CoV Infection Research Articles

Rapid detection and monitoring of human coronavirus infections.

Human coronaviruses (CoVs) are increasingly recognized as important respiratory pathogens associated with a broad range of clinical diseases. We sought to increase the insight into clinically relevant CoV infections by monitoring antigen concentrations in six confirmed CoV-positive patients using a newly developed assay for rapid detection of CoV OC43 infections. Antigen positivity lasted 3 to 6 days in secondary infections and 13 days in primary infection. CoV infections are clinically diverse, are common, and cannot be diagnosed from clinical symptoms alone.

Intensive care admission for Coronavirus OC43 respiratory tract infections

BackgroundCoronavirus OC43 infection causes severe pneumonia in patients presenting with comorbidities, but clinical signs alone do not allow for viral identification. ObjectivesTo analyze acute manifestations of Coronavirus OC43 infections and outcomes of patients admitted to an intensive care unit (ICU). Patients and methodsRetrospective and monocentric study performed during a Coronavirus OC43 outbreak. We used multiplex PCR to detect an OC43 outbreak in Reunion Island during the 2016 Southern Hemisphere's winter: seven admissions to the ICU. ResultsMean age of patients was 71 [67;76] years, SAPS II was 42 [28;53], pneumonia severity index 159 [139;182] vs 73 [40.5;107] for patients in medical wards, and 43% required mechanical ventilation. Comorbidities were diabetes mellitus (87%), chronic respiratory failure (57%), and chronic renal failure (29%). One patient died from Haemophilus influenzae co-infection. ConclusionAs for MERS Co-V infections, underlying comorbidities impacted the clinical outcomes of OC43 infections.

Longitudinal study of age-specific pattern of coronavirus infection in Lyle\u2019s flying fox (Pteropus lylei) in Thailand

BackgroundBats are natural reservoirs for several highly pathogenic and novel viruses including coronaviruses (CoVs) (mainly Alphacoronavirus and Betacoronavirus). Lyle’s flying fox (Pteropus lylei)‘s roosts and foraging sites are usually in the proximity to humans and animals. Knowledge about age-specific pattern of CoV infection in P. lylei, prevalence, and viral shedding at roosts and foraging sites may have an impact on infection-age-structure model to control CoV outbreak.MethodsP. lylei bats were captured monthly during January–December 2012 for detection of CoV at three areas in Chonburi province; two human dwellings, S1 and S2, where few fruit trees were located with an open pig farm, 0.6 km and 5.5 km away from the bat roost, S3. Nested RT-PCR of RNA-dependent RNA polymerase (RdRp) gene from rectal swabs was used for CoV detection. The strain of CoV was confirmed by sequencing and phylogenetic analysis.ResultsCoV infection was found in both juveniles and adult bats between May and October (January, in adults only and April, in juveniles only). Of total rectal swab positives (68/367, 18.5%), ratio was higher in bats captured at S1 (11/44, 25.0%) and S2 (35/99, 35.4%) foraging sites than at roost (S3) (22/224, 9.8%). Juveniles (forearm length ≤ 136 mm) were found with more CoV infection than adults at all three sites; S1 (9/24, 37.5% vs 2/20, 10%), S2 (22/49, 44.9% vs 13/50, 26.0%), and S3 (10/30, 33.3% vs 12/194, 6.2%). The average BCI of CoV infected bats was significantly lower than uninfected bats. No gender difference related to infection was found at the sites. Phylogenetic analysis of conserved RdRp gene revealed that the detected CoVs belonged to group D betacoronavirus (n = 64) and alphacoronavirus (n = 4).ConclusionsThe fact that CoV infection and shedding was found in more juvenile than adult bats may suggest transmission from mother during peripartum period. Whether viral reactivation during parturition period or stress is responsible in maintaining transmission in the bat colony needs to be explored.

The calm before the storm: clinical observations of Middle East respiratory syndrome (MERS) patients

Background: Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection emerged in 2012. The majority of cases occurred in the Kingdom of Saudi Arabia and the disease carries a high case fatality rate.Methods: We present three MERS-CoV cases and highlight the salient clinical features and laboratory, and radiographic characteristics.Results: Although all nasopharyngeal samples were negative, MERS CoV infection was confirmed by reverse transcription–polymerase chain reaction of the E gene (UpE) and open reading frame (ORF1b) on sputum samples. The Ct value of the ORF1 gene was 24.8–29.11. One patient had been on immune suppressive agent and two patients had diabetes mellitus. The average length of hospital stay was 10.6 days. Two patients received ribavirin and IFN-a2b in addition to supportive management. The clinical course for these patients started with a febrile period lasting five days, a reduction in fever was coinciding with increased respiratory rate and oxygen requirements. All patients were discharged home. None of the 50 contacts tested positive for MERS-CoV.Conclusion:Resolution of the fever was accompanied by an increase in oxygen requirements and respiratory rate also lasting several days. This was followed by resolution of all symptoms and return to normal.

Murine Hepatitis Virus nsp14 Exoribonuclease Activity Is Required for Resistance to Innate Immunity

Coronaviruses (CoVs) are positive-sense RNA viruses that infect numerous mammalian and avian species and are capable of causing severe and lethal disease in humans. CoVs encode several innate immune antagonists that counteract the host innate immune response to facilitate efficient viral replication. CoV nonstructural protein 14 (nsp14) encodes 3'-to-5' exoribonuclease activity (ExoN), which performs a proofreading function and is required for high-fidelity replication. Outside of the order Nidovirales, arenaviruses are the only RNA viruses that encode an ExoN, which functions to degrade double-stranded RNA (dsRNA) replication intermediates. In this study, we tested the hypothesis that CoV ExoN also functions to antagonize the innate immune response. We demonstrate that viruses lacking ExoN activity [ExoN(-)] are sensitive to cellular pretreatment with interferon beta (IFN-β) in a dose-dependent manner. In addition, ExoN(-) virus replication was attenuated in wild-type bone marrow-derived macrophages (BMMs) and partially restored in interferon alpha/beta receptor-deficient (IFNAR-/-) BMMs. ExoN(-) virus replication did not result in IFN-β gene expression, and in the presence of an IFN-β-mediated antiviral state, ExoN(-) viral RNA levels were not substantially reduced relative to those of untreated samples. However, ExoN(-) virus generated from IFN-β-pretreated cells had reduced specific infectivity and decreased relative fitness, suggesting that ExoN(-) virus generated during an antiviral state is less viable to establish a subsequent infection. Overall, our data suggest murine hepatitis virus (MHV) ExoN activity is required for resistance to the innate immune response, and antiviral mechanisms affecting the viral RNA sequence and/or an RNA modification act on viruses lacking ExoN activity.IMPORTANCE CoVs encode multiple antagonists that prevent or disrupt an efficient innate immune response. Additionally, no specific antiviral therapies or vaccines currently exist for human CoV infections. Therefore, the study of CoV innate immune antagonists is essential for understanding how CoVs overcome host defenses and to maximize potential therapeutic interventions. Here, we sought to determine the contributions of nsp14 ExoN activity in the induction of and resistance to the innate immune response. We show that viruses lacking nsp14 ExoN activity are more sensitive than wild-type MHV to restriction by exogenous IFN-β and that viruses produced in the presence of an antiviral state are less capable of establishing a subsequent viral infection. Our results support the hypothesis that murine hepatitis virus ExoN activity is required for resistance to the innate immune response.

The tetraspanin CD9 facilitates MERS-coronavirus entry by scaffolding host cell receptors and proteases.

Infection by enveloped coronaviruses (CoVs) initiates with viral spike (S) proteins binding to cellular receptors, and is followed by proteolytic cleavage of receptor-bound S proteins, which prompts S protein-mediated virus-cell membrane fusion. Infection therefore requires close proximity of receptors and proteases. We considered whether tetraspanins, scaffolding proteins known to facilitate CoV infections, hold receptors and proteases together on cell membranes. Using knockout cell lines, we found that the tetraspanin CD9, but not the tetraspanin CD81, formed cell-surface complexes of dipeptidyl peptidase 4 (DPP4), the MERS-CoV receptor, and the type II transmembrane serine protease (TTSP) member TMPRSS2, a CoV-activating protease. This CD9-facilitated condensation of receptors and proteases allowed MERS-CoV pseudoviruses to enter cells rapidly and efficiently. Without CD9, MERS-CoV viruses were not activated by TTSPs, and they trafficked into endosomes to be cleaved much later and less efficiently by cathepsins. Thus, we identified DPP4:CD9:TTSP as the protein complexes necessary for early, efficient MERS-CoV entry. To evaluate the importance of these complexes in an in vivo CoV infection model, we used recombinant Adenovirus 5 (rAd5) vectors to express human DPP4 in mouse lungs, thereby sensitizing the animals to MERS-CoV infection. When the rAd5-hDPP4 vectors co-expressed small RNAs silencing Cd9 or Tmprss2, the animals were significantly less susceptible, indicating that CD9 and TMPRSS2 facilitated robust in vivo MERS-CoV infection of mouse lungs. Furthermore, the S proteins of virulent mouse-adapted MERS-CoVs acquired a CD9-dependent cell entry character, suggesting that CD9 is a selective agent in the evolution of CoV virulence.

In Situ Tagged nsp15 Reveals Interactions with Coronavirus Replication/Transcription Complex-Associated Proteins.

ABSTRACTCoronavirus (CoV) replication and transcription are carried out in close proximity to restructured endoplasmic reticulum (ER) membranes in replication/transcription complexes (RTC). Many of the CoV nonstructural proteins (nsps) are required for RTC function; however, not all of their functions are known. nsp15 contains an endoribonuclease domain that is conserved in the CoV family. While the enzymatic activity and crystal structure of nsp15 are well defined, its role in replication remains elusive. nsp15 localizes to sites of RNA replication, but whether it acts independently or requires additional interactions for its function remains unknown. To begin to address these questions, we created an in situ tagged form of nsp15 using the prototypic CoV, mouse hepatitis virus (MHV). In MHV, nsp15 contains the genomic RNA packaging signal (P/S), a 95-bp RNA stem-loop structure that is not required for viral replication or nsp15 function. Utilizing this knowledge, we constructed an internal hemagglutinin (HA) tag that replaced the P/S. We found that nsp15-HA was localized to discrete perinuclear puncta and strongly colocalized with nsp8 and nsp12, both well-defined members of the RTC, but not the membrane (M) protein, involved in virus assembly. Finally, we found that nsp15 interacted with RTC-associated proteins nsp8 and nsp12 during infection, and this interaction was RNA independent. From this, we conclude that nsp15 localizes and interacts with CoV proteins in the RTC, suggesting it plays a direct or indirect role in virus replication. Furthermore, the use of in situ epitope tags could be used to determine novel nsp-nsp interactions in coronaviruses.

Proteolytic processing of Middle East respiratory syndrome coronavirus spikes expands virus tropism

Middle East respiratory syndrome coronavirus (MERS-CoV) infects humans from zoonotic sources and causes severe pulmonary disease. Virions require spike (S) glycoproteins for binding to cell receptors and for catalyzing virus-cell membrane fusion. Fusion occurs only after S proteins are cleaved sequentially, first during their secretion through the exocytic organelles of virus-producing cells, and second after virus binding to target-cell receptors. To more precisely determine how sequential proteolysis contributes to CoV infection, we introduced S mutations obstructing the first cleavages. These mutations severely compromised MERS-CoV infection into human lung-derived cells, but had little effect on infection into several other cell types. These cell type-specific requirements for proteolysis correlated with S conformations during cell entry. Without the first cleavages, S proteins resisted cell receptor-induced conformational changes, which restricted the second, fusion-activating cleavages. Consistent with these findings, precleaved MERS viruses used receptor-proximal, cell-surface proteases to effect the second fusion-activating cleavages during cell entry, whereas the more rigid uncleaved MERS viruses trafficked past these cell-surface proteases and into endosomes. Uncleaved viruses were less infectious to human airway epithelial and Calu3 cell cultures because they lacked sufficient endosomal fusion-activating proteases. Thus, by sensitizing viruses to receptor-induced conformational changes, the first S cleavages expand virus tropism to cell types that are relevant to lung infection, and therefore may be significant determinants of MERS-CoV virulence.

Coronaviruses - drug discovery and therapeutic options.

In humans, infections with the human coronavirus (HCoV) strains HCoV-229E, HCoV-OC43, HCoV-NL63 and HCoV-HKU1 usually result in mild, self-limiting upper respiratory tract infections, such as the common cold. By contrast, the CoVs responsible for severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), which were discovered in Hong Kong, China, in 2003, and in Saudi Arabia in 2012, respectively, have received global attention over the past 12 years owing to their ability to cause community and health-care-associated outbreaks of severe infections in human populations. These two viruses pose major challenges to clinical management because there are no specific antiviral drugs available. In this Review, we summarize the epidemiology, virology, clinical features and current treatment strategies of SARS and MERS, and discuss the discovery and development of new virus-based and host-based therapeutic options for CoV infections.

Recent progress in the discovery of inhibitors targeting coronavirus proteases.

Coronaviruses (CoVs) can cause highly prevalent diseases in humans and animals. The fatal outbreak of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) highlights the threat posed by this unique virus subfamily. However, no specific drugs have been approved to treat CoV-associated diseases to date. The CoV proteases, which play pivotal roles in viral gene expression and replication through a highly complex cascade involving the proteolytic processing of replicase polyproteins, are attractive targets for drug design. This review summarizes the recent advances in biological and structural studies, together with the development of inhibitors targeting CoV proteases, particularly main proteases (Mpros), which could help develop effective treatments to prevent CoV infection.

Crystal Structure of Feline Infectious Peritonitis Virus Main Protease in Complex with Synergetic Dual Inhibitors.

Coronaviruses (CoVs) can cause highly prevalent diseases in humans and animals. Feline infectious peritonitis virus (FIPV) belongs to the genus Alphacoronavirus, resulting in a lethal systemic granulomatous disease called feline infectious peritonitis (FIP), which is one of the most important fatal infectious diseases of cats worldwide. No specific vaccines or drugs have been approved to treat FIP. CoV main proteases (M(pro)s) play a pivotal role in viral transcription and replication, making them an ideal target for drug development. Here, we report the crystal structure of FIPV M(pro) in complex with dual inhibitors, a zinc ion and a Michael acceptor. The complex structure elaborates a unique mechanism of two distinct inhibitors synergizing to inactivate the protease, providing a structural basis to design novel antivirals and suggesting the potential to take advantage of zinc as an adjunct therapy against CoV-associated diseases. Coronaviruses (CoVs) have the largest genome size among all RNA viruses. CoV infection causes various diseases in humans and animals, including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). No approved specific drugs or vaccinations are available to treat their infections. Here, we report a novel dual inhibition mechanism targeting CoV main protease (M(pro)) from feline infectious peritonitis virus (FIPV), which leads to lethal systemic granulomatous disease in cats. M(pro), conserved across all CoV genomes, is essential for viral replication and transcription. We demonstrated that zinc ion and a Michael acceptor-based peptidomimetic inhibitor synergistically inactivate FIPV M(pro). We also solved the structure of FIPV M(pro) complexed with two inhibitors, delineating the structural view of a dual inhibition mechanism. Our study provides new insight into the pharmaceutical strategy against CoV M(pro) through using zinc as an adjuvant therapy to enhance the efficacy of an irreversible peptidomimetic inhibitor.

Brain Invasion by Mouse Hepatitis Virus Depends on Impairment of Tight Junctions and Beta Interferon Production in Brain Microvascular Endothelial Cells.

Coronaviruses (CoVs) have shown neuroinvasive properties in humans and animals secondary to replication in peripheral organs, but the mechanism of neuroinvasion is unknown. The major aim of our work was to evaluate the ability of CoVs to enter the central nervous system (CNS) through the blood-brain barrier (BBB). Using the highly hepatotropic mouse hepatitis virus type 3 (MHV3), its attenuated variant, 51.6-MHV3, which shows low tropism for endothelial cells, and the weakly hepatotropic MHV-A59 strain from the murine coronavirus group, we investigated the virus-induced dysfunctions of BBB in vivo and in brain microvascular endothelial cells (BMECs) in vitro. We report here a MHV strain-specific ability to cross the BBB during acute infection according to their virulence for liver. Brain invasion was observed only in MHV3-infected mice and correlated with enhanced BBB permeability associated with decreased expression of zona occludens protein 1 (ZO-1), VE-cadherin, and occludin, but not claudin-5, in the brain or in cultured BMECs. BBB breakdown in MHV3 infection was not related to production of barrier-dysregulating inflammatory cytokines or chemokines by infected BMECs but rather to a downregulation of barrier protective beta interferon (IFN-β) production. Our findings highlight the importance of IFN-β production by infected BMECs in preserving BBB function and preventing access of blood-borne infectious viruses to the brain. Coronaviruses (CoVs) infect several mammals, including humans, and are associated with respiratory, gastrointestinal, and/or neurological diseases. There is some evidence that suggest that human respiratory CoVs may show neuroinvasive properties. Indeed, the severe acute respiratory syndrome coronavirus (SARS-CoV), causing severe acute respiratory syndrome, and the CoVs OC43 and 229E were found in the brains of SARS patients and multiple sclerosis patients, respectively. These findings suggest that hematogenously spread CoVs may gain access to the CNS at the BBB level. Herein we report for the first time that CoVs exhibit the ability to cross the BBB according to strain virulence. BBB invasion by CoVs correlates with virus-induced disruption of tight junctions on BMECs, leading to BBB dysfunction and enhanced permeability. We provide evidence that production of IFN-β by BMECs during CoV infection may prevent BBB breakdown and brain viral invasion.

A Coronavirus E Protein Is Present in Two Distinct Pools with Different Effects on Assembly and the Secretory Pathway.

Coronaviruses (CoVs) assemble by budding into the lumen of the early Golgi complex prior to exocytosis. The small CoV envelope (E) protein plays roles in assembly, virion release, and pathogenesis. CoV E has a single hydrophobic domain (HD), is targeted to Golgi complex membranes, and has cation channel activity in vitro. However, the precise functions of the CoV E protein during infection are still enigmatic. Structural data for the severe acute respiratory syndrome (SARS)-CoV E protein suggest that it assembles into a homopentamer. Specific residues in the HD regulate the ion-conducting pore formed by SARS-CoV E in artificial bilayers and the pathogenicity of the virus during infection. The E protein from the avian infectious bronchitis virus (IBV) has dramatic effects on the secretory system which require residues in the HD. Here, we use the known structural data from SARS-CoV E to infer the residues important for ion channel activity and the oligomerization of IBV E. We present biochemical data for the formation of two distinct oligomeric pools of IBV E in transfected and infected cells and the residues required for their formation. A high-order oligomer of IBV E is required for the production of virus-like particles (VLPs), implicating this form of the protein in virion assembly. Additionally, disruption of the secretory pathway by IBV E correlates with a form that is likely monomeric, suggesting that the effects on the secretory pathway are independent of E ion channel activity. CoVs are important human pathogens with significant zoonotic potential, as demonstrated by the emergence of SARS-CoV and Middle East respiratory syndrome (MERS)-CoV. Progress has been made toward identifying potential vaccine candidates in mouse models of CoV infection, including the use of attenuated viruses that lack the CoV E protein or express E-protein mutants. However, no approved vaccines or antiviral therapeutics exist. We previously reported that the hydrophobic domain of the IBV E protein, a putative viroporin, causes disruption of the mammalian secretory pathway when exogenously expressed in cells. Understanding the mechanism of this disruption could lead to the identification of novel antiviral therapeutics. Here, we present biochemical evidence for two distinct oligomeric forms of IBV E, one essential for assembly and the other with a role in disruption of the secretory pathway. Discovery of two forms of CoV E protein will provide additional targets for antiviral therapeutics.

Coronavirus and influenza virus proteolytic priming takes place in tetraspanin-enriched membrane microdomains.

Coronaviruses (CoVs) and low-pathogenicity influenza A viruses (LP IAVs) depend on target cell proteases to cleave their viral glycoproteins and prime them for virus-cell membrane fusion. Several proteases cluster into tetraspanin-enriched microdomains (TEMs), suggesting that TEMs are preferred virus entry portals. Here we found that several CoV receptors and virus-priming proteases were indeed present in TEMs. Isolated TEMs, when mixed with CoV and LP IAV pseudoparticles, cleaved viral fusion proteins to fusion-primed fragments and potentiated viral transductions. That entering viruses utilize TEMs as a protease source was further confirmed using tetraspanin antibodies and tetraspanin short hairpin RNAs (shRNAs). Tetraspanin antibodies inhibited CoV and LP IAV infections, but their virus-blocking activities were overcome by expressing excess TEM-associated proteases. Similarly, cells with reduced levels of the tetraspanin CD9 resisted CoV pseudoparticle transductions but were made susceptible by overproducing TEM-associated proteases. These findings indicated that antibodies and CD9 depletions interfere with viral proteolytic priming in ways that are overcome by surplus proteases. TEMs appear to be exploited by some CoVs and LP IAVs for appropriate coengagement with cell receptors and proteases. Enveloped viruses use their surface glycoproteins to catalyze membrane fusion, an essential cell entry step. Host cell components prime these viral surface glycoproteins to catalyze membrane fusion at specific times and places during virus cell entry. Among these priming components are proteases, which cleave viral surface glycoproteins, unleashing them to refold in ways that catalyze virus-cell membrane fusions. For some enveloped viruses, these proteases are known to reside on target cell surfaces. This research focuses on coronavirus and influenza A virus cell entry and identifies TEMs as sites of viral proteolysis, thereby defining subcellular locations of virus priming with greater precision. Implications of these findings extend to the use of virus entry antagonists, such as protease inhibitors, which might be most effective when localized to these microdomains.

MERS CoV Infection in Two Renal Transplant Recipients: Case Report

Middle East Respiratory Syndrome Coronavirus (MERS CoV) infection has recently emerged as a cause of severe potentially fatal pneumonia. The clinical presentation ranges from asymptomatic infection to severe pneumonia and acute renal failure. Data on the clinical presentation in solid organ transplant recipients are lacking. We report two cases of MERS CoV infections in two renal transplant recipients with variable clinical presentations and outcomes. The first patient presented with progressive respiratory symptoms, acute renal failure and died. While the second patient presented with respiratory tract symptoms, remained stable and had an excellent clinical recovery despite recent reception of thymoglobulin induction. This is a rare report of MERS CoV infection in renal transplant recipients. Further data are needed to gain better understanding of the impact of anti‐rejection immunosuppressive therapy on the clinical presentation, severity and outcome of MERS CoV infections in solid organ transplant recipients.

Middle East Respiratory Syndrome Coronavirus: Current Status and Future Implications

In September 2012, a novel coronavirus was recognized, later renamed Middle East Respiratory Syndrome Coronavirus. This novel coronavirus belong lineage C of the genus Beta coronavirus included virus isolates from bats and camels. Fever, cough and shortness of breath were the common initial symptoms. On the other hand, majority of Patients were rapidly progressed to severe pneumonia and renal failure. Dromedary camels are suspected the primary reservoir for MERS CoV infection; suggesting camels to human transmission via contact with their excretion and consuming their product. However, human to human transmission occurred via the respiratory droplet or close contact. There is no specific drug or vaccine available for illnesses caused by MERS-CoV infection. Currently this novel virus is the major emerging respiratory pathogen threats of the world and capable of lethal human infections. Still new cases have been reported around the world particularly Arabian Peninsula. It has been also emerged outside Middle East countries which have not occurred before in South Korea and China since 20 May, 2015.

Coronavirus nonstructural protein 1: Common and distinct functions in the regulation of host and viral gene expression

The recent emergence of two highly pathogenic human coronaviruses (CoVs), severe acute respiratory syndrome CoV and Middle East respiratory syndrome CoV, has ignited a strong interest in the identification of viral factors that determine the virulence and pathogenesis of CoVs. The nonstructural protein 1 (nsp1) of CoVs has attracted considerable attention in this regard as a potential virulence factor and a target for CoV vaccine development because of accumulating evidence that point to its role in the downregulation of host innate immune responses to CoV infection. Studies have revealed both functional conservation and mechanistic divergence among the nsp1 of different mammalian CoVs in perturbing host gene expression and antiviral responses. This review summarizes the current knowledge about the biological functions of CoV nsp1 that provides an insight into the novel strategies utilized by this viral protein to modulate host and viral gene expression during CoV infection.

Middle Eastern Respiratory Syndrome Corona Virus (MERS CoV): case reports from a tertiary care hospital in Saudi Arabia.

BACKGROUND AND OBJECTIVESMiddle Eastern respiratory syndrome caused by novel coronavirus (MERS CoV) has been a major public health challenge since it was first described in 2012 in Saudi Arabia. So far, there is no effective treatment for this serious illness, which features a high mortality rate. We report an initial experience of the use of ribavirin and interferon (IFN)-α2b in the management of MERS CoV at a tertiary care hospital.DESIGN AND SETTINGSA case series of 6 patients admitted with a confirmed diagnosis of MERS CoV were treated with ribavirin and IFN-α2b in addition to supportive management. The patients’ demographics, clinical parameters, and outcomes were recorded. Fifty-four close contacts of these patients were screened for MERS CoV.METHODSSix patients with MERS CoV infection were included in this study. Four cases featured symptomatic disease, including pneumonia and respiratory failure, while 2 were asymptomatic close contacts of the MERS CoV patients. The MERS CoV infection was confirmed by reverse transcription–polymerase chain reaction detection of the consensus viral RNA targets upstream of the E gene (UPE) and open reading frame (ORF1b) on a sputum sample. The patients’ demographics, comorbid conditions, time to diagnosis and initiation of treatment, and clinical outcomes were recorded.RESULTSThree out of 6 patients who had comorbid conditions died during the study period, while 3 had successful outcomes. The diagnosis and treatment was delayed by an average of 15 days in those patients who died. Only 2 close contacts out of the 54 screened (3.7%) were positive for MERS CoV.CONCLUSIONTreatment with ribavirin and IFN-α2b may be effective in patients infected with MERS CoV. There appears to be a low infectivity rate among close contacts of MERS CoV patients.

Sensitivity of SARS/MERS CoV to interferons and other drugs based on achievable serum concentrations in humans.

A novel coronavirus (MERS-CoV) related to SARS-CoV recently emerged in the Middle East causing more than 400 deaths with a mortality rate of about 30%, much higher than SARS-CoV. Both viruses target epithelial cells in the respiratory tract, although utilizing different cellular receptors. Because of the sporadic nature of the MERS outbreak and difficulty in collecting randomized, controlled clinical data, the objective of this review was to focus on published in vitro and in vivo drug sensitivity data using both cell lines and available animal models of SARS/MERS CoV infection. Determination of drug activity was based on achievable serum levels in humans relative to in vitro IC50 (50% inhibitory concentration) or EC50 (50% effective concentration) drug concentrations. The most active drugs against SARS/MERS CoV at clinically achievable serum levels were type I interferons and a TLR3 agonist, interferon inducer/activator.

Coronaviruses induce entry-independent, continuous macropinocytosis.

ABSTRACTMacropinocytosis is exploited by many pathogens for entry into cells. Coronaviruses (CoVs) such as severe acute respiratory syndrome (SARS) CoV and Middle East respiratory syndrome CoV are important human pathogens; however, macropinocytosis during CoV infection has not been investigated. We demonstrate that the CoVs SARS CoV and murine hepatitis virus (MHV) induce macropinocytosis, which occurs late during infection, is continuous, and is not associated with virus entry. MHV-induced macropinocytosis results in vesicle internalization, as well as extended filopodia capable of fusing with distant cells. MHV-induced macropinocytosis requires fusogenic spike protein on the cell surface and is dependent on epidermal growth factor receptor activation. Inhibition of macropinocytosis reduces supernatant viral titers and syncytia but not intracellular virus titers. These results indicate that macropinocytosis likely facilitates CoV infection through enhanced cell-to-cell spreading. Our studies are the first to demonstrate virus use of macropinocytosis for a role other than entry and suggest a much broader potential exploitation of macropinocytosis in virus replication and host interactions.