Pathology in Permissive Syrian Hamsters after Infection with Species C Human Adenovirus (HAdV-C) Is the Result of Virus Replication: HAdV-C6 Replicates More and Causes More Pathology than HAdV-C5.

Syrian hamsters are permissive for the replication of species C human adenoviruses (HAdV-C). The virus replicates to high titers in the liver of these animals after intravenous infection, while respiratory infection results in virus replication in the lung. Here we show that two types belonging to species C, HAdV-C5 and HAdV-C6, replicate to significantly different extents and cause pathology with significantly different severities, with HAdV-C6 replicating better and inducing more severe and more widespread lesions. The virus burdens in the livers of HAdV-C6-infected hamsters are higher than the virus burdens in HAdV-C5-infected ones because more of the permissive hepatocytes get infected. Furthermore, when hamsters are infected intravenously with HAdV-C6, live, infectious virus can be isolated from the lung and the kidney, which is not seen with HAdV-C5. Similarly to mouse models, in hamsters, HAdV-C6 is sequestered by macrophages to a lesser degree than HAdV-C5. Depletion of Kupffer cells from the liver greatly increases the replication of HAdV-C5 in the liver, while it has only a modest effect on the replication of HAdV-C6. Elimination of Kupffer cells also dramatically increases the pathology induced by HAdV-C5. These findings indicate that in hamsters, pathology resulting from intravenous infection with adenoviruses is caused mostly by replication in hepatocytes and not by the abortive infection of Kupffer cells and the following cytokine storm.IMPORTANCE Immunocompromised human patients can develop severe, often lethal adenovirus infections. Respiratory adenovirus infection among military recruits is a serious problem, in some cases requiring hospitalization of the patient. Furthermore, adenovirus-based vectors are frequently used as experimental viral therapeutic agents. Thus, it is imperative that we investigate the pathogenesis of adenoviruses in a permissive animal model. Syrian hamsters are susceptible to infection with certain human adenoviruses, and the pathology accompanying these infections is similar to what is observed with adenovirus-infected human patients. We demonstrate that replication in permissive cells in a susceptible host animal is a major part of the mechanism by which systemic adenovirus infection induces pathology, as opposed to the chiefly immune-mediated pathology observed in nonsusceptible hosts. These findings support the use of compounds inhibiting adenovirus replication as a means to block adenovirus-induced pathology.

Correction: STAT2 Knockout Syrian Hamsters Support Enhanced Replication and Pathogenicity of Human Adenovirus, Revealing an Important Role of Type I Interferon Response in Viral Control.

[This corrects the article DOI: 10.1371/journal.ppat.1005084.].

STAT2 Knockout Syrian Hamsters Support Enhanced Replication and Pathogenicity of Human Adenovirus, Revealing an Important Role of Type I Interferon Response in Viral Control.

Human adenoviruses have been studied extensively in cell culture and have been a model for studies in molecular, cellular, and medical biology. However, much less is known about adenovirus replication and pathogenesis in vivo in a permissive host because of the lack of an adequate animal model. Presently, the most frequently used permissive immunocompetent animal model for human adenovirus infection is the Syrian hamster. Species C human adenoviruses replicate in these animals and cause pathology that is similar to that seen with humans. Here, we report findings with a new Syrian hamster strain in which the STAT2 gene was functionally knocked out by site-specific gene targeting. Adenovirus-infected STAT2 knockout hamsters demonstrated an accentuated pathology compared to the wild-type control animals, and the virus load in the organs of STAT2 knockout animals was 100- to 1000-fold higher than that in wild-type hamsters. Notably, the adaptive immune response to adenovirus is not adversely affected in STAT2 knockout hamsters, and surviving hamsters cleared the infection by 7 to 10 days post challenge. We show that the Type I interferon pathway is disrupted in these hamsters, revealing the critical role of interferon-stimulated genes in controlling adenovirus infection. This is the first study to report findings with a genetically modified Syrian hamster infected with a virus. Further, this is the first study to show that the Type I interferon pathway plays a role in inhibiting human adenovirus replication in a permissive animal model. Besides providing an insight into adenovirus infection in humans, our results are also interesting from the perspective of the animal model: STAT2 knockout Syrian hamster may also be an important animal model for studying other viral infections, including Ebola-, hanta-, and dengue viruses, where Type I interferon-mediated innate immunity prevents wild type hamsters from being effectively infected to be used as animal models.

Deficiency of antigen-specific B cells results in decreased Trypanosoma cruzi systemic but not mucosal immunity due to CD8 T cell exhaustion.

Vaccines against mucosally invasive, intracellular pathogens must induce a myriad of immune responses to provide optimal mucosal and systemic protection, including CD4(+) T cells, CD8(+) T cells, and Ab-producing B cells. In general, CD4(+) T cells are known to provide important helper functions for both CD8(+) T cell and B cell responses. However, the relative importance of CD4(+) T cells, CD8(+) T cells, and B cells for mucosal protection is less clearly defined. We have studied these questions in detail using the murine model of Trypanosoma cruzi infection. Despite our initial hypothesis that mucosal Abs would be important, we show that B cells are critical for systemic, but not mucosal, T. cruzi protective immunity. B cell-deficient mice developed normal levels of CD8(+) effector T cell responses early after mucosal T. cruzi infection and T. cruzi trans-sialidase vaccination. However, after highly virulent systemic challenge, T. cruzi immune mice lacking T. cruzi-specific B cells failed to control parasitemia or prevent death. Mechanistically, T. cruzi-specific CD8(+) T cells generated in the absence of B cells expressed increased PD-1 and Lag-3 and became functionally exhausted after high-level T. cruzi systemic challenge. T. cruzi immune serum prevented CD8(+) T cell functional exhaustion and reduced mortality in mice lacking B cells. Overall, these results demonstrate that T. cruzi-specific B cells are necessary during systemic, but not mucosal, parasite challenge.

Increased bioavailability of celecoxib under fed versus fasted conditions is determined by postprandial bile secretion as demonstrated in a dynamic gastrointestinal model.

The objective of this study was to utilize physiologically relevant dynamic dissolution testing with the TNO intestinal model (TIM-1) in vitro gastrointestinal model to investigate the bioaccessibility of celecoxib. A single 200-mg dose of celecoxib was evaluated under average adult human physiological conditions simulated in the TIM-1 system. The in vitro data were compared with the clinically established pharmacokinetic data. When expressed as a percent of drug that progresses from the duodenum to the jejunum and ileum compartments (bioaccessible sites), the study demonstrated a 2-fold increase in the total bioaccessibility for celecoxib when co-administered with a high-fat meal as opposed to co-administration with a glass of water (fasted conditions). That increase in bioaccessibility was similar to a 1.2 to 1.6-fold increase in systemic exposure in adults and children following co-administration with a high-fat meal when compared to the exposure measured when celecoxib was co-administered with only water. Following that comparison, the flexibility of the TIM-1 system was used to more specifically investigate individual parameters of gastrointestinal conditions, such as the rate of bile secretion (emptying of the bile bladder) that accompanies high-fat meal consumption. We demonstrated that increased bile secretion after co-administration of a high-fat meal played a more important role in the increased celecoxib bioaccessibility than did the food matrix. This indicates that in humans without a bile bladder the exposure of celecoxib administered with food might be as low as under fasted state.

Lethal NK-mediated inflammation induced by IL-12 in the absence of polymorphic and nonpolymorphic MHC class I molecules.

Interleukin-12 is a potent activator and initiator of type-1 T cell development, and can be used as an adjuvant to bias for the development of vaccine-induced Th1 immune responses. During vaccination of MHC class I deficient beta-2 microglobulin knockout mice (ß2M(-/-)) with an IL-12/αIL-4 Th1 biasing procedure, all of the mice died. None of the IL-12/αIL-4 treated wild type mice developed any noticeable complications. We hypothesized that NK cells may be activated by IL-12 treatment in these ß2M(-/-) mice, leading to necrosis and eventual death. IL-12/αIL-4 treatment of ß2M(-/-) mice resulted in increased NK cell numbers and activation status (IFN-γ(+), CD69(+)). Finally, in vivo depletion of NK cells reversed the pathology induced by IL-12/αIL-4 treatment in ß2M deficient mice. These results indicate that IL-12 combined with αIL-4 irreversibly activates NK cells leading to a disseminated inflammatory pathology and death in ß2M(-/-) mice.

Characterization and Prevention of Hypovitaminosis C in Chimeric Mice with Humanized Livers.

Humanized liver chimeric mice (PXB-mice) are generated by the transplantation of human hepatocytes into mice that have severe combined immunodeficiency and express an albumin-promoted urokinase-type plasminogen activator (cDNA-uPA/SCID) transgene. Human hepatocytes cannot synthesize ascorbic acid (AA; commonly called vitamin C) and humans require supplementation to prevent vitamin C deficiency. PXB-mouse livers contain up to approximately 95% human hepatocytes, which likely affects AA synthesis. To determine whether dietary AA supplementation prevents scurvy-like symptoms and death in PXB-mice, a 12 week study that compared nonsupplemented and supplemented PXB-mice was conducted. Approximately 4 weeks into the study, PXB-mice without dietary supplementation of AA displayed weight loss and clinical signs of hypovitaminosis C, including hunched posture, unkempt appearance, and lameness. Pathologic evaluation of nonsupplemented PXB-mice revealed lesions consistent with hypovitaminosis C. Mean serum AA concentrations in the nonsupplemented PXB-mice were below the limit of quantitation (0.5 µg/mL) and were substantially less than those of controls. AA was also measured in a number of tissues, including adrenal gland, brain, liver, and testis; low AA concentrations were similarly observed in tissues obtained from the nonsupplemented PXB-mice. Collectively, these findings support AA supplementation in PXB-mice to prevent the development of hypovitaminosis C and the potential utility of nonsupplemented PXB-mice as an animal model of scurvy.

A mouse model of lethal infection for evaluating prophylactics and therapeutics against Monkeypox virus.

Monkeypox virus (MPXV) is an orthopoxvirus closely related to variola, the etiological agent of smallpox. In humans, MPXV causes a disease similar to smallpox and is considered to be an emerging infectious disease. Moreover, the use of MPXV for bioterroristic/biowarfare activities is of significant concern. Available small animal models of human monkeypox have been restricted to mammals with poorly defined biologies that also have limited reagent availability. We have established a murine MPXV model utilizing the STAT1-deficient C57BL/6 mouse. Here we report that a relatively low-dose intranasal (IN) infection induces 100% mortality in the stat1(-)(/)(-) model by day 10 postinfection with high infectious titers in the livers, spleens, and lungs of moribund animals. Vaccination with modified vaccinia virus Ankara (MVA) followed by a booster vaccination is sufficient to protect against an intranasal MPXV challenge and induces an immune response more robust than that of a single vaccination. Furthermore, antiviral treatment with CMX001 (HDP-cidofovir) and ST-246 protects when administered as a regimen initiated on the day of infection. Thus, the stat1(-)(/)(-) model provides a lethal murine platform for evaluating therapeutics and for investigating the immunological and pathological responses to MPXV infection.

Hexadecyloxypropyl-cidofovir, CMX001, prevents adenovirus-induced mortality in a permissive, immunosuppressed animal model.

Adenoviruses (Ads) cause a wide array of end-organ and disseminated diseases in severely immunosuppressed patients. For example, approximately 20% of pediatric allogeneic hematopoietic stem cell transplant recipients develop disseminated Ad infection, and the disease proves fatal in as many as 50-80% of these patients. Ad infections are a serious problem for solid-organ transplant recipients and AIDS patients as well. Unfortunately, there are no antiviral drugs approved specifically to treat these infections. A suitable animal model that is permissive for Ad replication would help in the discovery process. Here we identify an animal model to study Ad pathogenesis and the efficacy of antiviral compounds. We show that human serotype 5 Ad (Ad5) causes severe systemic disease in immunosuppressed Syrian hamsters that is similar to that seen in immunocompromised patients. We also demonstrate that hexadecyloxypropyl-cidofovir (CMX001) rescues the hamsters from a lethal challenge with Ad5. The antiviral drug provided protection both prophylactically and when given up to 2 days after i.v. exposure to Ad5. CMX001 acts by reducing Ad replication in key target organs. Thus, the immunosuppressed Syrian hamster is a powerful model to evaluate anti-Ad drugs, and its use can facilitate the entry of drugs such as CMX001 into clinical trials.

CRISPR-Cas9 gene editing of hepatitis B virus in chronically infected humanized mice.

Chronic hepatitis B virus (HBV) infection is a major public health problem. New treatment approaches are needed because current treatments do not target covalently closed circular DNA (cccDNA), the template for HBV replication, and rarely clear the virus. We harnessed adeno-associated virus (AAV) vectors and CRISPR-Staphylococcus aureus (Sa)Cas9 to edit the HBV genome in liver-humanized FRG mice chronically infected with HBV and receiving entecavir. Gene editing was detected in livers of five of eight HBV-specific AAV-SaCas9-treated mice, but not control mice, and mice with detectable HBV gene editing showed higher levels of SaCas9 delivery to HBV+ human hepatocytes than those without gene editing. HBV-specific AAV-SaCas9 therapy significantly improved survival of human hepatocytes, showed a trend toward decreasing total liver HBV DNA and cccDNA, and was well tolerated. This work provides evidence for the feasibility and safety of in vivo gene editing for chronic HBV infections, and it suggests that with further optimization, this approach may offer a plausible way to treat or even cure chronic HBV infections.

Acute lymphoid and gastrointestinal toxicity induced by selective p38alpha map kinase and map kinase-activated protein kinase-2 (MK2) inhibitors in the dog.

Exposure to moderately selective p38alpha mitogen-activated protein kinase (MAPK) inhibitors in the Beagle dog results in an acute toxicity consisting of mild clinical signs (decreased activity, diarrhea, and fever), lymphoid necrosis and depletion in the gut-associated lymphoid tissue (GALT), mesenteric lymph nodes and spleen, and linear colonic and cecal mucosal hemorrhages. Lymphocyte apoptosis and necrosis in the GALT is the earliest and most prominent histopathologic change observed, followed temporally by neutrophilic infiltration and acute inflammation of the lymph nodes and spleen and multifocal mucosal epithelial necrosis and linear hemorrhages in the colon and cecum. These effects are not observed in the mouse, rat, or cynomolgus monkey. To further characterize the acute toxicity in the dog, a series of in vivo, in vitro, and immunohistochemical studies were conducted to determine the relationship between the lymphoid and gastrointestinal (GI) toxicity and p38 MAPK inhibition. Results of these studies demonstrate a direct correlation between p38alpha MAPK inhibition and the acute lymphoid and gastrointestinal toxicity in the dog. Similar effects were observed following exposure to inhibitors of MAPK-activated protein kinase-2 (MK2), further implicating the role of p38alpha MAPK signaling pathway inhibition in these effects. Based on these findings, the authors conclude that p38alpha MAPK inhibition results in acute lymphoid and GI toxicity in the dog and is unique among the species evaluated in these studies.

The application of discovery toxicology and pathology towards the design of safer pharmaceutical lead candidates.

Toxicity is a leading cause of attrition at all stages of the drug development process. The majority of safety-related attrition occurs preclinically, suggesting that approaches to identify 'predictable' preclinical safety liabilities earlier in the drug development process could lead to the design and/or selection of better drug candidates that have increased probabilities of becoming marketed drugs. In this Review, we discuss how the early application of preclinical safety assessment--both new molecular technologies as well as more established approaches such as standard repeat-dose rodent toxicology studies--can identify predictable safety issues earlier in the testing paradigm. The earlier identification of dose-limiting toxicities will provide chemists and toxicologists the opportunity to characterize the dose-limiting toxicities, determine structure-toxicity relationships and minimize or circumvent adverse safety liabilities.

Immunosuppression enhances oncolytic adenovirus replication and antitumor efficacy in the Syrian hamster model.

We recently described an immunocompetent Syrian hamster model for oncolytic adenoviruses (Ads) that permits virus replication in tumor cells as well as some normal tissues. This model allows exploration of interactions between the virus, tumor, normal organs, and host immune system that could not be examined in the immunodeficient or nonpermissive animal models previously used in the oncolytic Ad field. Here we asked whether the immune response to oncolytic Ad enhances or limits antitumor efficacy. We first determined that cyclophosphamide (CP) is a potent immunosuppressive agent in the Syrian hamster and that CP alone had no effect on tumor growth. Importantly, we found that the antitumor efficacy of oncolytic Ads was significantly enhanced in immunosuppressed animals. In animals that received virus therapy plus immunosuppression, significant differences were observed in tumor histology, and in many cases little viable tumor remained. Notably, we also determined that immunosuppression allowed intratumoral virus levels to remain elevated for prolonged periods. Although favorable tumor responses can be achieved in immunocompetent animals, the rate of virus clearance from the tumor may lead to varied antitumor efficacy. Immunosuppression, therefore, allows sustained Ad replication and oncolysis, which leads to substantially improved suppression of tumor growth.

Efficacy of hepatitis B virus ribonuclease H inhibitors, a new class of replication antagonists, in FRG human liver chimeric mice.

Chronic hepatitis B virus infection cannot be cured by current therapies, so new treatments are urgently needed. We recently identified novel inhibitors of the hepatitis B virus ribonuclease H that suppress viral replication in cell culture. Here, we employed immunodeficient FRG KO mice whose livers had been engrafted with primary human hepatocytes to ask whether ribonuclease H inhibitors can suppress hepatitis B virus replication in vivo. Humanized FRG KO mice infected with hepatitis B virus were treated for two weeks with the ribonuclease H inhibitors #110, an α-hydroxytropolone, and #208, an N-hydroxypyridinedione. Hepatitis B virus viral titers and S and e antigen plasma levels were measured. Treatment with #110 and #208 caused significant reductions in plasma viremia without affecting hepatitis B virus S or e antigen levels, and viral titers rebounded following treatment cessation. This is the expected pattern for inhibitors of viral DNA synthesis. Compound #208 suppressed viral titers of both hepatitis B virus genotype A and C isolates. These data indicate that Hepatitis B virus replication can be suppressed during infection in an animal by inhibiting the viral ribonuclease H, validating the ribonuclease H as a novel target for antiviral drug development.

Uncovering a Predictive Molecular Signature for the Onset of NASH-Related Fibrosis in a Translational NASH Mouse Model.

BACKGROUND & AIMS: The incidence of nonalcoholic steatohepatitis (NASH) is increasing. The pathophysiological mechanisms of NASH and the sequence of events leading to hepatic fibrosis are incompletely understood. The aim of this study was to gain insight into the dynamics of key molecular processes involved in NASH and to rank early markers for hepatic fibrosis. METHODS: A time-course study in low-density lipoprotein-receptor knockout. Leiden mice on a high-fat diet was performed to identify the temporal dynamics of key processes contributing to NASH and fibrosis. An integrative systems biology approach was used to elucidate candidate markers linked to the active fibrosis process by combining transcriptomics, dynamic proteomics, and histopathology. The translational value of these findings were confirmed using human NASH data sets. RESULTS: High-fat-diet feeding resulted in obesity, hyperlipidemia, insulin resistance, and NASH with fibrosis in a time-dependent manner. Temporal dynamics of key molecular processes involved in the development of NASH were identified, including lipid metabolism, inflammation, oxidative stress, and fibrosis. A data-integrative approach enabled identification of the active fibrotic process preceding histopathologic detection using a novel molecular fibrosis signature. Human studies were used to identify overlap of genes and processes and to perform a network biology-based prioritization to rank top candidate markers representing the early manifestation of fibrosis. CONCLUSIONS: An early predictive molecular signature was identified that marked the active profibrotic process before histopathologic fibrosis becomes manifest. Early detection of the onset of NASH and fibrosis enables identification of novel blood-based biomarkers to stratify patients at risk, development of new therapeutics, and help shorten (pre)clinical experimental time frames.

Comparative 13-week inhalation study of cigarette smoke from cigarettes containing cast sheet tobacco.

A subchronic, nose-only inhalation study was conducted to compare the effects of mainstream smoke from a reference cigarette containing conventional reconstituted tobacco sheet at 30% of the finished blend to mainstream smoke from cigarettes containing 10% or 15% cast sheet (a specific type of reconstituted tobacco sheet) substituted for part of the conventional reconstituted tobacco. Male and female Sprague-Dawley rats were exposed for 1 h/day, 5 d/wk, for 13 wk to mainstream smoke at 0, 0.06, 0.20, or 0.80 mg wet total particulate matter per liter of air. Clinical signs, body and organ weights, clinical chemistry, hematology, carboxyhemoglobin (COHb), serum nicotine, plethysmography, gross pathology, and histopathology were determined. Exposure to cigarette smoke induced a number of changes in respiratory physiology, histopathology, and serum nicotine and COHb levels when compared to sham animals. When corresponding dose groups of reference and cast sheet mainstream smokes were compared, no biological differences were noted. At the end of the exposure period, subsets of rats from each group were maintained without smoke exposures for an additional 13 wk (recovery period). At the end of the recovery period, there were no statistically significant differences in histopathological findings observed between the reference and either cast sheet cigarette. Substitution of 10% or 15% cast sheet tobacco for conventional reconstituted tobacco sheet does not alter the inhalation toxicology of the mainstream smoke when compared to mainstream smoke from a reference cigarette containing conventional reconstituted tobacco sheet.

Valganciclovir inhibits human adenovirus replication and pathology in permissive immunosuppressed female and male Syrian hamsters.

Adenovirus infections of immunocompromised pediatric hematopoietic stem cell transplant patients can develop into serious and often deadly multi-organ disease. There are no drugs approved for adenovirus infections. Cidofovir (an analog of 2-deoxycytidine monophosphate) is used at times but it can be nephrotoxic and its efficacy has not been proven in clinical trials. Brincidofovir, a promising lipid-linked derivative of cidofovir, is in clinical trials. Ganciclovir, an analog of 2-deoxyguanosine, has been employed occasionally but with unknown efficacy in the clinic. In this study, we evaluated valganciclovir against disseminated adenovirus type 5 (Ad5) infection in our permissive immunosuppressed Syrian hamster model. We administered valganciclovir prophylactically, beginning 12 h pre-infection or therapeutically starting at Day 1, 2, 3, or 4 post-infection. Valganciclovir significantly increased survival, reduced viral replication in the liver, and mitigated the pathology associated with Ad5 infection. In cultured cells, valganciclovir inhibited Ad5 DNA replication and blocked the transition from early to late stage of infection. Valganciclovir directly inhibited Ad5 DNA polymerase in vitro, which may explain, at least in part, its mechanism of action. Ganciclovir and valganciclovir are approved to treat infections by certain herpesviruses. Our results support the use of valganciclovir to treat disseminated adenovirus infections in immunosuppressed patients.

Epididymal cribriform hyperplasia with nuclear atypia in p53 homozygous knockout mice on a mixed 129/Sv-FVB/N background.

Epididymal cribriform hyperplasia (ECH) is a variant of normal epididymal histologic features in men, and has also been reported in rats, mice, dogs, cats, and bulls. The epididymal change has been associated with aging, testicular atrophy, cryptorchidism, and germ cell tumors. Epididymal cribriform hyperplasia was observed in p53 homozygous knockout mice on a mixed 129/Sv-FVB/N background, but not in wild-type or heterozygous mice. The aim of the study reported here was to determine the prevalence and characterize the morphologic, immunohistochemical, and ultrastructural features of ECH in these mice. Epididymal cribriform hyperplasia was present in 88% (72/82) of male mice ranging in age from seven to 65 weeks. The lesion was characterized microscopically by epithelial cells with atypical hyperchromatic nuclei, vacuolization, intratubular lumina formation, infrequent apoptosis, and rare mitotic figures. In contrast to germ cells, the cells of ECH did not express alpha-fetoprotein, carcinoembryonic antigen, or S-100. Ultrastructurally, the cells were pleomorphic with stereocilia at their apical borders and within intratubular lumina, and were supported by a basement membrane. Although 14% (10/72) of mice had concomitant testicular neoplasia, ECH did not appear to be a preneoplastic change. Investigators using these mice for modeling human disease should be aware of the background prevalence of this lesion.

Autoimmune gastritis mediated by CD4+ T cells promotes the development of gastric cancer.

Chronic inflammation is a major risk factor for cancer, including gastric cancers and other gastrointestinal cancers. For example, chronic inflammation caused by autoimmune gastritis (AIG) is associated with an increased risk of gastric polyps, gastric carcinoid tumors, and possibly adenocarcinomas. In this study, we characterized the progression of gastric cancer in a novel mouse model of AIG. In this model, disease was caused by CD4(+) T cells expressing a transgenic T-cell receptor specific for a peptide from the H(+)/K(+) ATPase proton pump, a protein expressed by parietal cells in the stomach. AIG caused epithelial cell aberrations that mimicked most of those seen in progression of human gastric cancers, including chronic gastritis followed by oxyntic atrophy, mucous neck cell hyperplasia, spasmolytic polypeptide-expressing metaplasia, dysplasia, and ultimately gastric intraepithelial neoplasias. Our work provides the first direct evidence that AIG supports the development of gastric neoplasia and provides a useful model to study how inflammation drives gastric cancer.

Evaluation of disease and viral biomarkers as triggers for therapeutic intervention in respiratory mousepox - an animal model of smallpox.

The human population is currently faced with the potential use of natural or recombinant variola and monkeypox viruses as biological weapons. Furthermore, the emergence of human monkeypox in Africa and its expanding environs poses a significant natural threat. Such occurrences would require therapeutic and prophylactic intervention with antivirals to minimize morbidity and mortality of exposed populations. Two orally-bioavailable antivirals are currently in clinical trials; namely CMX001, an ether-lipid analog of cidofovir with activity at the DNA replication stage and ST-246, a novel viral egress inhibitor. Both of these drugs have previously been evaluated in the ectromelia/mousepox system; however, the trigger for intervention was not linked to a disease biomarker or a specific marker of virus replication. In this study we used lethal, intranasal, ectromelia virus infections of C57BL/6 and hairless SKH1 mice to model human disease and evaluate exanthematous rash (rash) as an indicator to initiate antiviral treatment. We show that significant protection can be provided to C57BL/6 mice by CMX001 or ST-246 when therapy is initiated on day 6 post infection or earlier. We also show that significant protection can be provided to SKH1 mice treated with CMX001 at day 3 post infection or earlier, but this is four or more days before detection of rash (ST-246 not tested). Although in this model rash could not be used as a treatment trigger, viral DNA was detected in blood by day 4 post infection and in the oropharyngeal secretions (saliva) by day 2-3 post infection - thus providing robust and specific markers of virus replication for therapy initiation. These findings are discussed in the context of current respiratory challenge animal models in use for the evaluation of poxvirus antivirals.