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Viruses exploit the host lipid metabolism machinery to achieve efficient replication. We herein characterize the lipids profile reprogramming

Graphical abstract, Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne virus that causes severe infection in humans characterized by an acute febrile illness with thrombocytopenia and hemorrhagic complications, and a mortality rate of up to 30%. Understanding on virus-host protein interactions may facilitate the identification of druggable antiviral targets. Herein, we utilized liquid chromatography-tandem mass spectrometry to characterize the SFTSV interactome in human embryonic kidney-derived permanent culture (HEK-293T) cells. We identified 445 host proteins that co-precipitated with the viral glycoprotein N, glycoprotein C, nucleoprotein, or nonstructural protein. A network of SFTSV-host protein interactions based on reduced viral fitness affected upon host factor down-regulation was then generated. Screening of the DrugBank database revealed numerous drug compounds that inhibited the prioritized host factors in this SFTSV interactome. Among these drug compounds, the clinically approved artenimol (an antimalarial) and omacetaxine mepesuccinate (a cephalotaxine) were found to exhibit anti-SFTSV activity in vitro. The higher selectivity of artenimol (71.83) than omacetaxine mepesuccinate (8.00) highlights artenimol’s potential for further antiviral development. Mechanistic evaluation showed that artenimol interfered with the interaction between the SFTSV nucleoprotein and the host glucose-6-phosphate isomerase (GPI), and that omacetaxine mepesuccinate interfered with the interaction between the viral nucleoprotein with the host ribosomal protein L3 (RPL3). In summary, the novel interactomic data in this study revealed the virus-host protein interactions in SFTSV infection and facilitated the discovery of potential anti-SFTSV treatments.

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus that poses significant threats to global public health. Macrophages and dendritic cells are both key sentinel cells in the host immune response and play critical roles in the pathogenesis of flavivirus infections. Recent studies showed that ZIKV could productively infect monocyte-derived dendritic cells (moDCs), but the role of macrophages in ZIKV infection remains incompletely understood. In this study, we first compared ZIKV infection in monocyte-derived macrophages (MDMs) and moDCs derived from the same donors. We demonstrated that while both MDMs and moDCs were susceptible to epidemic (Puerto Rico) and pre-epidemic (Uganda) strains of ZIKV, virus replication was largely restricted in MDMs but not in moDCs. ZIKV induced significant apoptosis in moDCs but not MDMs. The restricted virus replication in MDMs was not due to inefficient virus entry but was related to post-entry events in the viral replication cycle. In stark contrast with moDCs, ZIKV failed to inhibit STAT1 and STAT2 phosphorylation in MDMs. This resulted in the lack of efficient antagonism of the host type I interferon-mediated antiviral responses. Importantly, depletion of STAT2 but not STAT1 in MDMs significantly rescued the replication of ZIKV and the prototype flavivirus yellow fever virus. Overall, our findings revealed a differential interplay between macrophages and dendritic cells with ZIKV. While dendritic cells may be exploited by ZIKV to facilitate virus replication, macrophages restricted ZIKV infection.

The in vivo pathogenicity, transmissibility, and fitness of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron (B.1.1.529) variant are not well understood. We compared these virological attributes of this new variant of concern (VOC) with those of the Delta (B.1.617.2) variant in a Syrian hamster model of COVID-19. Omicron-infected hamsters lost significantly less body weight and exhibited reduced clinical scores, respiratory tract viral burdens, cytokine and chemokine dysregulation, and lung damage than Delta-infected hamsters. Both variants were highly transmissible through contact transmission. In noncontact transmission studies Omicron demonstrated similar or higher transmissibility than Delta. Delta outcompeted Omicron without selection pressure, but this scenario changed once immune selection pressure with neutralizing antibodies—active against Delta but poorly active against Omicron—was introduced. Next-generation vaccines and antivirals effective against this new VOC are therefore urgently needed.

The Coronavirus Disease 2019 (COVID-19) pandemic caused by the novel lineage B betacoroanvirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in significant mortality, morbidity, and socioeconomic disruptions worldwide. Effective antivirals are urgently needed for COVID-19. The main protease (Mpro) of SARS-CoV-2 is an attractive antiviral target because of its essential role in the cleavage of the viral polypeptide. In this study, we performed an in silico structure-based screening of a large chemical library to identify potential SARS-CoV-2 Mpro inhibitors. Among 8,820 compounds in the library, our screening identified trichostatin A, a histone deacetylase inhibitor and an antifungal compound, as an inhibitor of SARS-CoV-2 Mpro activity and replication. The half maximal effective concentration of trichostatin A against SARS-CoV-2 replication was 1.5 to 2.7µM, which was markedly below its 50% effective cytotoxic concentration (75.7µM) and peak serum concentration (132µM). Further drug compound optimization to develop more stable analogues with longer half-lives should be performed. This structure-based drug discovery platform should facilitate the identification of additional enzyme inhibitors of SARS-CoV-2.

The Coronavirus Disease 2019 (COVID-19) pandemic is unlikely to abate until sufficient herd immunity is built up by either natural infection or vaccination. We previously identified ten linear immunodominant sites on the SARS-CoV-2 spike protein of which four are located within the RBD. Therefore, we designed two linkerimmunodominant site (LIS) vaccine candidates which are composed of four immunodominant sites within the RBD (RBD-ID) or all the 10 immunodominant sites within the whole spike (S-ID). They were administered by subcutaneous injection and were tested for immunogenicity and in vivo protective efficacy in a hamster model for COVID-19. We showed that the S-ID vaccine induced significantly better neutralizing antibody response than RBD-ID and alum control. As expected, hamsters vaccinated by S-ID had significantly less body weight loss, lung viral load, and histopathological changes of pneumonia. The S-ID has the potential to be an effective vaccine for protection against COVID-19.

"Pan-coronavirus" antivirals targeting conserved viral components can be designed. Here, we show that the rationally engineered H84T-banana lectin (H84T-BanLec), which specifically recognizes high mannose found on viral proteins but seldom on healthy human cells, potently inhibits Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (including Omicron), and other human-pathogenic coronaviruses at nanomolar concentrations. H84T-BanLec protects against MERS-CoV and SARS-CoV-2 infection in vivo. Importantly, intranasally and intraperitoneally administered H84T-BanLec are comparably effective. Mechanistic assays show that H84T-BanLec targets virus entry. High-speed atomic force microscopy depicts real-time multimolecular associations of H84T-BanLec dimers with the SARS-CoV-2 spike trimer. Single-molecule force spectroscopy demonstrates binding of H84T-BanLec to multiple SARS-CoV-2 spike mannose sites with high affinity and that H84T-BanLec competes with SARS-CoV-2 spike for binding to cellular ACE2. Modeling experiments identify distinct high-mannose glycans in spike recognized by H84T-BanLec. The multiple H84T-BanLec binding sites on spike likely account for the drug compound's broad-spectrum antiviral activity and the lack of resistant mutants.

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect human and other mammals, including hamsters. Syrian (Mesocricetus auratus) and dwarf (Phodopus sp.) hamsters are susceptible to SARS-CoV-2 infection in the laboratory setting. However, pet shop-related Coronavirus Disease 2019 (COVID-19) outbreaks have not been reported. Methods We conducted an investigation of a pet shop-related COVID-19 outbreak due to Delta variant AY.127 involving at least 3 patients in Hong Kong. We tested samples collected from the patients, environment, and hamsters linked to this outbreak and performed whole genome sequencing analysis of the reverse transcription polymerase chain reaction (RT-PCR)-positive samples. Results The patients included a pet shop keeper (Patient 1), a female customer of the pet shop (Patient 2), and the husband of Patient 2 (Patient 3). Investigation showed that 17.2% (5/29) and 25.5% (13/51) environmental specimens collected from the pet shop and its related warehouse, respectively, tested positive for SARS-CoV-2 RNA by RT-PCR. Among euthanized hamsters randomly collected from the storehouse, 3% (3/100) tested positive for SARS-CoV-2 RNA by RT-PCR and seropositive for anti-SARS-CoV-2 antibody by enzyme immunoassay. Whole genome analysis showed that although all genomes from the outbreak belonged to the Delta variant AY.127, there were at least 3 nucleotide differences among the genomes from different patients and the hamster cages. Genomic analysis suggests that multiple strains have emerged within the hamster population, and these different strains have likely transmitted to human either via direct contact or via the environment. Conclusions Our study demonstrated probable hamster-to-human transmission of SARS-CoV-2. As pet trading is common around the world, this can represent a route of international spread of this pandemic virus.

Extrapulmonary complications of different organ systems have been increasingly recognized in patients with severe or chronic Coronavirus Disease 2019 (COVID-19). However, limited information on the skeletal complications of COVID-19 is known, even though inflammatory diseases of the respiratory tract have been known to perturb bone metabolism and cause pathological bone loss. In this study, we characterized the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on bone metabolism in an established golden Syrian hamster model for COVID-19. SARS-CoV-2 causes significant multifocal loss of bone trabeculae in the long bones and lumbar vertebrae of all infected hamsters. The bone loss progressively worsens from the acute phase to the post-recovery phase. Mechanistically, the bone loss was associated with SARS-CoV-2-induced cytokine dysregulation which upregulates osteoclastic differentiation of monocyte-macrophage lineage. The pro-inflammatory cytokines further trigger a second wave of cytokine storm in the skeletal tissues to augment their pro-osteoclastogenesis effect. Our findings in this established hamster model suggest that pathological bone loss may be a neglected complication which warrants more extensive investigations during the long-term follow-up of COVID-19 patients. The benefits of potential prophylactic and therapeutic interventions against pathological bone loss should be further evaluated. O_FIG O_LINKSMALLFIG WIDTH=188 HEIGHT=200 SRC="FIGDIR/small/463665v1_ufig1.gif" ALT="Figure 1"> View larger version (81K): org.highwire.dtl.DTLVardef@ada9b8org.highwire.dtl.DTLVardef@1617fcaorg.highwire.dtl.DTLVardef@cdcd3org.highwire.dtl.DTLVardef@75a0ab_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstractSARS-CoV-2 infection causes pathological bone loss in golden Syrian hamsters through induction of cytokine storm and inflammation-induced osteoclastogenesis.

Robust severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in nasal turbinate (NT) accounts for high viral transmissibility, yet whether neutralizing IgA antibodies can control it remains unknown. Here, we evaluated receptor binding domain (RBD)-specific monomeric B8-mIgA1 and B8-mIgA2, and dimeric B8-dIgA1 and B8-dIgA2 against intranasal SARS-CoV-2 challenge in Syrian hamsters. These antibodies exhibited comparably potent neutralization against authentic virus by competing with human angiotensin converting enzyme-2 (ACE2) receptor for RBD binding. While reducing viruses in lungs, pre-exposure intranasal B8-dIgA1 or B8-dIgA2 led to 81-fold more infectious viruses and severer damage in NT than placebo. Virus-bound B8-dIgA1 and B8-dIgA2 could engage CD209 as an alternative receptor for entry into ACE2-negative cells and allowed viral cell-to-cell transmission. Cryo-EM revealed B8 as a class II neutralizing antibody binding trimeric RBDs in 3-up or 2-up/1-down conformation. Therefore, RBD-specific neutralizing dIgA engages an unexpected action for enhanced SARS-CoV-2 nasal infection and injury in Syrian hamsters.

Robust severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in nasal turbinate (NT) accounts for high viral transmissibility, yet whether neutralizing IgA antibodies can control it remains unknown. Here, we evaluated receptor binding domain (RBD)-specific monomeric B8-mIgA1 and B8-mIgA2, and dimeric B8-dIgA1 and B8-dIgA2 against intranasal SARS-CoV-2 challenge in Syrian hamsters. These antibodies exhibited comparably potent neutralization against authentic virus by competing with human angiotensin converting enzyme-2 (ACE2) receptor for RBD binding. While reducing viruses in lungs, pre-exposure intranasal B8-dIgA1 or B8-dIgA2 led to 81-fold more infectious viruses and severer damage in NT than placebo. Virus-bound B8-dIgA1 and B8-dIgA2 could engage CD209 as an alternative receptor for entry into ACE2-negative cells and allowed viral cell-to-cell transmission. Cryo-EM revealed B8 as a class II neutralizing antibody binding trimeric RBDs in 3-up or 2-up/1-down conformation. Therefore, RBD-specific neutralizing dIgA engages an unexpected action for enhanced SARS-CoV-2 nasal infection and injury in Syrian hamsters.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus in Asia that causes severe disease. Despite its clinical importance, treatment options for SFTSV infection remains limited. The SFTSV glycoprotein Gn plays a major role in mediating virus entry into host cells and is therefore a potential antiviral target. In this study, we employed an in silico structure-based strategy to design novel cyclic antiviral peptides that target the SFTSV glycoprotein Gn. Among the cyclic peptides, HKU-P1 potently neutralizes the SFTSV virion. Combinatorial treatment with HKU-P1 and the broad-spectrum viral RNA-dependent RNA polymerase inhibitor favipiravir exhibited synergistic antiviral effects in vitro. The in silico peptide design platform in this study may facilitate the generation of novel antiviral peptides for other emerging viruses.

Background The effect of low environmental temperature on viral shedding and disease severity of Coronavirus Disease 2019 (COVID-19) is uncertain. Methods We investigated the virological, clinical, pathological, and immunological changes in hamsters housed at room (21°C), low (12–15°C), and high (30–33°C) temperature after challenge by 105 plaque-forming units of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Results The nasal turbinate, trachea, and lung viral load and live virus titer were significantly higher (~0.5-log10 gene copies/β-actin, P Conclusions This study provided in vivo evidence that low environmental temperature exacerbated the degree of virus shedding, disease severity, and tissue proinflammatory cytokines/chemokines expression, and suppressed the neutralizing antibody response of SARS-CoV-2-infected hamsters. Keeping warm in winter may reduce the severity of COVID-19.

Coronaviruses have repeatedly crossed species barriers to cause epidemics1. “Pan-coronavirus” antivirals targeting conserved viral components involved in coronavirus replication, such as the extensively glycosylated spike protein, can be designed. Here we show that the rationally engineered H84T-banana lectin (H84T-BanLec), which specifically recognizes high-mannose found on viral proteins but seldom on healthy human cells2, potently inhibits the highly virulent MERS-CoV, pandemic SARS-CoV-2 and its variants, and other human-pathogenic coronaviruses at nanomolar concentrations. MERS-CoV-infected human DPP4-transgenic mice treated by H84T-BanLec have significantly higher survival, lower viral burden, and reduced pulmonary damage. Similarly, prophylactic or therapeutic H84T-BanLec is effective against SARS-CoV-2 in hamsters. Importantly, intranasally and intraperitoneally administered H84T-BanLec are comparably effective. Time-of-drug-addition assay shows that H84T-BanLec targets virus entry. Real-time structural analysis with high-speed atomic force microscopy depicts multi-molecular associations of H84T-BanLec dimers with the SARS-CoV-2 spike trimer. Single-molecule force spectroscopy demonstrates binding of H84T-BanLec to multiple SARS-CoV-2 spike mannose sites with high affinity, and that H84T-BanLec competes with SARS-CoV-2 spike for binding to cellular ACE2. Modelling experiments identify distinct high-mannose glycans in spike recognized by H84T-BanLec. The multiple H84T-BanLec binding sites on spike likely account for the activity against SARS-CoV-2 variants and the lack of resistant mutants. The broad-spectrum H84T-BanLec should be clinically evaluated in respiratory viral infections including COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is characterized by a burst in the upper respiratory portal for high transmissibility. To determine human neutralizing antibodies (HuNAbs) for entry protection, we tested three potent HuNAbs (IC50 range, 0.0007–0.35 μg/mL) against live SARS-CoV-2 infection in the golden Syrian hamster model. These HuNAbs inhibit SARS-CoV-2 infection by competing with human angiotensin converting enzyme-2 for binding to the viral receptor binding domain (RBD). Prophylactic intraperitoneal or intranasal injection of individual HuNAb or DNA vaccination significantly reduces infection in the lungs but not in the nasal turbinates of hamsters intranasally challenged with SARS-CoV-2. Although postchallenge HuNAb therapy suppresses viral loads and lung damage, robust infection is observed in nasal turbinates treated within 1–3 days. Our findings demonstrate that systemic HuNAb suppresses SARS-CoV-2 replication and injury in lungs; however, robust viral infection in nasal turbinate may outcompete the antibody with significant implications to subprotection, reinfection, and vaccine., Graphical Abstract, SARS-CoV-2 infection in nasal turbinate determines viral transmissibility. Zhou and colleagues interrogate site-specific prevention of SARS-CoV-2 in hamsters. Prophylactic intraperitoneal or intranasal HuNAb or intramuscular DNA vaccination prevents infection effectively in lungs but not in nasal turbinate. Rapid postchallenge HuNAb suppresses infection significantly in lungs but poorly in nasal turbinate.

SARS-CoV-2 is causing a pandemic of COVID-19, with high infectivity and significant mortality1. Currently, therapeutic options for COVID-19 are limited. Historically, metal compounds have found use as antimicrobial agents, but their antiviral activities have rarely been explored. Here, we test a set of metallodrugs and related compounds, and identify ranitidine bismuth citrate, a commonly used drug for the treatment of Helicobacter pylori infection, as a potent anti-SARS-CoV-2 agent, both in vitro and in vivo. Ranitidine bismuth citrate exhibited low cytotoxicity and protected SARS-CoV-2-infected cells with a high selectivity index of 975. Importantly, ranitidine bismuth citrate suppressed SARS-CoV-2 replication, leading to decreased viral loads in both upper and lower respiratory tracts, and relieved virus-associated pneumonia in a golden Syrian hamster model. In vitro studies showed that ranitidine bismuth citrate and its related compounds exhibited inhibition towards both the ATPase (IC50 = 0.69 µM) and DNA-unwinding (IC50 = 0.70 µM) activities of the SARS-CoV-2 helicase via an irreversible displacement of zinc(II) ions from the enzyme by bismuth(III) ions. Our findings highlight viral helicase as a druggable target and the clinical potential of bismuth(III) drugs or other metallodrugs for the treatment of SARS-CoV-2 infection.

Enterovirus A71 (EV-A71) is a common cause of hand, foot, and mouth disease. Severe EV-A71 infections may be associated with life-threatening neurological complications. However, the pathogenic mechanisms underlying these severe clinical and pathological features remain incompletely understood. Metabolites are known to play critical roles in multiple stages of the replication cycles of viruses. The metabolic reprogramming induced by viral infections is essential for optimal virus replication and may be potential antiviral targets. In this study, we applied targeted metabolomics profiling to investigate the metabolic changes of induced pluripotent human stem cell (iPSC)-derived neural progenitor cells (NPCs) upon EV-A71 infection. A targeted quantitation of polar metabolites identified 14 candidates with altered expression profiles. A pathway enrichment analysis pinpointed glucose metabolic pathways as being highly perturbed upon EV-A71 infection. Gene silencing of one of the key enzymes of glycolysis, 6-phosphofructo-2-kinase (PFKFB3), significantly suppressed EV-A71 replication in vitro. Collectively, we demonstrated the feasibility to manipulate EV-A71-triggered host metabolic reprogramming as a potential anti-EV-A71 strategy.

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) signals an urgent need for an expansion in treatment options. In this study, we investigated the anti-SARS-CoV-2 activities of 22 antiviral agents with known broad-spectrum antiviral activities against coronaviruses and/or other viruses. They were first evaluated in our primary screening in VeroE6 cells and then the most potent anti-SARS-CoV-2 antiviral agents were further evaluated using viral antigen expression, viral load reduction, and plaque reduction assays. In addition to remdesivir, lopinavir, and chloroquine, our primary screening additionally identified types I and II recombinant interferons, 25-hydroxycholesterol, and AM580 as the most potent anti-SARS-CoV-2 agents among the 22 antiviral agents. Betaferon (interferon-&beta, 1b) exhibited the most potent anti-SARS-CoV-2 activity in viral antigen expression, viral load reduction, and plaque reduction assays among the recombinant interferons. The lipogenesis modulators 25-hydroxycholesterol and AM580 exhibited EC50 at low micromolar levels and selectivity indices of &gt, 10.0. Combinational use of these host-based antiviral agents with virus-based antivirals to target different processes of the SARS-CoV-2 replication cycle should be evaluated in animal models and/or clinical trials.

Summary: Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported from China in January, 2020. SARS-CoV-2 is efficiently transmitted from person to person and, in 2 months, has caused more than 82 000 laboratory-confirmed cases of coronavirus disease 2019 (COVID-19) and 2800 deaths in 46 countries. The total number of cases and deaths has surpassed that of the 2003 severe acute respiratory syndrome coronavirus (SARS-CoV). Although both COVID-19 and severe acute respiratory syndrome (SARS) manifest as pneumonia, COVID-19 is associated with apparently more efficient transmission, fewer cases of diarrhoea, increased mental confusion, and a lower crude fatality rate. However, the underlying virus–host interactive characteristics conferring these observations on transmissibility and clinical manifestations of COVID-19 remain unknown. Methods: We systematically investigated the cellular susceptibility, species tropism, replication kinetics, and cell damage of SARS-CoV-2 and compared findings with those for SARS-CoV. We compared SARS-CoV-2 and SARS-CoV replication in different cell lines with one-way ANOVA. For the area under the curve comparison between SARS-CoV-2 and SARS-CoV replication in Calu3 (pulmonary) and Caco2 (intestinal) cells, we used Student's t test. We analysed cell damage induced by SARS-CoV-2 and SARS-CoV with one-way ANOVA. Findings: SARS-CoV-2 infected and replicated to comparable levels in human Caco2 cells and Calu3 cells over a period of 120 h (p=0·52). By contrast, SARS-CoV infected and replicated more efficiently in Caco2 cells than in Calu3 cells under the same multiplicity of infection (p=0·0098). SARS-CoV-2, but not SARS-CoV, replicated modestly in U251 (neuronal) cells (p=0·036). For animal species cell tropism, both SARS-CoV and SARS-CoV-2 replicated in non-human primate, cat, rabbit, and pig cells. SARS-CoV, but not SARS-CoV-2, infected and replicated in Rhinolophus sinicus bat kidney cells. SARS-CoV-2 consistently induced significantly delayed and milder levels of cell damage than did SARS-CoV in non-human primate cells (VeroE6, p=0·016; FRhK4, p=0·0004). Interpretation: As far as we know, our study presents the first quantitative data for tropism, replication kinetics, and cell damage of SARS-CoV-2. These data provide novel insights into the lower incidence of diarrhoea, decreased disease severity, and reduced mortality in patients with COVID-19, with respect to the pathogenesis and high transmissibility of SARS-CoV-2 compared with SARS-CoV. Funding: May Tam Mak Mei Yin, The Shaw Foundation Hong Kong, Richard Yu and Carol Yu, Michael Seak-Kan Tong, Respiratory Viral Research Foundation, Hui Ming, Hui Hoy and Chow Sin Lan Charity Fund, Chan Yin Chuen Memorial Charitable Foundation, Marina Man-Wai Lee, The Hong Kong Hainan Commercial Association South China Microbiology Research Fund, The Jessie & George Ho Charitable Foundation, Perfect Shape Medical, The Consultancy Service for Enhancing Laboratory Surveillance of Emerging Infectious Diseases and Research Capability on Antimicrobial Resistance for the Department of Health of the Hong Kong Special Administrative Region Government, The Theme-Based Research Scheme of the Research Grants Council, Sanming Project of Medicine in Shenzhen, and The High Level-Hospital Program, Health Commission of Guangdong Province, China.

SARS-CoV-2 is characterized by a burst in upper-respiratory portal for high transmissibility. To determine human neutralizing antibodies (HuNAbs) for entry protection, we generated HuNAbs that bind to conformational determinants of viral receptor binding domain (RBD). HuNAb ZDY20 prevented pseudovirus and live virus entry with IC 90 values of 1.24 µg/ml and 1 µg/ml, respectively, by competing with human cellular receptor ACE2 for RBD binding. Prophylactic intraperitoneal injection of 10 mg/ml ZDY20 significantly reduced infection in lungs but not nasal turbinate of hamsters intranasally-challenged with SARS-CoV-2. Although post-challenge ZDY20 therapy suppressed viral loads and lung damage, robust infection was found in nasal turbinate treated within 1-3 days. Our findings demonstrated that systemic HuNAb suppresses SARS-CoV-2 replication and lung injury, yet insufficient entry blockade may implicate vaccine sub-protection and re-infection. Funding: This study was partly supported by University Development Fund and Li Ka Shing Faculty of Medicine Matching Fund from HKU to AIDS Institute, Health@InnoHK (Centre for Virology, Vaccinology and Therapeutics), Innovation and Technology Commission, HKSAR of China; and donations of Lo Ying Shek Chi Wai Foundation, Richard Yu and Carol Yu, the Shaw Foundation of Hong Kong, Michael Seak-Kan Tong, May Tam Mak Mei Yin, Hui Ming, Hui Hoy and Chow Sin Lan Charity Fund Limited, Chan Yin Chuen Memorial Charitable Foundation, Marina Man-Wai Lee, the Hong Kong Hainan Commercial Association South China Microbiology Research Fund, the Jessie & George Ho Charitable Foundation, Perfect Shape Medical Limited, Kai Chong Tong, Foo Oi Foundation Limited, and Tse Kam Ming Laurence. ZC’s team was also partly supported by Theme-Based Research Scheme (T11706/18-N to ZC). Conflict of Interest: The authors declare no competing interests except that some authors are co-inventers of the presented HuNAbs in a patent application. Ethical Approval: This study was approved by the Institutional Review Board of University of Hong Kong/Hospital Authority Hong Kong West Cluster, Hong Kong East Cluster Research Ethics Committee, and Kowloon West Cluster Research Ethics Committee (UW 13-265, HKECREC-2018-068, KW/EX-20-038[144-26]).

Zika virus (ZIKV) infection may be associated with severe complications in fetuses and adults, but treatment options are limited. We performed an in silico structure-based screening of a large chemical library to identify potential ZIKV NS2B-NS3 protease inhibitors. Clinically approved drugs belonging to different drug classes were selected among the 100 primary hit compounds with the highest predicted binding affinities to ZIKV NS2B-NS3-protease for validation studies. ZIKV NS2B-NS3 protease inhibitory activity was validated in most of the selected drugs and in vitro anti-ZIKV activity was identified in two of them (novobiocin and lopinavir-ritonavir). Molecular docking and molecular dynamics simulations predicted that novobiocin bound to ZIKV NS2B-NS3-protease with high stability. Dexamethasone-immunosuppressed mice with disseminated ZIKV infection and novobiocin treatment had significantly (P

Zika virus (ZIKV) infection is associated with congenital malformations in infected fetuses and severe neurological and other systemic complications in adults. There are currently limited anti-ZIKV treatment options that are readily available and safe for use in pregnancy. In this drug repurposing study, bromocriptine was found to have inhibitory effects on ZIKV replication in cytopathic effect inhibition, virus yield reduction, and plaque reduction assays. Time-of-drug-addition assay showed that bromocriptine exerted anti-ZIKV activity between 0 and 12 h post-ZIKV inoculation, corroborating with post-entry events in the virus replication cycle prior to budding. Our docking model showed that bromocriptine interacted with several active site residues of the proteolytic cavity involving H51 and S135 in the ZIKV-NS2B-NS3 protease protein, and might occupy the active site and inhibit the protease activity of the ZIKV-NS2B-NS3 protein. A fluorescence-based protease inhibition assay confirmed that bromocriptine inhibited ZIKV protease activity. Moreover, bromocriptine exhibited synergistic effect with interferon-α2b against ZIKV replication in cytopathic effect inhibition assay. The availability of per vagina administration of bromocriptine as suppositories or vaginoadhesive discs and the synergistic anti-ZIKV activity between bromocriptine and type I interferon may make bromocriptine a potentially useful and readily available treatment option for ZIKV infection. The anti-ZIKV effects of bromocriptine should be evaluated in a suitable animal model.

Background Disseminated or fatal Zika virus (ZIKV) infections were reported in immunosuppressed patients. Existing interferon-signaling/receptor-deficient mouse models may not be suitable for evaluating treatment effects of recombinant interferons. Methods We developed a novel mouse model for ZIKV infection by immunosuppressing BALB/c mice with dexamethasone. Results Dexamethasone-immunosuppressed male mice (6–8 weeks) developed disseminated infection as evidenced by the detection of ZIKV-NS1 protein expression and high viral loads in multiple organs. They had ≥ 10% weight loss and high clinical scores soon after dexamethasone withdrawal (10 dpi), which warranted euthanasia at 12 dpi. Viral loads in blood and most tissues at 5 dpi were significantly higher than those at 12 dpi (P, Highlights • A novel mouse model for Zika virus infection using dexamethasone-immunosuppressed BALB/c mice was characterized. • The mice developed disseminated infection and dexamethasone withdrawal led to multi-organ inflammation, including orchitis. • Recombinant type I interferons improved the clinical outcome of the infected mice. Zika virus (ZIKV) is an emerging mosquito-borne virus associated with congenital malformations in infected fetuses and neurological complications in adults. The full spectrum of clinical features and the pathogenesis of ZIKV infection are incompletely understood. Most existing mouse models utilize mice which are deficient in interferon response and therefore may not be optimal for studying the role of host immune response in eliciting pathologies and evaluating interferon-based treatments in ZIKV infection. We characterized a novel and readily available ZIKV mouse model using dexamethasone-immunosuppressed mice. The mice developed disseminated infection early on, followed by abrupt clinical deterioration and inflammation of multiple organs, including the testis, soon after dexamethasone withdrawal. Treatment with recombinant type I interferons improved the clinical outcome of the mice.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus that causes severe disease in humans with case-fatality rates of up to 30%. There are currently very limited treatment options for SFTSV infection. We conducted a drug repurposing program by establishing a two-tier test system to rapidly screen a Food and Drug Administration- (FDA)-approved drug library for drug compounds with anti-SFTSV activity in vitro. We identified five drug compounds that inhibited SFTSV replication at low micromolar concentrations, including hexachlorophene, triclosan, regorafenib, eltrombopag, and broxyquinoline. Among them, hexachlorophene was the most potent with an IC50 of 1.3 &plusmn, 0.3 &micro, M and a selectivity index of 18.7. Mechanistic studies suggested that hexachlorophene was a virus entry inhibitor, which impaired SFTSV entry into host cells by interfering with cell membrane fusion. Molecular docking analysis predicted that the binding of hexachlorophene with the hydrophobic pocket between domain I and domain III of the SFTSV Gc glycoprotein was highly stable. The novel antiviral activity and mechanism of hexachlorophene in this study would facilitate the use of hexachlorophene as a lead compound to develop more entry inhibitors with higher anti-SFTSV potency and lower toxicity.

Post-translational modifications of host or viral proteins are key strategies exploited by viruses to support virus replication and counteract host immune response. SUMOylation is a post-translational modification process mediated by a family of ubiquitin-like proteins called small ubiquitin-like modifier (SUMO) proteins. Multiple sequence alignment of 78 representative flaviviruses showed that most (72/78, 92.3%) have a putative SUMO-interacting motif (SIM) at their non-structural 5 (NS5) protein&rsquo, s N-terminal domain. The putative SIM was highly conserved among 414 pre-epidemic and epidemic Zika virus (ZIKV) strains, with all of them having a putative SIM core amino acid sequence of VIDL (327/414, 79.0%) or VVDL (87/414, 21.0%). Molecular docking predicted that the hydrophobic SIM core residues bind to the &beta, 2 strand of the SUMO-1 protein, and the acidic residues flanking the core strengthen the binding through interactions with the basic surface of the SUMO protein. The SUMO inhibitor 2-D08 significantly reduced replication of flaviviruses and protected cells against ZIKV-induced cytopathic effects in vitro. A SIM-mutated ZIKV NS5 failed to efficiently suppress type I interferon signaling. Overall, these findings may suggest SUMO modification of the viral NS5 protein to be an evolutionarily conserved post-translational modification process among flaviviruses to enhance virus replication and suppress host antiviral response.

Zika virus (ZIKV) is a human-pathogenic flavivirus that has recently emerged as a global public health threat. ZIKV infection may be associated with congenital malformations in infected fetuses and severe neurological and systemic complications in infected adults. There are currently limited treatment options for ZIKV infection. AR-12 (OSU-03012) is a celecoxib derivative cellular kinase inhibitor that has broad-spectrum antiviral activities. In this study, we investigated the antiviral activity and mechanism of AR-12 against ZIKV. We evaluated the in vitro anti-ZIKV activity of AR-12, using cell protection and virus yield reduction assays, in multiple clinically relevant cell lines, and the in vivo treatment effects of AR-12 in a lethal mouse model using type I interferon receptor-deficient A129 mice. AR-12 inhibited ZIKV strains belonging to both the African and Asian/American lineages in Huh-7 and/or neuronal cells. AR12's IC50 against ZIKV was consistently, Highlights • AR-12 (OSU-03012) inhibited the replication of Zika virus strains belonging to both the Asian/American and African lineages. • AR-12 inhibited Zika virus replication in multiple cell types in vitro. • AR-12 treatment improved clinical and virological outcome of Zika virus-infected type I interferon receptor-deficient mice. • AR-12 inhibited Zika virus replication via down-regulation of protein kinase B (Akt).

Objective and Method We developed and evaluated five novel real-time RT-PCR assays targeting conserved regions in the 5’-untranslated region (5’-UTR), envelope (E’), non-structural protein 2A (NS2A), NS5, and 3’-UTR of the ZIKV genome. Results The ZIKV-5’-UTR assay exhibited the lowest in-vitro limit of detection (5-10 RNA copies/reaction and 3.0×10-1 plaque-forming units/ml). Compared to the modified version of a widely adopted RT-PCR assay targeting the ZIKV-E gene, the ZIKV-5’-UTR assay showed better sensitivity in human clinical specimens, and representative mouse specimens, including many organs which are known to be involved in human ZIKV infection but difficult to obtain in clinical settings. The ZIKV-5’-UTR assay detected ZIKV RNA in 84/84 (100.0%) ZIKV-E’-positive and an additional 30/296 (10.1%, P

This study evaluated a new multiplex kit, Luminex NxTAG Respiratory Pathogen Panel, for respiratory pathogens and compared it with xTAG RVP Fast v2 and FilmArray Respiratory Panel using nasopharyngeal aspirate specimens and culture isolates of different swine/avian-origin influenza A subtypes (H2N2, H5N1, H7N9, H5N6, and H9N2). NxTAG RPP gave sensitivity of 95.2%, specificity of 99.6%, PPV of 93.5%, and NPV of 99.7%. NxTAG RPP, xTAG RVP, and FilmArray RP had highly concordant performance among each other for the detection of respiratory pathogens. The mean analytic sensitivity (TCID50/ml) of NxTAG RPP, xTAG RVP, and FilmArray RP for detection of swine/avian-origin influenza A subtype isolates was 0.7, 41.8, and 0.8, respectively. All three multiplex assays correctly typed and genotyped the influenza viruses, except for NxTAG RRP that could not distinguish H3N2 from H3N2v. Further investigation should be performed if H3N2v is suspected to be the cause of disease. Sensitive and specific laboratory diagnosis of all influenza A viruses subtypes is especially essential in certain epidemic regions, such as Southeast Asia. The results of this study should help clinical laboratory professionals to be aware of the different performances of commercially available molecular multiplex RT-PCR assays that are commonly adopted in many clinical diagnostic laboratories.