• Abelson kinase inhibitors are potent inhibitors of severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus fusion

      Coleman, C.M.; Sisk, J.M.; Frieman, M.B. (American Society for Microbiology, 2016)
      The highly pathogenic severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) cause significant morbidity and morality. There is currently no approved therapeutic for highly pathogenic coronaviruses, even as MERS-CoV is spreading throughout the Middle East. We previously screened a library of FDA-approved drugs for inhibitors of coronavirus replication in which we identified Abelson (Abl) kinase inhibitors, including the anticancer drug imatinib, as inhibitors of both SARS-CoV and MERS-CoV in vitro. Here we show that the anti-CoV activity of imatinib occurs at the early stages of infection, after internalization and endosomal trafficking, by inhibiting fusion of the virions at the endosomal membrane. We specifically identified the imatinib target, Abelson tyrosine-protein kinase 2 (Abl2), as required for efficient SARS-CoV and MERS-CoV replication in vitro. These data demonstrate that specific approved drugs can be characterized in vitro for their anticoronavirus activity and used to identify host proteins required for coronavirus replication. This type of study is an important step in the repurposing of approved drugs for treatment of emerging coronaviruses.
    • The art of war: Battles between virus and host

      Frieman, M. (Elsevier B.V., 2014)
    • Coronavirus S protein-induced fusion is blocked prior to hemifusion by Abl kinase inhibitors

      Sisk, J.M.; Frieman, M.B.; Machamer, C.E. (Microbiology Society, 2018)
      Enveloped viruses gain entry into host cells by fusing with cellular membranes, a step that is required for virus replication. Coronaviruses, including the severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and infectious bronchitis virus (IBV), fuse at the plasma membrane or use receptor-mediated endocytosis and fuse with endosomes, depending on the cell or tissue type. The virus spike (S) protein mediates fusion with the host cell membrane. We have shown previously that an Abelson (Abl) kinase inhibitor, imatinib, significantly reduces SARS-CoV and MERS-CoV viral titres and prevents endosomal entry by HIV SARS S and MERS S pseudotyped virions. SARSCoV and MERS-CoV are classified as BSL-3 viruses, which makes experimentation into the cellular mechanisms involved in infection more challenging. Here, we use IBV, a BSL-2 virus, as a model for studying the role of Abl kinase activity during coronavirus infection. We found that imatinib and two specific Abl kinase inhibitors, GNF2 and GNF5, reduce IBV titres by blocking the first round of virus infection. Additionally, all three drugs prevented IBV S-induced syncytia formation prior to the hemifusion step. Our results indicate that membrane fusion (both virus-cell and cell-cell) is blocked in the presence of Abl kinase inhibitors. Studying the effects of Abl kinase inhibitors on IBV will be useful in identifying the host cell pathways required for coronavirus infection. This will provide an insight into possible therapeutic targets to treat infections by current as well as newly emerging coronaviruses. Copyright 2018 The Authors.
    • Coronaviruses: Important emerging human pathogens

      Coleman, C.M.; Frieman, M.B. (American Society for Microbiology, 2014)
      The identification of Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 reaffirmed the importance of understanding how coronaviruses emerge, infect, and cause disease. By comparing what is known about severe acute respiratory syndrome coronavirus (SARS-CoV) to what has recently been found for MERS-CoV, researchers are discovering similarities and differences that may be important for pathogenesis. Here we discuss what is known about each virus and what gaps remain in our understanding, especially concerning MERS-CoV.
    • Emergence of the Middle East Respiratory Syndrome Coronavirus

      Coleman, C.M.; Frieman, M.B. (Public Library of Science, 2013-09-05)
    • Evaluation of SSYA10-001 as a replication inhibitor of severe acute respiratory syndrome, mouse hepatitis, and Middle East respiratory syndrome coronaviruses

      Adedeji, A.O.; Singh, K.; Coleman, C.M. (American Society for Microbiology, 2014)
      We have previously shown that SSYA10-001 blocks severe acute respiratory syndrome coronavirus (SARS-CoV) replication by inhibiting SARS-CoV helicase (nsp13). Here, we show that SSYA10-001 also inhibits replication of two other coronaviruses, mouse hepatitis virus (MHV) and Middle Eastern respiratory syndrome coronavirus (MERS-CoV). A putative binding pocket for SSYA10-001 was identified and shown to be similar in SARS-CoV, MERS-CoV, and MHV helicases. These studies show that it is possible to target multiple coronaviruses through broad-spectrum inhibitors.
    • Genome Wide Identification of SARS-CoV Susceptibility Loci Using the Collaborative Cross

      Gralinski, L.E.; Ferris, M.T.; Frieman, M.B. (Public Library of Science, 2015)
      New systems genetics approaches are needed to rapidly identify host genes and genetic networks that regulate complex disease outcomes. Using genetically diverse animals from incipient lines of the Collaborative Cross mouse panel, we demonstrate a greatly expanded range of phenotypes relative to classical mouse models of SARS-CoV infection including lung pathology, weight loss and viral titer. Genetic mapping revealed several loci contributing to differential disease responses, including an 8.5Mb locus associated with vascular cuffing on chromosome 3 that contained 23 genes and 13 noncoding RNAs. Integrating phenotypic and genetic data narrowed this region to a single gene, Trim55, an E3 ubiquitin ligase with a role in muscle fiber maintenance. Lung pathology and transcriptomic data from mice genetically deficient in Trim55 were used to validate its role in SARS-CoV-induced vascular cuffing and inflammation. These data establish the Collaborative Cross platform as a powerful genetic resource for uncovering genetic contributions of complex traits in microbial disease severity, inflammation and virus replication in models of outbred populations.
    • Induction of alternatively activated macrophages enhances pathogenesis during severe acute respiratory syndrome coronavirus infection

      Page, C.; Goicochea, L.; Matthews, K.; Frieman, M. (2012)
      Infection with severe acute respiratory syndrome coronavirus (SARS-CoV) causes acute lung injury (ALI) that often leads to severe lung disease. A mouse model of acute SARS-CoV infection has been helpful in understanding the host response to infection; however, there are still unanswered questions concerning SARS-CoV pathogenesis. We have shown that STAT1 plays an important role in the severity of SARS-CoV pathogenesis and that it is independent of the role of STAT1 in interferon signaling. Mice lacking STAT1 have greater weight loss, severe lung pathology with pre-pulmonary-fibrosis-like lesions, and an altered immune response following infection with SARS-CoV. We hypothesized that STAT1 plays a role in the polarization of the immune response, specifically in macrophages, resulting in a worsened outcome. To test this, we created bone marrow chimeras and celltype- specific knockouts of STAT1 to identify which cell type(s) is critical to protection from severe lung disease after SARS-CoV infection. Bone marrow chimera experiments demonstrated that hematopoietic cells are responsible for the pathogenesis in STAT1-/- mice, and because of an induction of alternatively activated (AA) macrophages after infection, we hypothesized that the AA macrophages were critical for disease severity. Mice with STAT1 in either monocytes and macrophages (LysM/STAT1) or ciliated lung epithelial cells (FoxJ1/STAT1) deleted were created. Following infection, LysM/STAT1 mice display severe lung pathology, while FoxJ1/STAT1 mice display normal lung pathology. We hypothesized that AA macrophages were responsible for this STAT1-dependent pathology and therefore created STAT1/STAT6-/- double-knockout mice. STAT6 is essential for the development of AA macrophages. Infection of the double-knockout mice displayed a lack of lung disease and prefibrotic lesions, suggesting that AA macrophage production may be the cause of STAT1-dependent lung disease. We propose that the control of AA macrophages by STAT1 is critical to regulating immune pathologies and for protection from long-term progression to fibrotic lung disease in a mouse model of SARS-CoV infection.
    • Integrative deep sequencing of the mouse lung transcriptome reveals differential expression of diverse classes of small RNAs in response to respiratory virus infection

      Peng, X.; Gralinski, L.; Frieman, M.B. (2011)
      We previously reported widespread differential expression of long non-protein-coding RNAs (ncRNAs) in response to virus infection. Here, we expanded the study through small RNA transcriptome sequencing analysis of the host response to both severe acute respiratory syndrome coronavirus (SARS-CoV) and influenza virus infections across four founder mouse strains of the Collaborative Cross, a recombinant inbred mouse resource for mapping complex traits. We observed differential expression of over 200 small RNAs of diverse classes during infection. A majority of identified microRNAs (miRNAs) showed divergent changes in expression across mouse strains with respect to SARS-CoV and influenza virus infections and responded differently to a highly pathogenic reconstructed 1918 virus compared to a minimally pathogenic seasonal influenza virus isolate. Novel insights into miRNA expression changes, including the association with pathogenic outcomes and large differences between in vivo and in vitro experimental systems, were further elucidated by a survey of selected miRNAs across diverse virus infections. The small RNAs identified also included many non-miRNA small RNAs, such as small nucleolar RNAs (snoRNAs), in addition to nonannotated small RNAs. An integrative sequencing analysis of both small RNAs and long transcripts from the same samples showed that the results revealing differential expression of miRNAs during infection were largely due to transcriptional regulation and that the predicted miRNA-mRNA network could modulate global host responses to virus infection in a combinatorial fashion. These findings represent the first integrated sequencing analysis of the response of host small RNAs to virus infection and show that small RNAs are an integrated component of complex networks involved in regulating the host response to infection. Copyright 2011 Peng et al.
    • Inverse correlation between average monthly high temperatures and COVID-19-related death rates in different geographical areas

      Benedetti, F.; Zella, D.; Gallo. R.C. (Springer Nature, 2020)
      Background With the aim of providing a dynamic evaluation of the effects of basic environmental parameters on COVID-19-related death rate, we assessed the correlation between average monthly high temperatures and population density, with death/rate (monthly number of deaths/1 M people) for the months of March (start of the analysis and beginning of local epidemic in most of the Western World, except in Italy where it started in February) and April 2020 (continuation of the epidemic). Different geographical areas of the Northern Hemisphere in the United States and in Europe were selected in order to provide a wide range among the different parameters. The death rates were gathered from an available dataset. As a further control, we also included latitude, as a proxy for temperature. Methods Utilizing a publicly available dataset, we retrieved data for the months of March and April 2020 for 25 areas in Europe and in the US. We computed the monthly number of deaths/1 M people of confirmed COVID-19 cases and calculated the average monthly high temperatures and population density for all these areas. We determined the correlation between number of deaths/1 M people and the average monthly high temperatures, the latitude and the population density. Results We divided our analysis in two parts: analysis of the correlation among the different variables in the month of March and subsequent analysis in the month of April. The differences were then evaluated. In the month of March there was no statistical correlation between average monthly high temperatures of the considered geographical areas and number of deaths/1 M people. However, a statistically significant inverse correlation became significant in the month of April between average monthly high temperatures (p = 0.0043) and latitude (p = 0.0253) with number of deaths/1 M people. We also observed a statistically significant correlation between population density and number of deaths/1 M people both in the month of March (p = 0.0297) and in the month of April (p = 0.0116), when three areas extremely populated (NYC, Los Angeles and Washington DC) were included in the calculation. Once these three areas were removed, the correlation was not statistically significant (p = 0.1695 in the month of March, and p = 0.7076 in the month of April). Conclusions The number of COVID-19-related deaths/1 M people was essentially the same during the month of March for all the geographical areas considered, indicating essentially that the infection was circulating quite uniformly except for Lombardy, Italy, where it started earlier. Lockdown measures were implemented between the end of March and beginning of April, except for Italy which started March 9th. We observed a strong, statistically significant inverse correlation between average monthly high temperatures with the number of deaths/1 M people. We confirmed the data by analyzing the correlation with the latitude, which can be considered a proxy for high temperature. Previous studies indicated a negative effect of high climate temperatures on Sars-COV-2 spreading. Our data indicate that social distancing measure are more successful in the presence of higher average monthly temperatures in reducing COVID-19-related death rate, and a high level of population density seems to negatively impact the effect of lockdown measures.
    • Molecular determinants of severe acute respiratory syndrome coronavirus pathogenesis and virulence in young and aged mouse models of human disease

      Frieman, M.; Yount, B.; Page, C. (2012)
      SARS coronavirus (SARS-CoV) causes severe acute respiratory tract disease characterized by diffuse alveolar damage and hyaline membrane formation. This pathology often progresses to acute respiratory distress (such as acute respiratory distress syndrome [ARDS]) and atypical pneumonia in humans, with characteristic age-related mortality rates approaching 50% or more in immunosenescent populations. The molecular basis for the extreme virulence of SARS-CoV remains elusive. Since young and aged (1-year-old) mice do not develop severe clinical disease following infection with wild-type SARS-CoV, a mouse-adapted strain of SARS-CoV (called MA15) was developed and was shown to cause lethal infection in these animals. To understand the genetic contributions to the increased pathogenesis of MA15 in rodents, we used reverse genetics and evaluated the virulence of panels of derivative viruses encoding various combinations of mouse-adapted mutations. We found that mutations in the viral spike (S) glycoprotein and, to a much less rigorous extent, in the nsp9 nonstructural protein, were primarily associated with the acquisition of virulence in young animals. The mutations in S likely increase recognition of the mouse angiotensin-converting enzyme 2 (ACE2) receptor not only in MA15 but also in two additional, independently isolated mouse-adapted SARS-CoVs. In contrast to the findings for young animals, mutations to revert to the wild-type sequence in nsp9 and the S glycoprotein were not sufficient to significantly attenuate the virus compared to other combinations of mouse-adapted mutations in 12-month-old mice. This panel of SARS-CoVs provides novel reagents that we have used to further our understanding of differential, age-related pathogenic mechanisms in mouse models of human disease.
    • The ORF4b-encoded accessory proteins of Middle East respiratory syndrome coronavirus and two related bat coronaviruses localize to the nucleus and inhibit innate immune signalling

      Matthews, K.L.; Coleman, C.M.; Frieman, M.B. (Society for General Microbiology, 2014)
      The recently emerged Middle East respiratory syndrome coronavirus (MERS-CoV), a betacoronavirus, is associated with severe pneumonia and renal failure. The environmental origin of MERS-CoV is as yet unknown; however, its genome sequence is closely related to those of two bat coronaviruses, named BtCoV-HKU4 and BtCoV-HKU5, which were derived from Chinese bat samples. A hallmark of highly pathogenic respiratory viruses is their ability to evade the innate immune response of the host. CoV accessory proteins, for example those from severe acute respiratory syndrome CoV (SARS-CoV), have been shown to block innate antiviral signalling pathways. MERS-CoV, similar to SARS-CoV, has been shown to inhibit type I IFN induction in a variety of cell types in vitro. We therefore hypothesized that MERS-CoV and the phylogenetically related BtCoV-HKU4 and BtCoV-HKU5 may encode proteins with similar capabilities. In this study, we have demonstrated that the ORF4b-encoded accessory protein (p4b) of MERS-CoV, BtCoV-HKU4 and BtCoV-HKU5 may indeed facilitate innate immune evasion by inhibiting the type I IFN and NF-κB signalling pathways. We also analysed the subcellular localization of p4b from MERS-CoV, BtCoV-HKU4 and BtCoV-HKU5 and demonstrated that all are localized to the nucleus.
    • Overactive epidermal growth factor receptor signaling leads to increased fibrosis after severe acute respiratory syndrome coronavirus infection

      Venkataraman, T.; Coleman, C.M.; Frieman, M.B. (American Society for Microbiology, 2017)
      Severe acute respiratory syndrome coronavirus (SARS-CoV) is a highly pathogenic respiratory virus that causes morbidity and mortality in humans. After infection with SARS-CoV, the acute lung injury caused by the virus must be repaired to regain lung function. A dysregulation in this wound healing process leads to fibrosis. Many survivors of SARS-CoV infection develop pulmonary fibrosis (PF), with higher prevalence in older patients. Using mouse models of SARS-CoV pathogenesis, we have identified that the wound repair pathway, controlled by the epidermal growth factor receptor (EGFR), is critical to recovery from SARS-CoV-induced tissue damage. In mice with constitutively active EGFR [EGFR(DSK5) mice], we find that SARS-CoV infection causes enhanced lung disease. Importantly, we show that during infection, the EGFR ligands amphiregulin and heparin-binding EGF-like growth factor (HB-EGF) are upregulated, and exogenous addition of these ligands during infection leads to enhanced lung disease and altered wound healing dynamics. Our data demonstrate a key role of EGFR in the host response to SARS-CoV and how it may be implicated in lung disease induced by other highly pathogenic respiratory viruses.
    • Purified coronavirus spike protein nanoparticles induce coronavirus neutralizing antibodies in mice

      Coleman, C.M.; Taylor, J.K.; Frieman, M.B. (Elsevier Ltd, 2014)
      Development of vaccination strategies for emerging pathogens are particularly challenging because of the sudden nature of their emergence and the long process needed for traditional vaccine development. Therefore, there is a need for development of a rapid method of vaccine development that can respond to emerging pathogens in a short time frame.The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in late 2012 demonstrate the importance of coronaviruses as emerging pathogens. The spike glycoproteins of coronaviruses reside on the surface of the virion and are responsible for virus entry. The spike glycoprotein is the major immunodominant antigen of coronaviruses and has proven to be an excellent target for vaccine designs that seek to block coronavirus entry and promote antibody targeting of infected cells.Vaccination strategies for coronaviruses have involved live attenuated virus, recombinant viruses, non-replicative virus-like particles expressing coronavirus proteins or DNA plasmids expressing coronavirus genes. None of these strategies has progressed to an approved human coronavirus vaccine in the ten years since SARS-CoV emerged. Here we describe a novel method for generating MERS-CoV and SARS-CoV full-length spike nanoparticles, which in combination with adjuvants are able to produce high titer antibodies in mice.
    • Repurposing of clinically developed drugs for treatment of Middle East respiratory syndrome coronavirus infection

      Coleman, C.M.; Venkataraman, T.; Frieman, M.B. (American Society for Microbiology, 2014)
      Outbreaks of emerging infections present health professionals with the unique challenge of trying to select appropriate pharmacologic treatments in the clinic with little time available for drug testing and development. Typically, clinicians are left with general supportive care and often untested convalescent-phase plasma as available treatment options. Repurposing of approved pharmaceutical drugs for new indications presents an attractive alternative to clinicians, researchers, public health agencies, drug developers, and funding agencies. Given the development times and manufacturing requirements for new products, repurposing of existing drugs is likely the only solution for outbreaks due to emerging viruses. In the studies described here, a library of 290 compounds was screened for antiviral activity against Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus (SARS-CoV). Selection of compounds for inclusion in the library was dependent on current or previous FDA approval or advanced clinical development. Some drugs that had a well-defined cellular pathway as target were included. In total, 27 compounds with activity against both MERS-CoV and SARS-CoV were identified. The compounds belong to 13 different classes of pharmaceuticals, including inhibitors of estrogen receptors used for cancer treatment and inhibitors of dopamine receptor used as antipsychotics. The drugs identified in these screens provide new targets for in vivo studies as well as incorporation into ongoing clinical studies.
    • The role of epidermal growth factor receptor (EGFR) signaling in SARS coronavirus-induced pulmonary fibrosis

      Venkataraman, T.; Frieman, M.B. (Elsevier B.V., 2017)
      Many survivors of the 2003 outbreak of severe acute respiratory syndrome (SARS) developed residual pulmonary fibrosis with increased severity seen in older patients. Autopsies of patients that died from SARS also showed fibrosis to varying extents. Pulmonary fibrosis can be occasionally seen as a consequence to several respiratory viral infections but is much more common after a SARS coronavirus (SARS-CoV) infection. Given the threat of future outbreaks of severe coronavirus disease, including Middle East respiratory syndrome (MERS), it is important to understand the mechanisms responsible for pulmonary fibrosis, so as to support the development of therapeutic countermeasures and mitigate sequelae of infection. In this article, we summarize pulmonary fibrotic changes observed after a SARS-CoV infection, discuss the extent to which other respiratory viruses induce fibrosis, describe available animal models to study the development of SARS-CoV induced fibrosis and review evidence that pulmonary fibrosis is caused by a hyperactive host response to lung injury mediated by epidermal growth factor receptor (EGFR) signaling. We summarize work from our group and others indicating that inhibiting EGFR signaling may prevent an excessive fibrotic response to SARS-CoV and other respiratory viral infections and propose directions for future research.
    • SARS-CoV attack (severe acute respiratory syndrome)

      Freeman, D.; Kenez, E. (Elsevier Inc., 2016)
    • Severe acute respiratory syndrome coronavirus ORF7a inhibits bone marrow stromal antigen 2 virion tethering through a novel mechanism of glycosylation interference

      Taylor, J.K.; Coleman, C.M.; Postel, S.; Sisk, J.M.; Venkataraman, T.; Sundberg, E.J.; Frieman, M.B. (American Society for Microbiology, 2015)
      Severe acute respiratory syndrome (SARS) emerged in November 2002 as a case of atypical pneumonia in China, and the causative agent of SARS was identified to be a novel coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV). Bone marrow stromal antigen 2 (BST-2; also known as CD317 or tetherin) was initially identified to be a pre-B-cell growth promoter, but it also inhibits the release of virions of the retrovirus human immunodeficiency virus type 1 (HIV-1) by tethering budding virions to the host cell membrane. Further work has shown that BST-2 restricts the release of many other viruses, including the human coronavirus 229E (hCoV-229E), and the genomes of many of these viruses encode BST-2 antagonists to overcome BST-2 restriction. Given the previous studies on BST-2, we aimed to determine if BST-2 has the ability to restrict SARS-CoV and if the SARS-CoV genome encodes any proteins that modulate BST-2's antiviral function. Through an in vitro screen, we identified four potential BST-2 modulators encoded by the SARS-CoV genome: the papain-like protease (PLPro), nonstructural protein 1 (nsp1), ORF6, and ORF7a. As the function of ORF7a in SARS-CoV replication was previously unknown, we focused our study on ORF7a. We found that BST-2 does restrict SARS-CoV, but the loss of ORF7a leads to a much greater restriction, confirming the role of ORF7a as an inhibitor of BST-2. We further characterized the mechanism of BST-2 inhibition by ORF7a and found that ORF7a localization changes when BST-2 is overexpressed and ORF7a binds directly to BST-2. Finally, we also show that SARSCoV ORF7a blocks the restriction activity of BST-2 by blocking the glycosylation of BST-2.
    • Targeting N-glycan cryptic sugar moieties for broad-spectrum virus neutralization: Progress in identifying conserved molecular targets in viruses of distinct phylogenetic origins

      Wang, D.; Tang, J.; Wang, L.-X. (MDPI AG, 2015)
      Identifying molecular targets for eliciting broadly virus-neutralizing antibodies is one of the key steps toward development of vaccines against emerging viral pathogens. Owing to genomic and somatic diversities among viral species, identifying protein targets for broad-spectrum virus neutralization is highly challenging even for the same virus, such as HIV-1. However, viruses rely on host glycosylation machineries to synthesize and express glycans and, thereby, may display common carbohydrate moieties. Thus, exploring glycan-binding profiles of broad-spectrum virus-neutralizing agents may provide key information to uncover the carbohydrate-based virus-neutralizing epitopes. In this study, we characterized two broadly HIV-neutralizing agents, human monoclonal antibody 2G12 and Galanthus nivalis lectin (GNA), for their viral targeting activities. Although these agents were known to be specific for oligomannosyl antigens, they differ strikingly in virus-binding activities. The former is HIV-1 specific; the latter is broadly reactive and is able to neutralize viruses of distinct phylogenetic origins, such as HIV-1, severe acute respiratory syndrome coronavirus (SARS-CoV), and human cytomegalovirus (HCMV). In carbohydrate microarray analyses, we explored the molecular basis underlying the striking differences in the spectrum of anti-virus activities of the two probes. Unlike 2G12, which is strictly specific for the high-density Man<inf>9</inf>GlcNAc<inf>2</inf>Asn (Man9)-clusters, GNA recognizes a number of N-glycan cryptic sugar moieties. These include not only the known oligomannosyl antigens but also previously unrecognized tri-antennary or multi-valent GlcNAc-terminating N-glycan epitopes (Tri/m-Gn). These findings highlight the potential of N-glycan cryptic sugar moieties as conserved targets for broad-spectrum virus neutralization and suggest the GNA-model of glycan-binding warrants focused investigation. Copyright 2015 by the authors.
    • Transcriptomic analysis reveals a mechanism for a prefibrotic phenotype in STAT1 knockout mice during severe acute respiratory syndrome coronavirus infection

      Zornetzer, G.A.; Frieman, M.B.; Rosenzweig, E. (American Society for Microbiology, 2010)
      Severe acute respiratory syndrome coronavirus (SARS-CoV) infection can cause the development of severe end-stage lung disease characterized by acute respiratory distress syndrome (ARDS) and pulmonary fibrosis. The mechanisms by which pulmonary lesions and fibrosis are generated during SARS-CoV infection are not known. Using high-throughput mRNA profiling, we examined the transcriptional response of wild-type (WT), type I interferon receptor knockout (IFNAR1-/-), and STAT1 knockout (STAT1-/-) mice infected with a recombinant mouse-adapted SARS-CoV (rMA15) to better understand the contribution of specific gene expression changes to disease progression. Despite a deletion of the type I interferon receptor, strong expression of interferon-stimulated genes was observed in the lungs of IFNAR1-/- mice, contributing to clearance of the virus. In contrast, STAT1-/- mice exhibited a defect in the expression of interferon-stimulated genes and were unable to clear the infection, resulting in a lethal outcome. STAT1 -/- mice exhibited dysregulation of T-cell and macrophage differentiation, leading to a TH2-biased immune response and the development of alternatively activated macrophages that mediate a profibrotic environment within the lung. We propose that a combination of impaired viral clearance and T-cell/macrophage dysregulation causes the formation of prefibrotic lesions in the lungs of rMA15-infected STAT1-/- mice.