SARS-like WIV1-CoV poised for human emergence Menachery, Vineet D.; Yount, Boyd L.; Sims, Amy C. ...
Proceedings of the National Academy of Sciences - PNAS,
03/2016, Letnik:
113, Številka:
11
Journal Article
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Outbreaks from zoonotic sources represent a threat to both human disease as well as the global economy. Despite a wealth of metagenomics studies,methods to leverage these datasets to identify future ...threats are underdeveloped. In this study, we describe an approach that combines existing metagenomics data with reverse genetics to engineer reagents to evaluate emergence and pathogenic potential of circulating zoonotic viruses. Focusing on the severe acute respiratory syndrome (SARS)-like viruses, the results indicate that the WIV1-coronavirus (CoV) cluster has the ability to directly infect and may undergo limited transmission in human populations. However, in vivo attenuation suggests additional adaptation is required for epidemic disease. Importantly, available SARS monoclonal antibodies offered success in limiting viral infection absent from available vaccine approaches. Together, the data highlight the utility of a platform to identify and prioritize prepandemic strains harbored in animal reservoirs and document the threat posed by WIV1-CoV for emergence in human populations.
All coronaviruses known to have recently emerged as human pathogens probably originated in bats
. 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.
The nucleotide-binding domain and leucine-rich-repeat-containing (NLR) family of pattern-recognition molecules mediate host immunity to various pathogenic stimuli. However, in vivo evidence for the ...involvement of NLR proteins in viral sensing has not been widely investigated and remains controversial. As a test of the physiologic role of the NLR molecule NLRP3 during RNA viral infection, we explored the in vivo role of NLRP3 inflammasome components during influenza virus infection. Mice lacking Nlrp3, Pycard, or caspase-1, but not Nlrc4, exhibited dramatically increased mortality and a reduced immune response after exposure to the influenza virus. Utilizing analogs of dsRNA (poly(I:C)) and ssRNA (ssRNA40), we demonstrated that an NLRP3-mediated response could be activated by RNA species. Mechanistically, NLRP3 inflammasome activation by the influenza virus was dependent on lysosomal maturation and reactive oxygen species (ROS). Inhibition of ROS induction eliminated IL-1β production in animals during influenza infection. Together, these data place the NLRP3 inflammasome as an essential component in host defense against influenza infection through the sensing of viral RNA.
Vitamin D has been linked to reduced risk of viral respiratory illness. We hypothesized that vitamin D could directly reduce rhinovirus (RV) replication in airway epithelium. Primary human bronchial ...epithelial cells (hBEC) were treated with vitamin D, and RV replication and gene expression were evaluated by quantitative PCR. Cytokine/chemokine secretion was measured by ELISA, and transepithelial resistance (TER) was determined using a voltohmmeter. Morphology was examined using immunohistochemistry. Vitamin D supplementation had no significant effects on RV replication, but potentiated secretion of CXCL8 and CXCL10 from infected or uninfected cells. Treatment with vitamin D in the form of 1,25(OH)2D caused significant changes in cell morphology, including thickening of the cell layers (median of 46.5 µm 35.0-69.0 vs. 30 µm 24.5-34.2, p<0.01) and proliferation of cytokeratin-5-expressing cells, as demonstrated by immunohistochemical analysis. Similar effects were seen for 25(OH)D. In addition to altering morphology, higher concentrations of vitamin D significantly upregulated small proline-rich protein (SPRR1β) expression (6.3 fold-induction, p<0.01), suggestive of squamous metaplasia. Vitamin D treatment of hBECs did not alter repair of mechanically induced wounds. Collectively, these findings indicate that vitamin D does not directly affect RV replication in airway epithelial cells, but can influence chemokine synthesis and alters the growth and differentiation of airway epithelial cells.
Dysfunction of CFTR in cystic fibrosis (CF) airway epithelium perturbs the normal regulation of ion transport, leading to a reduced volume of airway surface liquid (ASL), mucus dehydration, decreased ...mucus transport, and mucus plugging of the airways. CFTR is normally expressed in ciliated epithelial cells of the surface and submucosal gland ductal epithelium and submucosal gland acinar cells. Critical questions for the development of gene transfer strategies for CF airway disease are what airway regions require CFTR function and how many epithelial cells require CFTR expression to restore normal ASL volume regulation and mucus transport to CF airway epithelium? An in vitro model of human CF ciliated surface airway epithelium (CF HAE) was used to test whether a human parainfluenza virus (PIV) vector engineered to express CFTR (PIVCFTR) could deliver sufficient CFTR to CF HAE to restore mucus transport, thus correcting the CF phenotype. PIVCFTR delivered CFTR to >60% of airway surface epithelial cells and expressed CFTR protein in CF HAE approximately 100-fold over endogenous levels in non-CF HAE. This efficiency of CFTR delivery fully corrected the basic bioelectric defects of Cl(-) and Na(+) epithelial ion transport and restored ASL volume regulation and mucus transport to levels approaching those of non-CF HAE. To determine the numbers of CF HAE surface epithelial cells required to express CFTR for restoration of mucus transport to normal levels, different amounts of PIVCFTR were used to express CFTR in 3%-65% of the surface epithelial cells of CF HAE and correlated to increasing ASL volumes and mucus transport rates. These data demonstrate for the first time, to our knowledge, that restoration of normal mucus transport rates in CF HAE was achieved after CFTR delivery to 25% of surface epithelial cells. In vivo experimentation in appropriate models will be required to determine what level of mucus transport will afford clinical benefit to CF patients, but we predict that a future goal for corrective gene transfer to the CF human airways in vivo would attempt to target at least 25% of surface epithelial cells to achieve mucus transport rates comparable to those in non-CF airways.
Host responses to viral infection include both immune activation and programmed cell death. The mitochondrial antiviral signaling adaptor, MAVS (IPS-1, VISA or Cardif) is critical for host defenses ...to viral infection by inducing type-1 interferons (IFN-I), however its role in virus-induced apoptotic responses has not been elucidated.
We show that MAVS causes apoptosis independent of its function in initiating IFN-I production. MAVS-induced cell death requires mitochondrial localization, is caspase dependent, and displays hallmarks of apoptosis. Furthermore, MAVS(-/-) fibroblasts are resistant to Sendai virus-induced apoptosis. A functional screen identifies the hepatitis C virus NS3/4A and the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) nonstructural protein (NSP15) as inhibitors of MAVS-induced apoptosis, possibly as a method of immune evasion.
This study describes a novel role for MAVS in controlling viral infections through the induction of apoptosis, and identifies viral proteins which inhibit this host response.
The nucleotide-binding domain and leucine-rich-repeat-containing (NLR) proteins regulate innate immunity. Although the positive regulatory impact of NLRs is clear, their inhibitory roles are not well ...defined. We showed that
Nlrx1
−/−
mice exhibited increased expression of antiviral signaling molecules IFN-β, STAT2, OAS1, and IL-6 after influenza virus infection. Consistent with increased inflammation,
Nlrx1
−/−
mice exhibited marked morbidity and histopathology. Infection of these mice with an influenza strain that carries a mutated NS-1 protein, which normally prevents IFN induction by interaction with RNA and the intracellular RNA sensor RIG-I, further exacerbated IL-6 and type I IFN signaling. NLRX1 also weakened cytokine responses to the 2009 H1N1 pandemic influenza virus in human cells. Mechanistically,
Nlrx1 deletion led to constitutive interaction of MAVS and RIG-I. Additionally, an inhibitory function is identified for NLRX1 during LPS activation of macrophages where the MAVS-RIG-I pathway was not involved. NLRX1 interacts with TRAF6 and inhibits NF-κB activation. Thus, NLRX1 functions as a checkpoint of overzealous inflammation.
► NLRX1 attenuates IFN induction by preventing the interaction between RIG-I and MAVS ► NLRX1 functions as a negative regulator of IFN-I and IL-6 during influenza infection ► NLRX1 attenuates inflammation by intersecting the TRAF6 pathway to affect NF-κB
COVID-19, the disease caused by infection with SARS-CoV-2, requires urgent development of therapeutic interventions. Due to their safety, specificity, and potential for rapid advancement into the ...clinic, monoclonal antibodies (mAbs) represent a highly promising class of antiviral or anti-inflammatory agents. Herein, by analyzing prior efforts to advance antiviral mAbs for other acute respiratory infections (ARIs), we highlight the challenges faced by mAb-based immunotherapies for COVID-19. We present evidence supporting early intervention immediately following a positive diagnosis via inhaled delivery of mAbs with vibrating mesh nebulizers as a promising approach for the treatment of COVID-19.
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•Monoclonal antibodies (mAbs) represent a promising class of antiviral agents.•Systemically administered mAbs have previously failed to treat respiratory viruses.•Vibrating mesh nebulizers are routinely used in the home setting.•Treatment soon after diagnosis with nebulized mAbs may improve outcomes.
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