Live imaging of SARS-CoV-2 infection in novel humanized mice

PROJECT SUMMARY The SARS-CoV-2 pandemic is an unprecedented challenge for the global health community, and there is urgent need to understand the pathogenesis of SARS-CoV-2 and emerging viral variants. The pathology associated with SARS-CoV-2 infection ranges from asymptomatic to severe, in some cases fatal disease that correlates with inflammatory cell death during infection, activation of the immune system and release of inflammatory cytokines or a "cytokine storm". Unfortunately, available animal models of SARS-CoV-2 infection do not fully recapitulate the human immune response to viral infection due to multiple differences in genomes, molecular and metabolic pathways, and immune system regulation. The goal of our supplemental proposal in response to PA-20-272 is use a panel of translational humanized mouse models developed by Dr. Leonard Shultz at The Jackson Laboratory to study the clearance of SARS-CoV-2 and the variants that are continually emerging, and for the testing of human-specific therapies that will mitigate the pathology associated with COVID-19. In addition, we will use a novel in vivo bioluminescence imaging approach to monitor the kinetics of SARS-CoV-2 spread and clearance in real time in vivo. We have assembled a team of investigators with extensive experience in 1) creating new humanized mouse strains (Dr. Leonard Shultz at The Jackson Laboratory), 2) engrafting human immune systems into immunodeficient mice (Drs. Dale Greiner and Michael Brehm at UMass), 3) the study of human viral pathogens (Dr. Priti Kumar at Yale University), and 4) expertise in imaging virus infection in real time in vivo (Dr. Pradeep Uchil at Yale University). We will leverage the resources of The Jackson Laboratory to facilitate the rapid distribution of effective models to the scientific community, uniquely positioning our group to contribute quickly to the knowledge of SARS-CoV-2 biology. Dr. Shultz has generated new models of NSG mice expressing human ACE2 and will provide these mice to Dr. Kumar and to Drs. Brehm and Greiner. Drs. Brehm and Greiner will engraft the mice with human UCB CD34+ HSCs and will provide engrafted mice to Dr. Kumar's laboratory. Drs. Kumar and Uchil will perform the infection studies with SARS-CoV-2 and its variants in both non-human immune engrafted (Specific Aim 1) and human immune engrafted mice (Specific Aim 2) and analyze the kinetics of virus clearance in real time using novel bioluminescent imaging technology. In addition, overall mouse health, viral load in tissues and inflammatory cytokines will be monitored. We will validate the optimal SARS-CoV-2 infection protocols with the NSG mouse stocks. Ultimately, these studies will determine the clearance and pathogenesis of SARS-CoV-2 and variants in the absence or presence of a human immune system.