PPG: SARS-CoV-host cell interactions and vaccine development

OVERVIEW-SUMMARYThe emergence of the Severe Acute Respiratory Syndrome (SARS) in 2002-3 and the Middle EastRespiratory Syndrome (MERS) in 2012 demonstrates that zoonotic coronaviruses (CoV) have and willlikely continue to spread from zoonotic sources to infect Human populations. MERS-CoV continues tocirculate in camels and to spread to susceptible humans, highlighting the need to better understandthe pathogenesis of diseases mediated by pathogenic human respiratory CoV. In this PPG,investigators with experience in coronavirus pathogenesis, molecular biology, immunology andvaccinology will work together to understand how virus factors and dysregulated innate and adaptiveimmune responses contribute to MERS and SARS disease in young and aged animals and in animalswith co-morbidities. All of the projects will utilize newly developed mice expressing human MERSreceptor (DPP4) in lieu of the mouse receptor (hDPP4-KI) and a mouse-virulent MERS-CoV, selectedin these mice (MERSMA). Project 1 will use MERSMA to investigate the role of aging in infected mice.Project 1 is also based on published data showing that specific eiconsanoids with anti-inflammatoryproperites and their upstream phopholipases increase during aging, contributing to a delayed immuneresponse after SARS-CoV (and by extension, perhaps MERSMA) infection. Project 2 is based onpreliminary data showing that MERS-CoV has a greater dependence on host cell proteases for virusentry than does SARS-CoV. This project will investigate unique mutations found in the surface (S)glycoprotein of MERSMA that appear to affect protease function. Project 3 will investigate howMERSMA causes more severe disease than the initial human EMC/2012 strain, with focus on theORF4b accessory protein. This project will also investigate how hDPP4 contributes to diseaseseverity. Project 4 is based on published data showing that the CoV E protein has ion channel activity,is a virulence factor and contains a PDZ binding domain (PBM), which is critical for virus viability. Thisproject will focus on how the E protein causes edema in lungs and on the role of the PBM inpathogenesis. A novel PBM in the C terminal of E arose in MERSMA during mouse passage and itsrole will be studied. This project will also continue to develop safe, live attenuated MERS and SARSvaccines. All of the projects will use the Animal/Virology Core, which will provide nonrecombinant andrecombinant MERS-CoV and SARS-CoVs and will monitor and analyze infected mice. Using the Corefor these purposes will maximize experimental quality control and effective use of our resources.These projects are all interrelated and collaborative, will take advantage of the unique skills andexpertise of the project directors and provide new information about MERS and SARS pathogenesisthat is essential to vaccine development.