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All coronaviruses known to have recently emerged as human pathogens probably originated in bats.sup.1. Here we use a single experimental platform based on immunodeficient mice implanted with human lung tissue (hereafter, human lung-only mice (LoM)) to demonstrate the efficient in vivo replication of severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as well as two endogenous SARS-like bat coronaviruses that show potential for emergence as human pathogens. Virus replication in this model occurs in bona fide human lung tissue and does not require any type of adaptation of the virus or the host. Our results indicate that bats contain endogenous coronaviruses that are capable of direct transmission to humans. Our detailed analysis of in vivo infection with SARS-CoV-2 in human lung tissue from LoM showed a predominant infection of human lung epithelial cells, including type-2 pneumocytes that are present in alveoli and ciliated airway cells. Acute infection with SARS-CoV-2 was highly cytopathic and induced a robust and sustained type-I interferon and inflammatory cytokine and chemokine response. Finally, we evaluated a therapeutic and pre-exposure prophylaxis strategy for SARS-CoV-2 infection. Our results show that therapeutic and prophylactic administration of EIDD-2801--an oral broad-spectrum antiviral agent that is currently in phase II/III clinical trials--markedly inhibited SARS-CoV-2 replication in vivo, and thus has considerable potential for the prevention and treatment of COVID-19. Human and bat coronaviruses replicate efficiently in immunodeficient mice implanted with human lung tissue, and treatment or prophylaxis using EIDD-2801 in this model suggests that this oral antiviral agent may be effective in preventing COVID-19., Author(s): Angela Wahl [sup.1] [sup.2] [sup.3] , Lisa E. Gralinski [sup.4] , Claire E. Johnson [sup.1] [sup.2] [sup.3] , Wenbo Yao [sup.1] [sup.2] [sup.3] , Martina Kovarova [sup.1] [sup.2] [sup.3] [...]

Coronaviruses are prone to transmission to new host species, as recently demonstrated by the spread to humans of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19) pandemic.sup.1. Small animal models that recapitulate SARS-CoV-2 disease are needed urgently for rapid evaluation of medical countermeasures.sup.2,3. SARS-CoV-2 cannot infect wild-type laboratory mice owing to inefficient interactions between the viral spike protein and the mouse orthologue of the human receptor, angiotensin-converting enzyme 2 (ACE2).sup.4. Here we used reverse genetics.sup.5 to remodel the interaction between SARS-CoV-2 spike protein and mouse ACE2 and designed mouse-adapted SARS-CoV-2 (SARS-CoV-2 MA), a recombinant virus that can use mouse ACE2 for entry into cells. SARS-CoV-2 MA was able to replicate in the upper and lower airways of both young adult and aged BALB/c mice. SARS-CoV-2 MA caused more severe disease in aged mice, and exhibited more clinically relevant phenotypes than those seen in Hfh4-ACE2 transgenic mice, which express human ACE2 under the control of the Hfh4 (also known as Foxj1) promoter. We demonstrate the utility of this model using vaccine-challenge studies in immune-competent mice with native expression of mouse ACE2. Finally, we show that the clinical candidate interferon-[lambda]1a (IFN-[lambda]1a) potently inhibits SARS-CoV-2 replication in primary human airway epithelial cells in vitro--both prophylactic and therapeutic administration of IFN-[lambda]1a diminished SARS-CoV-2 replication in mice. In summary, the mouse-adapted SARS-CoV-2 MA model demonstrates age-related disease pathogenesis and supports the clinical use of pegylated IFN-[lambda]1a as a treatment for human COVID-19.sup.6. A model in mouse using a species-adapted virus recapitulates features of SARS-CoV-2 infection and age-related disease pathogenesis in humans, and provides a model system for rapid evaluation of medical countermeasures against coronavirus disease 2019 (COVID-19)., Author(s): Kenneth H. Dinnon III [sup.1] , Sarah R. Leist [sup.2] , Alexandra Schäfer [sup.2] , Caitlin E. Edwards [sup.2] , David R. Martinez [sup.2] , Stephanie A. Montgomery [sup.3] [...]

Zika virus (ZIKV) is a mosquito-borne positive sense RNA virus. Recently, ZIKV emerged into the Western hemisphere as a human health threat, with severe disease associated with developmental and neurological complications. The structural envelope protein of ZIKV and other neurotropic flaviviruses contains an extended CD-loop relative to non-neurotropic flaviviruses, and has been shown to augment ZIKV stability and pathogenesis. Here we show that shortening the CD-loop in ZIKV attenuates the virus in mice, by reducing the ability to invade and replicate in the central nervous system. The CD-loop mutation was genetically stable following infection in mice, though secondary site mutations arise adjacent to the CD-loop. Importantly, while shortening of the CD-loop attenuates the virus, the CD-loop mutant maintains antigenicity in immunocompetent mice, eliciting an antibody response that similarly neutralizes both the mutant and wildtype ZIKV. These findings suggest that the extended CD-loop in ZIKV is a determinant of neurotropism and may be a target in live-attenuated vaccine design, for not only ZIKV, but for other neurotropic flaviviruses. [ABSTRACT FROM AUTHOR]

Background: Prostate ductal branching morphogenesis involves a complex spatiotemporal regulation of cellular proliferation and remodeling of the extracellular matrix (ECM) around the developing ducts. Decorin (Dcn) is a small leucine‐rich proteoglycan known to sequester several growth factors and to act as a tumor suppressor in prostate cancer. Results:Dcn expression in the developing prostate paralleled branching morphogenesis and was dynamically regulated by androgen and Hedgehog (Hh) signaling. DCN colocalized with collagen in the periductal stroma and acellular interstitium. Exogenous DCN decreased epithelial proliferation in ex vivo organ cultures of developing prostate, whereas genetic ablation of Dcn resulted in increased epithelial proliferation in the developing prostate. Conclusions:Dcn expression and localization in the developing prostate is consistent with a primary role in organizing collagen around the developing ducts. Regulation of Dcn expression appears to be complex, involving both androgen and Hh signaling. The growth inhibitory effect of Dcn suggests a unique linkage between a structural proteoglycan and epithelial growth regulation. This may serve to coordinate two elements of the morphogenetic process: ductal growth and organization of the collagen matrix around the nascent duct. Developmental Dynamics 247:679–685, 2018. © 2018 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The global COVID-19 pandemic has sparked intense interest in the rapid development of vaccines as well as animal models to evaluate vaccine candidates and to define immune correlates of protection. We recently reported a mouse-adapted SARS-CoV-2 virus strain (MA10) with the potential to infect wild-type laboratory mice, driving high levels of viral replication in respiratory tract tissues as well as severe clinical and respiratory symptoms, aspects of COVID-19 disease in humans that are important to capture in model systems. We evaluated the immunogenicity and protective efficacy of novel rhesus adenovirus serotype 52 (RhAd52) vaccines against MA10 challenge in mice. Baseline seroprevalence is lower for rhesus adenovirus vectors than for human or chimpanzee adenovirus vectors, making these vectors attractive candidates for vaccine development. We observed that RhAd52 vaccines elicited robust binding and neutralizing antibody titers, which inversely correlated with viral replication after challenge. These data support the development of RhAd52 vaccines and the use of the MA10 challenge virus to screen novel vaccine candidates and to study the immunologic mechanisms that underscore protection from SARS-CoV-2 challenge in wild-type mice. IMPORTANCE We have developed a series of SARS-CoV-2 vaccines using rhesus adenovirus serotype 52 (RhAd52) vectors, which exhibit a lower seroprevalence than human and chimpanzee vectors, supporting their development as novel vaccine vectors or as an alternative adenovirus (Ad) vector for boosting. We sought to test these vaccines using a recently reported mouse-adapted SARS-CoV-2 (MA10) virus to (i) evaluate the protective efficacy of RhAd52 vaccines and (ii) further characterize this mouse-adapted challenge model and probe immune correlates of protection. We demonstrate that RhAd52 vaccines elicit robust SARS-CoV-2-specific antibody responses and protect against clinical disease and viral replication in the lungs. Further, binding and neutralizing antibody titers correlated with protective efficacy. These data validate the MA10 mouse model as a useful tool to screen and study novel vaccine candidates, as well as the development of RhAd52 vaccines for COVID-19. [ABSTRACT FROM AUTHOR]