Nonclinical safety assessment and immunogenicity of rVSVInd(GML)-mspSGtc vaccine for SARS-CoV-2 in rabbits.

The worldwide health, economic, and societal consequences of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic have been devastating. The primary strategy to prevent new infectious diseases is to vaccinate the majority of people worldwide. However, the significant hurdles that are faced include vaccine safety concerns and vaccine reluctance. Among the various types of vaccines, the recombinant vesicular stomatitis virus (rVSV) is a promising candidate owing to its safety and efficacy. Therefore, we investigated the toxicity, immunogenicity, and local tolerance of the rVSVInd(GML)-mspSGtc vaccine against SARS-CoV-2. New Zealand White (NZW) rabbits were administered single or three repeated intramuscular injections of rVSVInd(GML)-mspSGtc every 2 weeks, followed by a 4-week recovery period. Male and female rabbits were randomly assigned into three groups: a control group and two dose-level groups (1 × 109 and 4 × 109 PFU/mL). Treatment-related changes included a temporary increase in body temperature and local inflammation at the injection site. These findings indicated recovery or a trend toward recovery, with no overt systemic toxicity. Immunogenicity analysis results suggested that rVSVInd(GML)-mspSGtc elicited a robust dose-dependent immune response in terms of neutralizing antibodies and IgG antibodies against the SARS-CoV-2 spike protein. In addition, the immune response intensity was increased by repeated vaccine administration. In conclusion, both the approximate lethal dose and the no observed adverse effect level for rVSVInd(GML)-mspSGtc exceeded 4 × 109 PFU/mL in NZW rabbits. Overall, rVSVInd(GML)-mspSGtc induced no adverse effects at the maximum dosage tested; however, its efficacy warrants further clinical evaluation.

Preclinical evaluation of general toxicity and safety pharmacology of a receptor-binding domain-based COVID-19 subunit vaccine in various animal models.

The coronavirus disease 2019 pandemic has resulted in the introduction of several naïve methods of vaccine development, which have been used to prepare novel viral vectors and mRNA-based vaccines. However, reluctance to receive vaccines owing to the uncertainty regarding their safety is prevalent. Therefore, rigorous safety evaluation of vaccines through preclinical toxicity studies is critical to determine the safety profiles of vaccine candidates. This study aimed to evaluate the toxicity profile of HuVac-19, a subunit vaccine of SARS-CoV-2 utilizing the receptor-binding domain as an antigen, in rats, rabbits, and dogs using single- and repeat-dose study designs. Repeat-dose toxicity studies in rats and rabbits showed transient changes in hematological and serum biochemical parameters in the adjuvant and/or vaccine groups; however, these changes were reversed or potentially reversible after the recovery period. Moreover, temporary reversible changes in absolute and relative organ weights were observed in the prostate of rats and the thymus of rabbits. Gross examination of the injection sites in rats and rabbits treated with the adjuvant- and HuVac-19 showed discoloration and foci, whereas histopathological examination showed granulomatous inflammation, inflammatory cell infiltration, and myofiber degeneration/necrosis. This inflammatory response was local, unassociated with other toxicological changes, and resolved. In a pharmacological safety study, no toxicological or physiological changes associated with HuVac-19 administration were observed. In conclusion, HuVac-19 was not associated with any major systemic adverse effects in the general toxicity and safety pharmacology evaluation, demonstrating that HuVac-19 is a vaccine candidate with sufficient capacity to be used in human clinical trials.

Novel SARS-CoV-2 entry inhibitors, 2-anilinoquinazolin-4(3H)-one derivatives, show potency as SARS-CoV-2 antivirals in a human ACE2 transgenic mouse model.

The ongoing COVID-19 has not only caused millions of deaths worldwide, but it has also led to economic recession and the collapse of public health systems. The vaccines and antivirals developed in response to the pandemic have improved the situation markedly; however, the pandemic is still not under control with recurring surges. Thus, it is still necessary to develop therapeutic agents. In our previous studies, we designed and synthesized a series of novel 2-anilinoquinazolin-4(3H)-one derivatives, and demonstrated inhibitory activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and MERS-CoV in vitro. We then conducted in vivo studies using modified compounds that are suitable for oral administration. These compounds demonstrated no toxicity in rats and inhibited viral entry. Here, we investigated the in vivo efficacy of these drug candidates against SARS-CoV-2. Three candidate drugs, 7-chloro-2-((3,5-dichlorophenyl)amino)quinazolin-4(3H)-one (1), N-(7-chloro-4-oxo-3,4-dihydroquinazolin-2-yl)-N-(3,5-dichlorophenyl)acetamide (2), and N-(7-chloro-4-oxo-3,4-dihydroquinazolin-2-yl)-N-(3,5-difluorophenyl)acetamide (3) were administered orally to hACE2 transgenic mice at a dose of 100 mg/kg. All three drugs improved survival rate and reduced the viral load in the lungs. These results show that the derivatives possess in vivo antiviral efficacy similar to that of molnupiravir, which is currently being used to treat COVID-19. Overall, our data suggest that 2-anilinoquinazolin-4(3H)-one derivatives are promising as potential oral antiviral drug candidates against SARS-CoV-2 infection.

Preclinical safety assessment of the suction-assisted intradermal injection of the SARS-CoV-2 DNA vaccine candidate pGO-1002 in white rabbit.

pGO-1002, a non-viral DNA vaccine that expresses both spike and ORF3a antigens of SARS-CoV-2, is undergoing phase 1 and phase 2a clinical trials in Korea and the US. A preclinical repeated-dose toxicity study in New Zealand white rabbits in compliance with Good Laboratory Practice (GLP) was conducted to assess the potential toxicity, local tolerance, and immunogenicity of the vaccine and GeneDerm suction device. The dose rate was 1.2 mg/head pGO-1002, and this was administered intradermally to a group of animals (eight animals/sex/group) three times at 2-week intervals, followed by a 4-week recovery period. After each administration, suction was applied to the injection site using the GeneDerm device. Mortality, clinical signs, body weight, food consumption, skin irritation, ophthalmology, body temperature, urinalysis, and clinical pathology were also monitored. Gross observations and histopathological evaluation were performed. Overall, pGO-1002 administration-related changes were confined to minor damage or changes at the injection site, increased spleen weight and minimal increased cellularity in white pulp. All changes of injection site were considered local inflammatory changes or pharmacological actions due to the vaccine with the changes in spleen considered consistent with vaccine-induced immune activation. All findings showed reversibility during the 4-week recovery period. Animals vaccinated with pGO-1002, administered by intradermal injection and followed by application of suction with GeneDerm, developed humoral and cellular responses against the SARS-CoV-2 antigens consistent with prior studies in rats. Collectively, it was concluded that the pGO-1002 vaccine was safe and effective under these experimental conditions and these data supported future human study of the vaccine, now known as GLS-5310, for clinical trial use.

The Relationship between Burrow Opening Dimensions and Biomass of Intertidal Macroinvertebrates by Feeding Mode (Surface Deposit Feeders vs. Suspension Feeders).

Biomass and abundance are fundamental parameters in ecology, conservation biology, and environmental impact assessment. Distinguishing features, such as burrow openings and feeding pellets, made by different intertidal macroinvertebrate species on the surface are used as proxies to establish the abundance of intertidal macroinvertebrates. This study investigated the feasibility of estimating biomass from the burrow opening dimensions as a proxy. We analyzed the relationship between the burrow opening dimensions and body weights of intertidal macroinvertebrates and compared surface deposit feeders with suspension feeders. Regression analysis evaluated the relationship between burrow opening diameter, body size, and biomass. The diameters of surface deposit feeder burrow openings were significantly related to biomass, but this was not the case for suspension feeders. Our results indicate that burrow opening dimensions can be used as a proxy to estimate the biomass of surface deposit feeders. However, additional studies are needed to clarify further the relationship between the burrow opening diameter and biomass of the suspension feeders. This is a preliminary study to spatially quantify the biomass of intertidal macroinvertebrates by extracting the dimension of burrow openings from drone images through object detection tools.

Optimization of 2-Aminoquinazolin-4-(3H)-one Derivatives as Potent Inhibitors of SARS-CoV-2: Improved Synthesis and Pharmacokinetic Properties.

We previously reported the potent antiviral effect of the 2-aminoquinazolin-4-(3H)-one 1, which shows significant activity (IC50 = 0.23 µM) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with no cytotoxicity. However, it is necessary to improve the in vivo pharmacokinetics of compound 1 because its area under the curve (AUC) and maximum plasma concentration are low. Here, we designed and synthesized N-substituted quinazolinone derivatives that had good pharmacokinetics and that retained their inhibitory activity against SARS-CoV-2. These compounds were conveniently prepared on a large scale through a one-pot reaction using Dimroth rearrangement as a key step. The synthesized compounds showed potent inhibitory activity, low binding to hERG channels, and good microsomal stability. In vivo pharmacokinetic studies showed that compound 2b had the highest exposure (AUC24h = 41.57 µg∙h/mL) of the synthesized compounds. An in vivo single-dose toxicity evaluation of compound 2b at 250 and 500 mg/kg in rats resulted in no deaths and an approximate lethal dose greater than 500 mg/kg. This study shows that N-acetyl 2-aminoquinazolin-4-(3H)-one 2b is a promising lead compound for developing anti-SARS-CoV-2 agents.

Synthesis and biological evaluation of 2-benzylaminoquinazolin-4(3H)-one derivatives as a potential treatment for SARS-CoV-2.

Despite the continuing global crisis caused by coronavirus disease 2019 (COVID-19), there is still no effective treatment. Therefore, we designed and synthesized a novel series of 2-benzylaminoquinazolin-4(3H)-one derivatives and demonstrated that they are effective against SARS-CoV-2. Among the synthesized derivatives, 7-chloro-2-(((4-chlorophenyl)(phenyl)methyl)amino)quinazolin-4(3H)-one (Compound 39) showed highest anti-SARS-CoV-2 activity, with a half-maximal inhibitory concentration value greater than that of remdesivir (IC50 = 4.2 µM vs. 7.6 µM, respectively), which gained urgent approval from the U.S. Food and Drug Administration. In addition, Compound 39 showed good results in various assays measuring metabolic stability, human ether a-go-go, Cytochromes P450 (CYPs) inhibition, and plasma protein binding (PPB), and showed better solubility and pharmacokinetics than our previous work.

Anticoronaviral Activity of the Natural Phloroglucinols, Dryocrassin ABBA and Filixic Acid ABA from the Rhizome of Dryopteris crassirhizoma by Targeting the Main Protease of SARS-CoV-2.

The rhizome of Dryopteris crassirhizoma Nakai. (Dryopteridaceae) has been used in traditional medicine in East Asia and has recently been reported to have anticancer, anti-inflammation, and antibacterial activity as well as antiviral activity. Natural phloroglucinols from D. crassirhizoma, dryocrassin ABBA and filixic acid ABA were reported to inhibit influenza virus infection with an inhibitory activity on neuraminidase. In this study, we found that dryocrassin ABBA and filixic acid ABA have an inhibitory activity against the main protease of SARS-CoV-2. Therefore, dryocrassin ABBA and filixic acid ABA exhibited inhibitory activity against SARS-CoV-2 infection in Vero cells dose-dependently using the immunofluorescence-based antiviral assays. Moreover, these compounds inhibited SARS-CoV and MERS-CoV infection, suggesting their broad-spectrum anticoronaviral activity. In addition, a 5-day repeated-dose toxicity study of dryocrassin ABBA and filixic acid ABA suggested that an approximately lethal dose of these compounds in mice was >10 mg/kg. Pharmacokinetic studies of dryocrassin ABBA showed good microsomal stability, low hERG inhibition, and low CYP450 inhibition. In vivo pharmacokinetic properties of dryocrassin ABBA showed a long half-life (5.5-12.6 h) and high plasma exposure (AUC 19.3-65 µg·h/mL). Therefore, dryocrassin ABBA has therapeutic potential against emerging coronavirus infections, including COVID-19.

Broad Spectrum Antiviral Properties of Cardiotonic Steroids Used as Potential Therapeutics for Emerging Coronavirus Infections.

Cardiotonic steroids are steroid-like natural compounds known to inhibit Na+/K+-ATPase pumps. To develop a broad-spectrum antiviral drug against the emerging coronavirus infection, this study assessed the antiviral properties of these compounds. The activity of seven types of cardiotonic steroids against the MERS-CoV, SARS-CoV, and SARS-CoV-2 coronavirus varieties was analyzed using immunofluorescence antiviral assay in virus-infected cells. Bufalin, cinobufagin, and telocinobufagin showed high anti-MERS-CoV activities (IC50, 0.017~0.027 µM); bufalin showed the most potent anti-SARS-CoV and SARS-CoV-2 activity (IC50, 0.016~0.019 µM); cinobufotalin and resibufogenin showed comparatively low anti-coronavirus activity (IC50, 0.231~1.612 µM). Differentially expressed genes in Calu3 cells treated with cinobufagin, telocinobufagin, or bufalin, which had high antiviral activity during MERS-CoV infection were analyzed using QuantSeq 3' mRNA-Seq analysis and data showed similar gene expression patterns. Furthermore, the intraperitoneal administration of 10 mg/kg/day bufalin, cinobufagin, or digitoxin induced 100% death after 1, 2, and 4 days in 5-day repeated dose toxicity studies and it indicated that bufalin had the strongest toxicity. Pharmacokinetic studies suggested that telocinobufagin, which had high anti-coronavirus activity and low toxicity, had better microsomal stability, lower CYP inhibition, and better oral bioavailability than cinobufagin. Therefore, telocinobufagin might be the most promising cardiotonic steroid as a therapeutic for emerging coronavirus infections, including COVID-19.

Bavachin produces immunoadjuvant activity by targeting the NFAT signaling pathway.

BACKGROUND: Bavachin, a flavonoid compound isolated from the seeds and fruits of Psoralea corylifolia l. (family Fabaceae), is used as a traditional medicine in Asia. Indeed, it is reported to have various medicinal functions such as estrogenic and antiinflammatory activities among others. However, to date, the effects of bavachin on T cell activation have yet to be reported. PURPOSE AND STUDY DESIGN: We aimed to determine the effects of bavachin on the activation of a human T cell line in vitro and on antigen-specific immune responses in mice in vivo. METHODS: In a nuclear factor of activated T cells (NFAT) activity assay, the Jurkat T cell line expressing a luciferase reporter driven by an NFAT-response element was stimulated with antihuman CD3/CD28 antibody and bavachin. Furthermore, the level of cytokine production was measured in the Jurkat T cell line stimulated with phorbol 12-myristate 13-acetate/ionomycin and bavachin using an IL-2 ELISA and a cytometric bead array assay. For in vivo analyses, mice were subcutaneously immunized with an antigen (ovalbumin protein) and bavachin, and the immune responses of mice were analyzed by FACS analysis, a T cell proliferation assay, a cytokine ELISA, and an antiovalbumin-specific antibody ELISA. RESULTS: We found that bavachin activated NFAT-mediated transcription in the human T cell line in vitro. In mice, when bavachin was administered with the antigen, an increase in T cell responses and antibody production specific to the antigen was observed. CONCLUSION: Our results suggest that bavachin has immunoadjuvant and immunomodulation effects, which arise through activation of the NFAT signaling pathway.

Safety evaluation of fermented Platycodon grandiflorus (Jacq.) A.DC. extract: Genotoxicity, acute toxicity, and 13-week subchronic toxicity study in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Platycodon grandiflorus (Jacq.) A.DC. is a well-known traditional herbal medicine administered for bronchitis and inflammatory diseases. Especially, anti-inflammatory effect of fermented P. grandiflorus (Jacq.) A.DC. extract (FPGE) was higher than that of P. grandiflorus (Jacq.) A.DC. extract. However, toxicological information for FPGE is lacking. AIM OF THE STUDY: In this study, we establish a toxicological profile for FPGE by testing genotoxicity, acute and 13-week subchronic toxicity. MATERIALS AND METHODS: FPGE was evaluated with bacterial reverse mutation, chromosome aberration, and micronucleus test. For the acute- and 13-week subchronic toxicity tests, FPGE was administered orally at doses of 0, 750, 1500, and 3000 mg/kg in SD rats. RESULTS: The results of the genotoxic assays indicated that FPGE induced neither mutagenicity nor clastogenicity. The acute toxicity test showed that FPGE did not affect animal mortality, clinical signs, body weight changes, or microscopic findings at ≤ 3000 mg/kg. The approximate lethal dose (ALD) of FPGE in SD rats was >3000 mg/kg. For the 13-week subchronic toxicity assay, no FPGE dose induced any significant change in mortality, clinical signs, body or organ weight, food consumption, ophthalmology, urinalysis, hematology, serum chemistry, gross findings and histopathologic examination in either SD rat sex. The rat no observed adverse effects level (NOAEL) for FPGE was set to 3000 mg/kg. CONCLUSIONS: The present study empirically demonstrated that FPGE has a safe preclinical profile and indicated that it could be safely integrated into health products for atopic dermatitis treatment.

Design, synthesis and biological evaluation of 2-aminoquinazolin-4(3H)-one derivatives as potential SARS-CoV-2 and MERS-CoV treatments.

Despite the rising threat of fatal coronaviruses, there are no general proven effective antivirals to treat them. 2-Aminoquinazolin-4(3H)-one derivatives were newly designed, synthesized, and investigated to show the inhibitory effects on SARS-CoV-2 and MERS-CoV. Among the synthesized derivatives, 7-chloro-2-((3,5-dichlorophenyl)amino)quinazolin-4(3H)-one (9g) and 2-((3,5-dichlorophenyl)amino)-5-hydroxyquinazolin-4 (3H)-one (11e) showed the most potent anti-SARS-CoV-2 activities (IC50 < 0.25 µM) and anti-MERS-CoV activities (IC50 < 1.1 µM) with no cytotoxicity (CC50 > 25 µM). In addition, both compounds showed acceptable results in metabolic stabilities, hERG binding affinities, CYP inhibitions, and preliminary PK studies.

A Robot Operating System Framework for Secure UAV Communications.

To perform advanced operations with unmanned aerial vehicles (UAVs), it is crucial that components other than the existing ones such as flight controller, network devices, and ground control station (GCS) are also used. The inevitable addition of hardware and software to accomplish UAV operations may lead to security vulnerabilities through various vectors. Hence, we propose a security framework in this study to improve the security of an unmanned aerial system (UAS). The proposed framework operates in the robot operating system (ROS) and is designed to focus on several perspectives, such as overhead arising from additional security elements and security issues essential for flight missions. The UAS is operated in a nonnative and native ROS environment. The performance of the proposed framework in both environments is verified through experiments.

Preclinical safety assessment of a therapeutic human papillomavirus DNA vaccine combined with intravaginal interleukin-7 fused with hybrid Fc in female rats.

This study was conducted to establish the toxicological profile of combination treatment with therapeutic HPV DNA vaccines (GX-188E) and the long-acting form of recombinant human interleukin-7 fused with hybrid Fc (IL-7hyFc). GX-188E was administered intramuscularly by electroporation with or without IL-7hyFc intravaginally once per 2 weeks for 8 weeks (five times) in female Sprague-Dawley rats. Because up-regulation of immune responses and migration of antigen-specific T cells in cervicoviginal tissue were predicted as therapeutic effects, we distinguished adverse effects from therapeutic effects based on the severity of the systemic immune response, reversibility of lymphoid tissue changes, target tissue damage, and off-target immune responses. We observed that the number of neutrophils was increased, and the number of lymphocytes was decreased in the blood. Further, myofiber degeneration, necrosis, fibroplasia, and cell infiltration were observed at the GX-188E administration site. These changes were fully or partially recovered over a 4-week period. Analysis of lymphocytes in spleen revealed that CD4+ T cells and total T cells decreased in rats treated with GX-188E in combination with a high dose of IL-7hyFc (1.25 mg/animal). However, these changes were not considered adverse because they were transient and may have been related to electroporation-mediated DNA delivery or the local migration of lymphocytes induced by IL-7. Therefore, the potential toxicity of the combination of GX-188E and IL-7hyFc treatment was comparable to that of GX-188E treatment alone, and the no observed adverse effect level for GX-188E with IL-7hyFc was considered as 320 µg/animal for GX-188E and 1.25 mg/animal for IL-7hyFc.

Lycorine, a non-nucleoside RNA dependent RNA polymerase inhibitor, as potential treatment for emerging coronavirus infections.

BACKGROUND: Highly effective novel treatments need to be developed to suppress emerging coronavirus (CoV) infections such as COVID-19. The RNA dependent RNA polymerase (RdRp) among the viral proteins is known as an effective antiviral target. Lycorine is a phenanthridine Amaryllidaceae alkaloid isolated from the bulbs of Lycoris radiata (L'Hér.) Herb. and has various pharmacological bioactivities including antiviral function. PURPOSE: We investigated the direct-inhibiting action of lycorine on CoV's RdRp, as potential treatment for emerging CoV infections. METHODS: We examined the inhibitory effect of lycorine on MERS-CoV, SARS-CoV, and SARS-CoV-2 infections, and then quantitatively measured the inhibitory effect of lycorine on MERS-CoV RdRp activity using a cell-based reporter assay. Finally, we performed the docking simulation with lycorine and SARS-CoV-2 RdRp. RESULTS: Lycorine efficiently inhibited these CoVs with IC50 values of 2.123 ± 0.053, 1.021 ± 0.025, and 0.878 ± 0.022 µM, respectively, comparable with anti-CoV effects of remdesivir. Lycorine directly inhibited MERS-CoV RdRp activity with an IC50 of 1.406 ± 0.260 µM, compared with remdesivir's IC50 value of 6.335 ± 0.731 µM. In addition, docking simulation showed that lycorine interacts with SARS-CoV-2 RdRp at the Asp623, Asn691, and Ser759 residues through hydrogen bonding, at which the binding affinities of lycorine (-6.2 kcal/mol) were higher than those of remdesivir (-4.7 kcal/mol). CONCLUSIONS: Lycorine is a potent non-nucleoside direct-acting antiviral against emerging coronavirus infections and acts by inhibiting viral RdRp activity; therefore, lycorine may be a candidate against the current COVID-19 pandemic.

Discovery of cyclic sulfonamide derivatives as potent inhibitors of SARS-CoV-2.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) continues to spread worldwide, with 25 million confirmed cases and 800 thousand deaths. Effective treatments to target SARS-CoV-2 are urgently needed. In the present study, we have identified a class of cyclic sulfonamide derivatives as novel SARS-CoV-2 inhibitors. Compound 13c of the synthesized compounds exhibited robust inhibitory activity (IC50 = 0.88 µM) against SARS-CoV-2 without cytotoxicity (CC50 > 25 µM), with a selectivity index (SI) of 30.7. In addition, compound 13c exhibited high oral bioavailability (77%) and metabolic stability with good safety profiles in hERG and cytotoxicity studies. The present study identified that cyclic sulfonamide derivatives are a promising new template for the development of anti-SARS-CoV-2 agents.

Identification of 4-anilino-6-aminoquinazoline derivatives as potential MERS-CoV inhibitors.

New therapies for treating coronaviruses are urgently needed. A series of 4-anilino-6-aminoquinazoline derivatives were synthesized and evaluated to show high anti-MERS-CoV activities. N4-(3-Chloro-4-fluorophenyl)-N6-(3-methoxybenzyl)quinazoline-4,6-diamine (1) has been identified in a random screen as a hit compound for inhibiting MERS-CoV infection. Throughout optimization process, compound 20 was found to exhibit high inhibitory effect (IC50 = 0.157 µM, SI = 25) with no cytotoxicity and moderate in vivo PK properties.

Natural Bis-Benzylisoquinoline Alkaloids-Tetrandrine, Fangchinoline, and Cepharanthine, Inhibit Human Coronavirus OC43 Infection of MRC-5 Human Lung Cells.

Stephaniatetrandra and other related species of Menispermaceae are the major sources of the bis-benzylisoquinoline alkaloids tetrandrine (TET), fangchinoline (FAN), and cepharanthine (CEP). Although the pharmacological properties of these compounds include anticancer and anti-inflammatory activities, the antiviral effects of these compounds against human coronavirus (HCoV) remain unclear. Hence, the aims of the current study were to assess the antiviral activities of TET, FAN, and CEP and to elucidate the underlying mechanisms in HCoV-OC43-infected MRC-5 human lung cells. These compounds significantly inhibited virus-induced cell death at the early stage of virus infection. TET, FAN, and CEP treatment dramatically suppressed the replication of HCoV-OC43 as well as inhibited viral S and N protein expression. The virus-induced host response was reduced by compound treatment as compared with the vehicle control. Taken together, these findings demonstrate that TET, FAN, and CEP are potential natural antiviral agents for the prevention and treatment of HCoV-OC43 infection.

Synthesis and biological evaluation of 3-acyl-2-phenylamino-1,4-dihydroquinolin-4(1H)-one derivatives as potential MERS-CoV inhibitors.

3-Acyl-2-phenylamino-1,4-dihydroquinolin-4(1H)-one derivatives were synthesized and evaluated to show high anti-MERS-CoV inhibitory activities. Among them, 6,8-difluoro-3-isobutyryl-2-((2,3,4-trifluorophenyl)amino)quinolin-4(1H)-one (6u) exhibits high inhibitory effect (IC50 = 86 nM) and low toxicity (CC50 > 25 µM). Moreover, it shows good metabolic stability, low hERG binding affinity, no cytotoxicity, and good in vivo PK properties.

Bacterial Outer Membrane Vesicles Provide Broad-Spectrum Protection against Influenza Virus Infection via Recruitment and Activation of Macrophages.

Influenza A virus (IAV) poses a constant worldwide threat to human health. Although conventional vaccines are available, their protective efficacy is type or strain specific, and their production is time-consuming. For the control of an influenza pandemic in particular, agents that are immediately effective against a wide range of virus variants should be developed. Although pretreatment of various Toll-like receptor (TLR) ligands have already been reported to be effective in the defense against subsequent IAV infection, the efficacy was limited to specific subtypes, and safety concerns were also raised. In this study, we investigated the protective effect of an attenuated bacterial outer membrane vesicle -harboring modified lipid A moiety of lipopolysaccharide (fmOMV) against IAV infection and the underlying mechanisms. Administration of fmOMV conferred significant protection against a lethal dose of pandemic H1N1, PR8, H5N2, and highly pathogenic H5N1 viruses; this broad antiviral activity was dependent on macrophages but independent of neutrophils. fmOMV induced recruitment and activation of macrophages and elicited type I IFNs. Intriguingly, fmOMV showed a more significant protective effect than other TLR ligands tested in previous reports, without exhibiting any adverse effect. These results show the potential of fmOMV as a prophylactic agent for the defense against influenza virus infection.