore, although DMPA promotes initial papillomavirus infections in the lower genital tract, the chronic administration of DMPA does not promote cancer development in the infected tissues in our mouse model.

Spontaneous expression of the gene of KI67 and P53 in cynomolgus monkeys infected with papillomavirus

Background and Aim: Cynomolgus monkeys (Macaca fascicularis) develop spontaneous infection of Papillomavirus (PV); thus, potentially beneficial for modeling human PV (HPV) infection study. Contrary to human origin, infection in cynomolgus monkeys does not always show evident clinical symptoms of cervical cancer. The absence of cervical cancer clinical symptoms leads us to investigate the molecular mechanism of the HPV infection in cynomolgus monkeys. This study aimed to investigate the messenger ribonucleic acid (mRNA) expression levels of KI67 and P53 genes, majorly known as biomarker oncogenesis of PV infection. Materials and Methods: The polymerase chain reaction (PCR) technique was used with MY11/MY09 primer to screen PV in cynomolgus monkey, further grouped as positive-PV and negative-PV infection groups. Real-time quantitative PCR was also applied to quantify the mRNA expression levels of KI67 and P53 genes in animals. Results: Increased expression of mRNA level of KI67 genes was significantly higher in Positive- PV group than negative-PV group. In contrast, the P53 mRNA expression level increased markedly higher in the negative-PV group than in the positive-PV group. Conclusion: Our study describes the potential of cynomolgus monkeys as a spontaneous oncogenesis model of PV infection-type. However, we used a limited number of cancer genetic markers. So, further study of other genetic markers is required to prove that cervical cancer could be developed naturally in cynomolgus monkeys.

Role of E6 in Maintaining the Basal Cell Reservoir during Productive Papillomavirus Infection

Papillomaviruses exclusively infect stratified epithelial tissues and cause chronic infections. To achieve this, infected cells must remain in the epithelial basal layer alongside their uninfected neighbors for years or even decades. To examine how papillomaviruses achieve this, we used the in vivo MmuPV1 (Mus musculus papillomavirus 1) model of lesion formation and persistence. During early lesion formation, an increased cell density in the basal layer, as well as a delay in the infected cells' commitment to differentiation, was apparent in cells expressing MmuPV1 E6/E7 RNA. Using cell culture models, keratinocytes exogenously expressing MmuPV1 E6, but not E7, recapitulated this delay in differentiation postconfluence and also grew to a significantly higher density. Cell competition assays further showed that MmuPV1 E6 expression led to a preferential persistence of the cell in the first layer, with control cells accumulating almost exclusively in the second layer. Interestingly, the disruption of MmuPV1 E6 binding to MAML1 protein abrogated these phenotypes. This suggests that the interaction between MAML1 and E6 is necessary for the lower (basal)-layer persistence of MmuPV1 E6-expressing cells. Our results indicate a role for E6 in lesion establishment by facilitating the persistence of infected cells in the epithelial basal layer, a mechanism that is most likely shared by other papillomavirus types. Interruption of this interaction is predicted to impede persistent papillomavirus infection and consequently provides a novel treatment target. IMPORTANCE Persistent infection with high-risk HPV types can lead to development of HPV-associated cancers, and persistent low-risk HPV infection causes problematic diseases, such as recurrent respiratory papillomatosis. The management and treatment of these conditions pose a considerable economic burden. Maintaining a reservoir of infected cells in the basal layer of the epithelium is critical for the persistence of infection in the host, and our studies using the mouse papillomavirus model suggest that E6 gene expression leads to the preferential persistence of epithelial cells in the lower layers during stratification. The E6 interaction with MAML1, a component of the Notch pathway, is required for this phenotype and is linked to E6 effects on cell density and differentiation. These observations are likely to reflect a common E6 role that is preserved among papillomaviruses and provide us with a novel therapeutic target for the treatment of recalcitrant lesions.

Molecular Pathology of Human Papilloma Virus-Negative Cervical Cancers

Cervical cancer is the fourth most common cancer in women worldwide and is predominantly caused by infection with human papillomavirus (HPV). However, a small subset of cervical cancers tests negative for HPV, including true HPV-independent cancers and false-negative cases. True HPV-negative cancers appear to be more prevalent in certain pathological adenocarcinoma subtypes, such as gastric- and clear-cell-type adenocarcinomas. Moreover, HPV-negative cervical cancers have proven to be a biologically distinct tumor subset that follows a different pathogenetic pathway to HPV-associated cervical cancers. HPV-negative cervical cancers are often diagnosed at an advanced stage with a poor prognosis and are expected to persist in the post-HPV vaccination era; therefore, it is important to understand HPV-negative cancers. In this review, we provide a concise overview of the molecular pathology of HPV-negative cervical cancers, with a focus on their definitions, the potential causes of false-negative HPV tests, and the histology, genetic profiles, and pathogenesis of HPV-negative cancers.

The Mouse Papillomavirus Epigenetic Signature Is Characterised by DNA Hypermethylation after Lesion Regression

Papillomaviruses (PVs) are double-stranded DNA tumour viruses that can infect cutaneous and mucosal epidermis. Human papillomavirus (HPV) types have been linked to the causality of cutaneous squamous cell carcinoma (cSCC); however, HPV DNA is not always detected in the resultant tumour. DNA methylation is an epigenetic change that can contribute to carcinogenesis. We hypothesise that the DNA methylation pattern in cells is altered following PV infection. We tested if DNA methylation was altered by PV infection in the mouse papillomavirus (MmuPV1) model. Immunosuppressed mice were infected with MmuPV1 on cutaneous tail skin. Immunosuppression was withdrawn for some mice, causing lesions to spontaneously regress. Reduced representation bisulphite sequencing was carried out on DNA from the actively infected lesions, visibly regressed lesions, and mock-infected control mice. DNA methylation libraries were generated and analysed for differentially methylated regions throughout the genome. The presence of MmuPV1 sequences was also assessed. We identified 834 predominantly differentially hypermethylated fragments in regressed lesions, and no methylation differences in actively infected lesions. The promoter regions of genes associated with tumorigenicity, including the tumour suppressor protein DAPK1 and mismatch repair proteins MSH6 and PAPD7, were hypermethylated. Viral DNA was detected in active lesions and in some lesions that had regressed. This is the first description of the genome-wide DNA methylation landscape for active and regressed MmuPV1 lesions. We propose that the DNA hypermethylation in the regressed lesions that we report here may increase the susceptibility of cells to ultraviolet-induced cSCC.

Host defence and persistent human papillomavirus infection

The ability to establish long term persistent infection is a feature of human papillomaviruses. The available evidence is that this ability is a consequence of a complex local immune milieu whereby innate immune receptors and signalling pathway cascades are inhibited by HPV early proteins resulting in failure of dendritic cell maturation, antigen processing and presentation and activation of cytotoxic antigen specific T cell responses. The development of cutaneous and mucosal infection models with the mouse papillomavirus MmuPV1 and the access to multiple gene deficient strains is providing the frame work to dissect the mechanisms underlying these complex host virus interactions.

Human papillomaviruses: diversity, infection and host interactions

Human papillomaviruses (HPVs) are an ancient and highly successful group of viruses that have co-evolved with their host to replicate in specific anatomical niches of the stratified epithelia. They replicate persistently in dividing cells, hijack key host cellular processes to manipulate the cellular environment and escape immune detection, and produce virions in terminally differentiated cells that are shed from the host. Some HPVs cause benign, proliferative lesions on the skin and mucosa, and others are associated with the development of cancer. However, most HPVs cause infections that are asymptomatic and inapparent unless the immune system becomes compromised. To date, the genomes of almost 450 distinct HPV types have been isolated and sequenced. In this Review, I explore the diversity, evolution, infectious cycle, host interactions and disease association of HPVs.

Mouse Papillomavirus L1 and L2 Are Dispensable for Viral Infection and Persistence at Both Cutaneous and Mucosal Tissues

Papillomavirus L1 and L2, the major and minor capsid proteins, play significant roles in viral assembly, entry, and propagation. In the current study, we investigate the impact of L1 and L2 on viral life cycle and tumor growth with a newly established mouse papillomavirus (MmuPV1) infection model. MmuPV1 L1 knockout, L2 knockout, and L1 plus L2 knockout mutant genomes (designated as L1ATGko-4m, L2ATGko, and L1-L2ATGko respectively) were generated. The mutants were examined for their ability to generate lesions in athymic nude mice. Viral activities were examined by qPCR, immunohistochemistry (IHC), in situ hybridization (ISH), and transmission electron microscopy (TEM) analyses. We demonstrated that viral DNA replication and tumor growth occurred at both cutaneous and mucosal sites infected with each of the mutants. Infections involving L1ATGko-4m, L2ATGko, and L1-L2ATGko mutant genomes generally resulted in smaller tumor sizes compared to infection with the wild type. The L1 protein was absent in L1ATGko-4m and L1-L2ATGko mutant-treated tissues, even though viral transcripts and E4 protein expression were robust. Therefore, L1 is not essential for MmuPV1-induced tumor growth, and this finding parallels our previous observations in the rabbit papillomavirus model. Very few viral particles were detected in L2ATGko mutant-infected tissues. Interestingly, the localization of L1 in lesions induced by L2ATGko was primarily cytoplasmic rather than nuclear. The findings support the hypothesis that the L2 gene influences the expression, location, transport, and assembly of the L1 protein in vivo.

The Mus musculus Papillomavirus Type 1 E7 Protein Binds to the Retinoblastoma Tumor Suppressor: Implications for Viral Pathogenesis

The species specificity of papillomaviruses has been a significant roadblock for performing in vivo pathogenesis studies in common model organisms. The Mus musculus papillomavirus type 1 (MmuPV1) causes cutaneous papillomas that can progress to squamous cell carcinomas in laboratory mice. The papillomavirus E6 and E7 genes encode proteins that establish and maintain a cellular milieu that allows for viral genome synthesis and viral progeny synthesis in growth-arrested, terminally differentiated keratinocytes. The E6 and E7 proteins provide this activity by binding to and functionally reprogramming key cellular regulatory proteins. The MmuPV1 E7 protein lacks the canonical LXCXE motif that mediates the binding of multiple viral oncoproteins to the cellular retinoblastoma tumor suppressor protein, RB1. Our proteomic experiments, however, revealed that MmuPV1 E7 still interacts with RB1. We show that MmuPV1 E7 interacts through its C terminus with the C-terminal domain of RB1. Binding of MmuPV1 E7 to RB1 did not cause significant activation of E2F-regulated cellular genes. MmuPV1 E7 expression was shown to be essential for papilloma formation. Experimental infection of mice with MmuPV1 expressing an E7 mutant that is defective for binding to RB1 caused delayed onset, lower incidence, and smaller sizes of papillomas. Our results demonstrate that the MmuPV1 E7 gene is essential and that targeting noncanonical activities of RB1, which are independent of RB1's ability to modulate the expression of E2F-regulated genes, contribute to papillomavirus-mediated pathogenesis. IMPORTANCE Papillomavirus infections cause a variety of epithelial hyperplastic lesions, or warts. While most warts are benign, some papillomaviruses cause lesions that can progress to squamous cell carcinomas, and approximately 5% of all human cancers are caused by human papillomavirus (HPV) infections. The papillomavirus E6 and E7 proteins are thought to function to reprogram host epithelial cells to enable viral genome replication in terminally differentiated, normally growth-arrested cells. E6 and E7 lack enzymatic activities and function by interacting and functionally altering host cell regulatory proteins. Many cellular proteins that can interact with E6 and E7 have been identified, but the biological relevance of these interactions for viral pathogenesis has not been determined. This is because papillomaviruses are species specific and do not infect heterologous hosts. Here, we use a recently established mouse papillomavirus (MmuPV1) model to investigate the role of the E7 protein in viral pathogenesis. We show that MmuPV1 E7 is necessary for papilloma formation. The retinoblastoma tumor suppressor protein (RB1) is targeted by many papillomaviral E7 proteins, including cancer-associated HPVs. We show that MmuPV1 E7 can bind RB1 and that infection with a mutant MmuPV1 virus that expresses an RB1 binding-defective E7 mutant caused smaller and fewer papillomas that arise with delayed kinetics.

Role of IQGAP1 in Carcinogenesis

Scaffolding proteins can play important roles in cell signaling transduction. IQ motif-containing GTPase-activating protein 1 (IQGAP1) influences many cellular activities by scaffolding multiple key signaling pathways, including ones involved in carcinogenesis. Two decades of studies provide evidence that IQGAP1 plays an essential role in promoting cancer development. IQGAP1 is overexpressed in many types of cancer, and its overexpression in cancer is associated with lower survival of the cancer patient. Here, we provide a comprehensive review of the literature regarding the oncogenic roles of IQGAP1. We start by describing the major cancer-related signaling pathways scaffolded by IQGAP1 and their associated cellular activities. We then describe clinical and molecular evidence for the contribution of IQGAP1 in different types of cancers. In the end, we review recent evidence implicating IQGAP1 in tumor-related immune responses. Given the critical role of IQGAP1 in carcinoma development, anti-tumor therapies targeting IQGAP1 or its associated signaling pathways could be beneficial for patients with many types of cancer.

Mouse papillomavirus type 1 (MmuPV1) DNA is frequently integrated in benign tumors by microhomology-mediated end-joining

MmuPV1 is a useful model for studying papillomavirus-induced tumorigenesis. We used RNA-seq to look for chimeric RNAs that map to both MmuPV1 and host genomes. In tumor tissues, a higher proportion of total viral reads were virus-host chimeric junction reads (CJRs) (1.9‰ - 7‰) than in tumor-free tissues (0.6‰ - 1.3‰): most CJRs mapped to the viral E2/E4 region. Although most of the MmuPV1 integration sites were mapped to intergenic regions and introns throughout the mouse genome, integrations were seen more than once in several genes: Malat1, Krt1, Krt10, Fabp5, Pard3, and Grip1; these data were confirmed by rapid amplification of cDNA ends (RACE)-Single Molecule Real-Time (SMRT)-seq or targeted DNA-seq. Microhomology sequences were frequently seen at host-virus DNA junctions. MmuPV1 infection and integration affected the expression of host genes. We found that factors for DNA double-stranded break repair and microhomology-mediated end-joining (MMEJ), such as H2ax, Fen1, DNA polymerase Polθ, Cdk1, and Plk1, exhibited a step-wise increase and Mdc1 a decrease in expression in MmuPV1-infected tissues and MmuPV1 tumors relative to normal tissues. Increased expression of mitotic kinases CDK1 and PLK1 appears to be correlated with CtIP phosphorylation in MmuPV1 tumors, suggesting a role for MMEJ-mediated DNA joining in the MmuPV1 integration events that are associated with MmuPV1-induced progression of tumors.

Persistent high-risk HPV infection leads viral DNA integration into the host genome and promotes viral carcinogenesis. We have been using the MmuPV1 mouse-infection model to study papillomavirus tumorigenesis and asked whether MmuPV1 DNA also integrates into the genomes of infected mouse cells. Strikingly, we found that MmuPV1 integration into the infected host genome, like high-risk HPV infections, is very common and the mapped integration sites were distributed on all of the mouse chromosomes. Consistently, we identified microhomology sequences in the range of 2–10 nts always at the integration junction regions. We further verified the MMEJ-mediated viral DNA integration in tumor tissues during MmuPV1 infection and a step-wise increase in the expression of the DNA repair MMEJ host factors from normal tissues, to tumor-free MmuPV1 infected tissues, and then to MmuPV1 tumors. Our observations provide the first evidence of MmuPV1 integration in virus-infected cells and a conceptual advance of how papillomavirus DNA integration contributes to the development of papillomavirus-associated precancers to cancers.

A Novel Model for Papillomavirus-Mediated Anal Disease and Cancer Using the Mouse Papillomavirus

Up to 95% of all anal cancers are associated with infection by human papillomavirus (HPV); however, no established preclinical model exists for high-grade anal disease and cancer mediated by a natural papillomavirus infection. To establish an infection-mediated model, we infected both immunocompromised NSG and immunocompetent FVB/NJ mice with the recently discovered murine papillomavirus MmuPV1, with and without the additional cofactors of UV B radiation (UVB) and/or the chemical carcinogen 7,12-dimethylbenz(a)anthracene (DMBA). Infections were tracked via lavages and swabs for MmuPV1 DNA, and pathology was assessed at the endpoint. Tissues were analyzed for biomarkers of viral infection and papillomavirus-mediated disease, and the localization of viral infection was investigated using biomarkers to characterize the anal microanatomical zones.

Functional roles of female sex hormones and their nuclear receptors in cervical cancer

There has been little progress for several decades in modalities to treat cervical cancer. While the cervix is a hormone-sensitive tissue, physiologic roles of estrogen receptor α (ERα), progesterone receptor (PR), and their ligands in this tissue are poorly understood. It has hampered critical assessments of data in early epidemiologic and clinical studies for cervical cancer. Experimental evidence obtained from studies using mouse models has provided new insights into the molecular mechanism of ERα and PR in cervical cancer. In a mouse model expressing human papillomavirus (HPV) oncogenes, exogenous estrogen promotes cervical cancer through stromal ERα. In the same mouse model, genetic ablation of PR promotes cervical carcinogenesis without exogenous estrogen. Medroxyprogesterone acetate, a PR-activating drug, regresses cervical cancer in the mouse model. These results support that ERα and PR play opposite roles in cervical cancer. They further support that ERα inhibition and PR activation may be translated into valuable treatment for a subset of cervical cancers.

Role of IQGAP1 in Papillomavirus-Associated Head and Neck Tumorigenesis

Approximately 25% of head and neck squamous cell carcinomas (HNSCC) are associated with human papillomavirus (HPV) infection. In these cancers as well as in HPV-associated anogenital cancers, PI3K signaling is highly activated. We previously showed that IQ motif-containing GTPase activating protein 1 (IQGAP1), a PI3K pathway scaffolding protein, is overexpressed in and contributes to HNSCC and that blocking IQGAP1-mediated PI3K signaling reduces HPV-positive HNSCC cell survival and migration. In this study, we tested whether IQGAP1 promotes papillomavirus (PV)-associated HNSCCs. IQGAP1 was necessary for optimal PI3K signaling induced by HPV16 oncoproteins in transgenic mice and MmuPV1 infection, a mouse papillomavirus that causes HNSCC in mice. Furthermore, we found that, at 6 months post-infection, MmuPV1-infected Iqgap1-/- mice developed significantly less severe tumor phenotypes than MmuPV1-infected Iqgap1+/+ mice, indicating a role of IQGAP1 in MmuPV1-associated HNSCC. The tumors resulting from MmuPV1 infection showed features consistent with HPV infection and HPV-associated cancer. However, such IQGAP1-dependent effects on disease severity were not observed in an HPV16 transgenic mouse model for HNC. This may reflect that IQGAP1 plays a role in earlier stages of viral pathogenesis, or other activities of HPV16 oncogenes are more dominant in driving carcinogenesis than their influence on PI3K signaling.

The environmental pollutant and tobacco smoke constituent dibenzo[def,p]chrysene is a co-factor for malignant progression of mouse oral papillomavirus infections

HPV infections in the oral cavity that progress to cancer are on the increase in the USA. Model systems to study co-factors for progression of these infections are lacking as HPVs are species-restricted and cannot grow in preclinical animal models. We have recently developed a mouse papillomavirus (MmuPV1) oral mucosal infection model that provides opportunities to test, for the first time, the hypothesis that tobacco carcinogens are co-factors that can impact the progression of oral papillomas to squamous cell carcinoma (SCC). Four cohorts of mice per sex were included: (1) infected with MmuPV1 and treated orally with DMSO-saline; (2) infected with MmuPV1 and treated orally with the tobacco carcinogen, dibenzo[def,p]chrysene (DBP); (3) uninfected and treated orally with DMSO-saline, and (4) uninfected and treated orally with DBP. Oral swabs were collected monthly for subsequent assessment of viral load. Oral tissues were collected for in situ viral DNA/RNA detection, viral protein staining, and pathological assessment for hyperplasia, papillomas and SCC at study termination. We observed increased rates of SCC in oral tissue infected with MmuPV1 and treated with DBP when compared to mice treated with DBP or virus individually, each of which showed minimal disease. Virally-infected epithelium showed strong levels of viral DNA/RNA and viral protein E4/L1 staining. In contrast, areas of SCC showed reduced viral DNA staining indicative of lower viral copy per nucleus but strong RNA signals. Several host markers (p120 ctn, p53, S100A9) were also examined in the mouse oral tissues; of particular significance, p120 ctn discriminated normal un-infected epithelium from SCC or papilloma epithelium. In summary, we have confirmed that our infection model is an excellent platform to assess the impact of co-factors including tobacco carcinogens for oral PV cancerous progression. Our findings can assist in the design of novel prevention/treatment strategies for HPV positive vs. HPV negative disease.

Organoid technology in female reproductive biomedicine

Recent developments in organoid technology are revolutionizing our knowledge about the biology, physiology, and function of various organs. Female reproductive biology and medicine also benefit from this technology. Organoids recapitulate features of different reproductive organs including the uterus, fallopian tubes, and ovaries, as well as trophoblasts. The genetic stability of organoids and long-lasting commitment to their tissue of origin during long-term culture makes them attractive substitutes for animal and in vitro models. Despite current limitations, organoids offer a promising platform to address fundamental questions regarding the reproductive system's physiology and pathology. They provide a human source to harness stem cells for regenerative medicine, heal damaged epithelia in specific diseases, and study biological processes in healthy and pathological conditions. The combination of male and female reproductive organoids with other technologies, such as microfluidics technology, would enable scientists to create a multi-organoid-on-a-chip platform for the next step to human-on-a-chip platforms for clinical applications, drug discovery, and toxicology studies. The present review discusses recent advances in producing organoid models of reproductive organs and highlights their applications, as well as technical challenges and future directions.

An Infection-Based Murine Model for Papillomavirus-Associated Head and Neck Cancer

Human papillomavirus (HPV) is the most common sexually transmitted pathogen, and high-risk HPVs contribute to 5% of human cancers, including 25% of head and neck squamous cell carcinomas (HNSCCs). Despite the significant role played by HPVs in HNSCC, there is currently no available in vivo system to model the process from papillomavirus infection to virus-induced HNSCC. In this paper, we describe an infection-based HNSCC model, utilizing a mouse papillomavirus (MmuPV1), which naturally infects laboratory mice. Infections of the tongue epithelium of two immunodeficient strains with MmuPV1 caused high-grade squamous dysplasia with early signs of invasive carcinoma over the course of 4 months. When combined with the oral carcinogen 4-nitroquinoline-1-oxide (4NQO), MmuPV1 caused invasive squamous cell carcinoma (SCC) on the tongue of both immunodeficient and immunocompetent mice. These tumors expressed markers of papillomavirus infection and HPV-associated carcinogenesis. This novel preclinical model provides a valuable new means to study how natural papillomavirus infections contribute to HNSCC.IMPORTANCE The species specificity of papillomavirus has limited the development of an infection-based animal model to study HPV-associated head and neck carcinogenesis. Our study presents a novel in vivo model using the mouse papillomavirus MmuPV1 to study papillomavirus-associated head and neck cancer. In our model, MmuPV1 infects and causes lesions in both immunodeficient and genetically immunocompetent strains of mice. These virally induced lesions carry features associated with both HPV infections and HPV-associated carcinogenesis. Combined with previously identified cancer cofactors, MmuPV1 causes invasive squamous cell carcinomas in mice. This model provides opportunities for basic and translational studies of papillomavirus infection-based head and neck disease.

A Mouse Model of Oropharyngeal Papillomavirus-Induced Neoplasia Using Novel Tools for Infection and Nasal Anesthesia

Human head and neck cancers that develop from the squamous cells of the oropharynx (Oropharyngeal Squamous Cell Carcinomas or OPSCC) are commonly associated with the papillomavirus infection. A papillomavirus infection-based mouse model of oropharyngeal tumorigenesis would be valuable for studying the development and treatment of these tumors. We have developed an efficient system using the mouse papillomavirus (MmuPV1) to generate dysplastic oropharyngeal lesions, including tumors, in the soft palate and the base of the tongue of two immune-deficient strains of mice. To maximize efficiency and safety during infection and endoscopy, we have designed a nose cone for isoflurane-induced anesthesia that takes advantage of a mouse’s need to breathe nasally and has a large window for oral manipulations. To reach and infect the oropharynx efficiently, we have repurposed the Greer Pick allergy testing device as a virus delivery tool. We show that the Pick can be used to infect the epithelium of the soft palate and the base of the tongue of mice directly, without prior scarification. The ability to induce and track oropharyngeal papillomavirus-induced tumors in the mouse, easily and robustly, will facilitate the study of oropharyngeal tumorigenesis and potential treatments.

Mus musculus Papillomavirus 1: a New Frontier in Animal Models of Papillomavirus Pathogenesis

Animal models of viral pathogenesis are essential tools in human disease research. Human papillomaviruses (HPVs) are a significant public health issue due to their widespread sexual transmission and oncogenic potential. Infection-based models of papillomavirus pathogenesis have been complicated by their strict species and tissue specificity. In this Gem, we discuss the discovery of a murine papillomavirus, Mus musculus papillomavirus 1 (MmuPV1), and how its experimental use represents a major advancement in models of papillomavirus-induced pathogenesis/carcinogenesis, and their transmission.

Stress keratin 17 enhances papillomavirus infection-induced disease by downregulating T cell recruitment

High-risk human papillomaviruses (HPVs) cause 5% of human cancers. Despite the availability of HPV vaccines, there remains a strong urgency to find ways to treat persistent HPV infections, as current HPV vaccines are not therapeutic for individuals already infected. We used a mouse papillomavirus infection model to characterize virus-host interactions. We found that mouse papillomavirus (MmuPV1) suppresses host immune responses via overexpression of stress keratins. In mice deficient for stress keratin K17 (K17KO), we observed rapid regression of papillomas dependent on T cells. Cellular genes involved in immune response were differentially expressed in the papillomas arising on the K17KO mice correlating with increased numbers of infiltrating CD8+ T cells and upregulation of IFNγ-related genes, including CXCL9 and CXCL10, prior to complete regression. Blocking the receptor for CXCL9/CXCL10 prevented early regression. Our data provide a novel mechanism by which papillomavirus-infected cells evade host immunity and defines new therapeutic targets for treating persistent papillomavirus infections.

The human papillomavirus 16 E5 gene potentiates MmuPV1-Dependent pathogenesis

The papillomavirus E5 gene contributes to transformation and tumorigenesis; however, its exact function in these processes and viral pathogenesis is unclear. While E5 is present in high-risk mucosotropic HPVs that cause anogenital and head and neck cancers, it is absent in cutaneous HPVs and the recently discovered mouse papillomavirus (MmuPV1), which causes papillomas and squamous cell carcinomas of the skin and mucosal epithelia in laboratory mice. We infected K14E5 transgenic mice, which express the high-risk mucosotropic HPV16 E5 gene in stratified epithelia, with MmuPV1 to investigate the effects of E5 on papillomavirus-induced pathogenesis. Skin lesions in MmuPV1-infected K14E5 mice had earlier onset, higher incidence, and reduced frequency of spontaneous regression compared to those in non-transgenic mice. K14E5 mice were also more susceptible to cervicovaginal cancers when infected with MmuPV1 and treated with estrogen compared to non-transgenic mice. Our studies support the hypothesis that E5 contributes to papillomavirus-induced pathogenesis.

Sexual transmission of murine papillomavirus (MmuPV1) in Mus musculus

Human papillomaviruses (HPVs) are the most common sexually transmitted infectious agents. Because of the species specificity of HPVs, study of their natural transmission in laboratory animals is not possible. The papillomavirus, MmuPV1, which infects laboratory mice (Mus musculus), can cause infections in the female cervicovaginal epithelium of immunocompetent mice that progress to cancer. Here, we provide evidence that MmuPV1 is sexually transmitted in unmanipulated, immunocompetent male and female mice. Female 'donor' mice experimentally infected with MmuPV1 in their lower reproductive tract were housed with unmanipulated male mice. The male mice were then transferred to cages holding 'recipient' female mice. One third of the female recipient mice acquired cervicovaginal infections. Prolonged infections were verified by histopathology and in situ hybridization analyses of both male and recipient female mice at the study endpoint. These findings indicate that MmuPV1 is a new model animal papillomavirus with which to study sexually transmission of papillomaviruses.