Syrian Hamster as a Permissive Model for Testing Anti-Adenovirus Drugs

描述（由申请人提供）：人类腺病毒（Ads）是免疫抑制人类的一个重要问题，特别是在接受同种异体干细胞移植的儿童中。这些儿童患者中约有20%发生弥散性Ad感染，约有一半的患者死亡。目前还没有抗病毒药物被批准用于治疗这些Ad感染。西多福韦和利巴韦林在某些情况下使用，但不知道它们是否有效，因为它们没有以系统控制的方式进行研究。抗广告药物的开发一直受到阻碍，因为没有动物模型来复制人类广告。这是因为广告具有高度的物种特异性。我们正在开发叙利亚仓鼠作为肿瘤模型，以研究溶瘤性Ad载体的功效、复制、毒性和生物分布。我们发现，在瘤内或静脉注射后，人类Ad血清5型（Ad5）和基于Ad5的溶瘤载体在仓鼠肿瘤、肝脏、肺和其他器官中复制良好。令人非常感兴趣的是，使用环磷酰胺（CP）对仓鼠进行免疫抑制会导致病毒的高水平复制。在给药后，肿瘤和肝脏中的高水平复制持续至少42天（实验结束）。基于这些观察结果，我们建议使用cp免疫抑制的叙利亚仓鼠作为新的动物模型来评估抗Ad药物对免疫功能低下患者播散性Ad感染的疗效和毒理学。为了获得该模型的初步原理证明，我们将评估十六烷基氧基丙基西多福韦（HDP-CDV）的抗ad功效和毒理学。在特异性目标1中，我们将检测HDP- CDV对CP免疫抑制仓鼠肝脏中Ad5（人类Ad物种C的一员）复制的抑制作用。Ad5在肝脏和血液中的复制将通过qPCR、组织培养感染剂量测定50 （TCID50测定）和Ad病毒粒子蛋白的免疫组织化学来确定。毒性将根据肝脏组织病理学和血清化学进行评估。在Aim 2中，我们将确定人类Ad的A、B、D、E和F种血清型是否在CP免疫抑制的仓鼠肝脏中复制。如果它们确实复制，那么我们将确定HDP-CDV是否抑制它们在培养细胞中的复制。

DESCRIPTION (provided by applicant): Human adenoviruses (Ads) are a significant problem in immunosuppressed humans, especially in children undergoing allogeneic stem cell transplants. About 20% of these pediatric patients develop disseminated Ad infections and about half of the patients die. There are no anti-viral drugs approved to treat these Ad infections. Cidofovir and ribavirin are used in some cases, but it is not known whether they are effective because they have not been studied in a systematic controlled manner. Development of anti-Ad drugs has been hindered because there is no animal model for replicating human Ads. This is because Ads are highly species-specific. We are developing the Syrian hamster as a tumor model to study the efficacy, replication, toxicity, and biodistribution of oncolytic Ad vectors. We showed that human Ad serotype 5 (Ad5) and Ad5-based oncolytic vectors replicate well in hamster tumors, livers, lungs, and other organs following intratumoral or intravenous injection. Of great interest, immunosuppression of the hamsters using cyclophosphamide (CP) leads to much higher levels of replication of the viruses. Replication continues at high levels in tumors and livers for at least 42 days (the end of the experiment) following administration of the virus. Based on these observations, we propose to use CP-immunosuppressed Syrian hamsters as a new animal model to evaluate the efficacy and toxicology of anti-Ad drugs on disseminated Ad infections in immunocompromised patients. To obtain initial proof-of-principle for this model, we will evaluate the anti-Ad efficacy and toxicology of hexadecyloxypropyl-cidofovir (HDP-CDV). In Specific Aim 1 we will examine HDP- CDV inhibition of Ad5 (a member of human Ad Species C) replication in the liver of hamsters immunosuppressed by CP. Ad5 replication in the liver and blood will be determined by qPCR, a tissue culture infectious dose assay 50 (TCID50 assay), and immunohistochemistry for an Ad virion protein. Toxicity will be assessed based on histopathology of the liver and serum chemistry. In Aim 2 we will determine whether serotypes in human Ad Species A, B, D, E, and F replicate in the liver of hamsters immunosuppressed by CP. If they do replicate, then we will determine whether HDP-CDV inhibits their replication in cultured cells. When humans become severely immunosuppressed, for example when children with leukemia have their immune system destroyed by immunosuppressed drugs prior to receiving bone marrow stem cell transplants, these patients often develop systemic infections with different viruses. These infections, which may be due to new infections or to activation of latent viruses, occur because the patient's immune system cannot keep the virus in check. Adenoviruses are one of the types of viruses that cause these infections, and the infections frequently result in the death of the patient. Unfortunately, no anti-adenovirus drugs have been examined in controlled clinical trials, and therefore no drugs are approved to treat these adenovirus infections. One reason that clinical trials for anti-adenovirus drugs have not been conducted is because there is no suitable animal model available to test the effectiveness and toxicity of such drugs. In this grant application, we propose to develop the Syrian hamster as an immunosuppressed animal model to evaluate anti-adenovirus drugs. Success in this project could lead to the eventual approval of drugs to treat adenovirus infections in immunosuppressed patients.