Development of Ebola VP30 Transgenic Hamsters to Complement a Biologically Contained Ebolavirus

Currently, there are no licensed countermeasures (vaccines or antiviral drugs) to protect U.S. Service members from infections caused by ebolaviruses. Given the tremendous public health risk associated with Zaire ebolavirus (EBOV) infections, and the potential use of this virus as a bioweapon, there is a great interest in and need for effective and safe antiviral drugs to combat this pathogen. Therefore, this application is in response to the Fiscal Year 2019 Peer Reviewed Medical Research Program Topic Area "Emerging Infectious Diseases." Specifically, this application addresses the Area of Encouragement that focuses on the "research, development, and validation of animal models for the study of infectious diseases that clearly show the pathophysiological mechanism of the disease and provide translational data to advance drug products to human clinical trial." For EBOV therapeutic research, golden Syrian hamsters are an ideal small animal model. Infection of golden Syrian hamsters with EBOV (a mouse-adapted strain) results in a disease profile similar to that observed in nonhuman primates. The disease profile in infected hamsters includes coagulopathy, lymphocyte apoptosis, cytokine dysregulation, necrosis in target organs, and fatality. In contrast, mice and guinea pigs infected with rodent-specific strains of EBOV show few, if any, disease characteristics. In this proposal, we will use a biologically contained (BC)-EBOV that lacks the essential viral protein VP30, which renders the virus biologically inert and safe to use outside of highly specialized biosafety level (BSL)-4 containment. The introduction of the EBOV VP30 gene into golden Syrian hamsters should lead to VP30 transgene expression in the majority of tissues and cell types of the transgenic animals. We hypothesize that the expression of the EBOV VP30 transgene will allow the systemic replication of the BC-EBOV. Efficient virus replication in organs such as the liver, spleen, and lymphatic tissue will create a lethal disease phenotype with pathologies similar to those observed in EBOV-infected nonhuman primates and humans. This new small animal model can then be used to examine EBOV pathogenesis and accelerate the development and evaluation of countermeasures efficiently and safely under BSL-2/-3 containment. In Aim 1, we will generate EBOV VP30 transgenic golden Syrian hamsters that will complement virus replication in vivo of a BC-EBOV that lacks the critical viral gene VP30. We plan to drive the expression of the VP30 transgene in transgenic hamsters by using the human polyubiquitin-C promoter, which has previously been successfully used to drive a different reporter gene in transgenic hamsters. Once an inbred line of EBOV VP30 transgenic hamsters is established, in Aim 2, we will infect transgenic animals with BC-EBOV to determine lethality in this animal model. Then, we will assess virus replication in different organs. In addition, we will conduct hematology and coagulation assays along with histopathology studies to determine whether the disease profile of BC-EBOV-infected EBOV VP30 transgenic hamsters is similar to that observed in wild-type hamsters infected with wild-type EBOV. Collectively, these studies will generate a new small animal model for EBOV infection with pathophysiological phenotypes analogous to those observed in experimentally infected nonhuman primates and in human cases during outbreaks. This animal model can be utilized safely outside of BSL-4 containment to evaluate anti-Ebola drugs. We anticipate that this novel animal model will, therefore, be an important first step in the evaluation of antiviral drugs against Ebola viruses. Some of these antiviral drugs may ultimately be approved for human use to benefit both U.S. Service members and the general public. Less