Comparative Inactivation of Three Different Subtypes of Avian Influenza Virus by Ozonized Water.

Avian influenza virus (AIV) causes frequent outbreaks in poultry with high morbidity and mortality. The virus can survive on different fomites, resulting in indirect transmission to susceptible hosts. We investigated the inactivation by ozonated water (O3W) of three different subtypes of AIV (H4N8, H4N6, and H9N9) on seven different fomites. All subtypes were sensitive on all fomites, but there was a slight variation in the sensitivity of different subtypes. For example, AIV H9N9 showed more than 99% reduction on denim fabric, polypropylene, and Styrofoam after 3 min of exposure. More than 97% of H4N8 was eliminated from cardboard, denim fabric, and stainless steel after 3 min of exposure. Subtype H4N6 was the least sensitive; highest inactivation (98%) was seen on cardboard and polypropylene after 3 min of exposure. In conclusion, O3W can inactivate a large percentage of AIV applied to fomites within 3 min in all tested subtypes. Interestingly, an increase in contact time to 10 min did not result in an increase in the virus inactivation rate, probably because of the low half-life of ozone. Further studies are needed to determine how the residual virus can be inactivated so that it does not pose a problem to naïve birds.

Inactivación comparativa de tres subtipos diferentes del virus de la influenza aviar mediante agua ozonizada. El virus de la influenza aviar causa frecuentes brotes en aves la avicultura con alta morbilidad y mortalidad. El virus puede sobrevivir en diferentes fómites, lo que resulta en transmisión indirecta a huéspedes susceptibles. Se investigó la inactivación mediante agua ozonizada de tres subtipos diferentes del virus de la influenza aviar (H4N8, H4N6 y H9N9) en siete fómites diferentes. Todos los subtipos fueron sensibles al agua ozonizada (O3W) en todos los fómites, pero hubo una ligera variación en la sensibilidad de los diferentes subtipos. Por ejemplo, el virus subtipo H9N9 mostró una reducción de más del 99 % en tela de mezclilla, polipropileno y espuma de poliestireno después de tres minutos de exposición. Más del 97% del subtipo H4N8 se eliminó del cartón, la mezclilla y el acero inoxidable después de tres minutos de exposición. El subtipo H4N6 fue el menos sensible; La inactivación más alta (98%) se observó en cartón y polipropileno después de tres minutos de exposición. En conclusión, el agua ozonizada puede inactivar un gran porcentaje del virus de influenza aviar aplicado a fómites en tres minutos en todos los subtipos estudiados. Curiosamente, un aumento en el tiempo de contacto a 10 minutos no resultó en un aumento en la tasa de inactivación del virus, probablemente debido a la baja vida media del ozono. Se necesitan más estudios para determinar cómo se puede inactivar el virus residual para que no represente un problema para las aves susceptibles.

Broad-spectrum antiviral effect of MoringaA-loaded exosomes against IAV by mediating the GCN5-TFEB-autolysosome pathway.

Influenza virus-induced viral pneumonia is a major threat to human health, and specific therapeutic agents for viral pneumonia are still lacking. MoringaA (MA) is an anti-influenza virus active compound isolated from Moringa seeds, which can inhibit influenza virus by activating the TFEB-autophagic lysosomal pathway in host cells. In this study, we obtained exosomes from M2-type macrophages and encapsulated and delivered MA (MA-Exos), and we investigated the efficacy of MA-Exos in antiviral and viral pneumonia in vivo and in vitro, respectively. In addition, we provided insights into the mechanism by which MA-Exos regulates TFEB-lysosomal autophagy by RNA sequencing. The MA-Exos showed broad-spectrum inhibition of IAV, and significant promotion of the autophagic lysosomal pathway. Meanwhile, we found that GCN5 gene and protein were significantly down-regulated in IAV-infected cells after MA-Exos intervention, indicating its blocking the acetylation of TFEB by GCN5. In addition, MA-Exos also significantly promoted autophagy in lung tissue cells of mice with viral pneumonia. MA-Exos can inhibit and clear influenza virus by mediating the TFEB-autophagy lysosomal pathway by a mechanism related to the down-regulation of histone acetyltransferase GCN5. Our study provides a strategy for targeting MA-Exos for the treatment of viral pneumonia from both antiviral and virus-induced inflammation inhibition pathways.

Rifaximin ameliorates influenza A virus infection-induced lung barrier damage by regulating gut microbiota.

Prior research has indicated that the gut-lung-axis can be influenced by the intestinal microbiota, thereby impacting lung immunity. Rifaximin is a broad-spectrum antibacterial drug that can maintain the homeostasis of intestinal microflora. In this study, we established an influenza A virus (IAV)-infected mice model with or without rifaximin supplementation to investigate whether rifaximin could ameliorate lung injury induced by IAV and explore the molecular mechanism involved. Our results showed that IAV caused significant weight loss and disrupted the structure of the lung and intestine. The analysis results of 16S rRNA and metabolomics indicated a notable reduction in the levels of probiotics Lachnoclostridium, Ruminococcaceae_UCG-013, and tryptophan metabolites in the fecal samples of mice infected with IAV. In contrast, supplementation with 50 mg/kg rifaximin reversed these changes, including promoting the repair of the lung barrier and increasing the abundance of Muribaculum, Papillibacter and tryptophan-related metabolites content in the feces. Additionally, rifaximin treatment increased ILC3 cell numbers, IL-22 level, and the expression of RORγ and STAT-3 protein in the lung. Furthermore, our findings demonstrated that the administration of rifaximin can mitigate damage to the intestinal barrier while enhancing the expression of AHR, IDO-1, and tight junction proteins in the small intestine. Overall, our results provided that rifaximin alleviated the imbalance in gut microbiota homeostasis induced by IAV infection and promoted the production of tryptophan-related metabolites. Tryptophan functions as a signal to facilitate the activation and movement of ILC3 cells from the intestine to the lung through the AHR/STAT3/IL-22 pathway, thereby aiding in the restoration of the barrier. KEY POINTS: • Rifaximin ameliorated IAV infection-caused lung barrier injury and induced ILC3 cell activation. • Rifaximin alleviated IAV-induced gut dysbiosis and recovered tryptophan metabolism. • Tryptophan mediates rifaximin-induced ILC3 cell activation via the AHR/STAT3/IL-22 pathway.

STING Agonist Induced Innate Immune Responses Drive Anti-Respiratory Virus Activity In Vitro with Limited Antiviral Efficacy In Vivo.

The emergence of SARS-CoV-2 and seasonal outbreaks of other respiratory viruses highlight the urgent need for broad-spectrum antivirals to treat respiratory tract infections. Stimulator of interferon genes (STING) is a key component of innate immune signaling and plays a critical role in protection of the host against viral infections. Previously the STING agonist diABZI-4, a diamidobenzimidazole-based compound, demonstrated protection against SARS-CoV-2 both in vitro and in vivo. However, its broad-spectrum antiviral activity against other respiratory viruses in human airway epithelial cells, which are the primary targets of these infections, is not well established. In this study, we demonstrated that diABZI-4 stimulated robust innate immune responses protecting lung cells against a wide range of respiratory viruses, including influenza A virus (IAV), common cold coronaviruses, SARS-CoV-2, human rhinovirus (HRV), and human parainfluenza virus. diABZI-4 was highly active in physiologically relevant human airway epithelial tissues grown at the air-liquid interface, blocking replication of IAV, SARS-CoV-2, and HRV in these tissues. Furthermore, treatment of macrophages with diABZI-4 resulted in the secretion of cytokines that protected the primary airway epithelial cells from IAV infection. Despite the promising in vitro pan-antiviral activity, intranasal administration of diABZI-4 in mice provided early, but not sustained, inhibition of IAV replication in the lungs. These data highlight the complexities of the relationship between timing of STING agonist-driven inflammatory responses and viral replication dynamics, emphasizing the development challenge posed by STING agonists as potential therapeutics against respiratory viruses.

3,4,5-tri-O-caffeoylquinic acid attenuates influenza A virus induced inflammation through Toll-like receptor 3/7 activated signaling pathway.

BACKGROUND: 3,4,5-tri-O-caffeoylquinic acid (3,4,5-TCQA), a natural polyphenolic acid, has been shown to be effective against influenza A virus (IAV) infection. Although it was found to inhibit the neuraminidase of IAV, it may also perturb other cellular functions, as polyphenolic acids have shown antioxidant, anti-inflammatory and other activities. PURPOSE: This study aimed to investigate the effect of 3,4,5-TCQA at a cell level, which is critical for protecting host cell from IAV infection. STUDY DESIGN AND METHODS: We explored the effect of 3,4,5-TCQA on H292 cells infected or un-infected with Pr8 IAV. The major genes and related pathway were identified through RNA sequencing. The pathway was confirmed by qRT-PCR and western blot analysis. The anti-inflammatory activity was evaluated using nitric oxide measurement assay. RESULTS: We showed that 3,4,5-TCQA downregulated the immune response in H292 cells, and reduced the cytokine production in Pr8-infected cells, through Toll-like receptor (TLR) signaling pathway. In addition, 3,4,5-TCQA showed anti-inflammatory activity in LPS-activated RAW264.7 cells. CONCLUSION: Collectively, our results indicated that 3,4,5-TCQA suppressed inflammation caused by IAV infection through TLR3/7 signaling pathway. This provides a new insight into the antiviral mechanism of 3,4,5-TCQA.

Zanamivir and baloxavir combination to cure persistent influenza and coronavirus infections after hematopoietic stem cell transplant.

OBJECTIVES: Immunocompromised patients may experience prolonged shedding of influenza virus potentially leading to severe infections. Alternatives to monotherapy with neuraminidase inhibitors should be evaluated to entirely suppress viral replication and prevent drug-resistant mutations. METHODS: We investigated the clinical and virological evolution in a case of persistent influenza A and human coronavirus OC43 (HCoV-OC43) coinfection in a hematopoietic stem cell transplant recipient after different therapeutic strategies. RESULTS: Successive oseltamivir and zanamivir monotherapies failed to control both infections, with positive results persisting for over 110 days each. This led to the emergence of highly resistant oseltamivir strains due to neuraminidase mutations (E119V and R292K) followed by a deletion (del245-248), while maintaining sensitivity to zanamivir. The intra-host viral diversity data showed that the treatments impacted viral diversity of influenza virus, but not of HCoV-OC43. Considering the patient's underlying condition and the impact of prolonged viral shedding on pulmonary function, eradicating the influenza virus was necessary. A 10-day regimen combining zanamivir and baloxavir-marboxil effectively controlled influenza virus replication and was associated with the clearance of HCoV-OC43, finally resulting in comprehensive respiratory recovery. CONCLUSION: These observations underscore the importance of further investigating combination treatments as the primary approach to achieve influenza eradication in immunocompromised patients.

Structural characterization and bioactivity profiling of the fungal peptaibiotic tolypin reveal protective effects against influenza viruses.

In a bioprospection for new antivirals, we tested nonribosomally biosynthesized polypeptide antibiotics in MDCK II cells for their actions on influenza A and B viruses (IAV/IBV). Only tolypin, a mixture of closely related 16-residue peptaibiotics from the fungus Tolypocladium inflatum IE 1897, showed promising activity. It was selected for further investigation and structural characterization by ultrahigh performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HR-MS/MS) and ultrahigh performance liquid chromatography coupled to in-source collision-induced dissociation tandem mass spectrometry (UHPLC-isCID-HR-MS/MS), revealing 12 partially co-eluting individual peptides that were fully sequenced. Since tolypin-related efrapeptins are potent inhibitors of F1/Fo-ATPase, we screened tolypin for its toxicity against MDCK II cells and larvae of the greater wax moth Galleria mellonella. We found that a nontoxic concentration of tolypin (1 µg/mL) reduced the titer of two IBV strains by 4-5 log values, and that of an H3N2 strain by 1-2 log values, but the H1N1pdm strain was not affected. The higher concentrations of tolypin were cytostatic to MDCK II cells, shifted their metabolism from oxidative phosphorylation to glycolysis, and induced paralysis in G. mellonella, supporting the inhibition of F1/Fo-ATPase as the mode of action. Our results lay the foundations for future work to investigate the interplay between viral replication and cellular energy metabolism, as well as the development of drugs that target host factors.

Exploring the Efficacy of Peptides and Mimics against Influenza A Virus, Adenovirus, and Murine Norovirus.

The ongoing battle against viral pandemics continues, with the possibility of future outbreaks. The search for effective antiviral compounds that can combat a diverse range of viruses continues to be a focal point of research. This study investigated the efficacy of two natural antimicrobial peptides (AMPs) (lactoferricin and LL-37), two synthetic AMPs (melimine and Mel4), and nine AMP mimics (758, 1091, 1096, 1083, 610, NAPL, 3-BIPL, 4-BIPL, and Sau-22) against influenza A virus strains H1N1 and H3N2, human adenovirus 5 (HAdV-5), and murine norovirus 1 (MNV-1). These compounds were tested using virus pre-treatment, cell pre-treatment, or post-cell entry treatment assays, electron microscopy, and circular dichroism (CD), alongside evaluations of cytotoxicity against the host cells. After virus pre-treatment, the AMP mimics 610 and Sau-22 had relatively low IC50 values for influenza strains H1N1 (2.35 and 6.93 µM, respectively) and H3N2 (3.7 and 5.34 µM, respectively). Conversely, natural and synthetic AMPs were not active against these strains. For the non-enveloped viruses, the AMP Mel4 and mimic 1083 had moderate activity against HAdV-5 (Mel4 IC50 = 47.4 µM; 1083 IC50 = 47.2 µM), whereas all AMPs, but none of the mimics, were active against norovirus (LL-37 IC50 = 4.2 µM; lactoferricin IC50 = 23.18 µM; melimine IC50 = 4.8 µM; Mel4 IC50 = 8.6 µM). Transmission electron microscopy demonstrated that the mimics targeted the outer envelope of influenza viruses, while the AMPs targeted the capsid of non-enveloped viruses. CD showed that Mel4 adopted an α-helical structure in a membrane mimetic environment, but mimic 758 remained unstructured. The diverse activity against different virus groups is probably influenced by charge, hydrophobicity, size, and, in the case of natural and synthetic AMPs, their secondary structure. These findings underscore the potential of peptides and mimics as promising candidates for antiviral therapeutics against both enveloped and non-enveloped viruses.

Abietane diterpenoids from Isodon amethystoides and their biological activities.

Seven undescribed abietane diterpenoids [abietamethinols A-G (1-7)] were isolated from the twigs and leaves of Isodon amethystoides. Their structures were elucidated on the basis of spectroscopic methods including 2D NMR, and they were further confirmed by X-ray crystallographic data. Lophanic acid was considered as the precursor of 1-7 in the biosynthesis pathway hypothesis. These compounds were evaluated for their cytotoxic, anti-bacterial and anti-AIV (avian influenza virus) activities. Compound 5 showed 42.9% inhibitory activity against the cancer cell line SMMC-7721 at the concentration of 40 µM, 3 and 4 could inhibit the bacterial growth of Streptococcus sobrinus by 55.3% and 63.2% at the concentrations of 148.6 and 141.9 µM, respectively, and 4 was demonstrated with antiviral activity against AIV with the inhibitory effect of 68.4% at 25 µM.

Production of Disinfective Coating Layer to Facial Masks Supplemented with Camellia sinensis Extract.

Although usefulness of masks for protection against respiratory pathogens, accumulation of pathogens on their surface represents a source of infection spread. Here we prepared a plant extract-based disinfecting layer to be used in coating masks thus inhibiting their capacity to transmit airborne pathogens. To reach this, a polypropylene membrane base was coated with a layer of polyvinyledine difluoride polymer containing 500 µg/ml of Camellia sinensis (Black tea) methanolic extract. Direct inhibitory effects of C. sinensis were initially demonstrated against Staphylococcus aureus (respiratory bacteria), influenza A virus (enveloped virus) and adenovirus 1 (non-enveloped virus) which were directly proportional to both extract concentration and incubation time with the pathogen. This was later confirmed by the capacity of the supplemented membrane with the plant extract to block infectivity of the above mentioned pathogens, recorded % inhibition values were 61, 72 and 50 for S. aureus, influenza and adenovirus, respectively. In addition to the disinfecting capacity of the membrane its hydrophobic nature and pore size (154 nm) prevented penetration of dust particles or water droplets carrying respiratory pathogens. In summary, introducing this layer could protect users from infection and decrease infection risk upon handling contaminated masks surfaces.

Necroptosis blockade prevents lung injury in severe influenza.

Severe influenza A virus (IAV) infections can result in hyper-inflammation, lung injury and acute respiratory distress syndrome1-5 (ARDS), for which there are no effective pharmacological therapies. Necroptosis is an attractive entry point for therapeutic intervention in ARDS and related inflammatory conditions because it drives pathogenic lung inflammation and lethality during severe IAV infection6-8 and can potentially be targeted by receptor interacting protein kinase 3 (RIPK3) inhibitors. Here we show that a newly developed RIPK3 inhibitor, UH15-38, potently and selectively blocked IAV-triggered necroptosis in alveolar epithelial cells in vivo. UH15-38 ameliorated lung inflammation and prevented mortality following infection with laboratory-adapted and pandemic strains of IAV, without compromising antiviral adaptive immune responses or impeding viral clearance. UH15-38 displayed robust therapeutic efficacy even when administered late in the course of infection, suggesting that RIPK3 blockade may provide clinical benefit in patients with IAV-driven ARDS and other hyper-inflammatory pathologies.

Curcumin as a natural potential drug candidate against important zoonotic viruses and prions: A narrative review.

Zoonotic diseases are major public health concerns and undeniable threats to human health. Among Zoonotic diseases, zoonotic viruses and prions are much more difficult to eradicate, as they result in higher infections and mortality rates. Several investigations have shown curcumin, the active ingredient of turmeric, to have wide spectrum properties such as anti-microbial, anti-vascular, anti-inflammatory, anti-tumor, anti-neoplastic, anti-oxidant, and immune system modulator properties. In the present study, we performed a comprehensive review of existing in silico, in vitro, and in vivo evidence on the antiviral (54 important zoonotic viruses) and anti-prion properties of curcumin and curcuminoids in PubMed, Google Scholar, Science Direct, Scopus, and Web of Science databases. Database searches yielded 13,380 results, out of which 216 studies were eligible according to inclusion criteria. Of 216 studies, 135 (62.5%), 24 (11.1%), and 19 (8.8%) were conducted on the effect of curcumin and curcuminoids against SARS-CoV-2, Influenza A virus, and dengue virus, respectively. This review suggests curcumin and curcuminoids as promising therapeutic agents against a wide range of viral zoonoses by targeting different proteins and signaling pathways.

Compounds based on Adamantyl-substituted Amino Acids and Peptides as Potential Antiviral Drugs Acting as Viroporin Inhibitors.

The discussion has revolved around the derivatives of amino acids and peptides containing carbocycles and their potential antiviral activity in vitro against influenza A, hepatitis C viruses, and coronavirus. Studies conducted on cell cultures reveal that aminoadamantane amino acid derivatives exhibit the capacity to hinder the replication of viruses containing viroporins. Furthermore, certain compounds demonstrate potent virucidal activity with respect to influenza A/H5N1 and hepatitis C virus particles. A conceptual framework for viroporin inhibitors has been introduced, incorporating carbocyclic motifs as membranotropic carriers in the structure, alongside a functional segment comprised of amino acids and peptides. These components correspond to the interaction with the inner surface of the channel's pore or another target protein.

Inhibition of influenza A virus replication by a marine derived quinolone alkaloid targeting virus nucleoprotein.

Owing to the emergence of drug resistance and high morbidity and mortality, the need for novel anti-influenza A virus (IAV) drugs with divergent targets is highly sought after. Herein, a novel quinolone alkaloid (QLA) derived from marine fungus was discovered with broad-spectrum anti-IAV activities with low toxicity. Distinct from current anti-IAV drugs, QLA may block virus replication and viral RNA (vRNA) export from the nucleus by targeting virus nucleoprotein (NP). QLA can block the binding of chromosome region maintenance 1 to nuclear export signal 3 of NP to inhibit the nuclear export of NP and vRNP. QLA may also affect vRNP assembly by interfering with the binding of NP to RNA rather than NP oligomerization. Arg305 and Phe488-Gly490 may be required for the interaction between QLA and NP, and the binding pocket around these amino acids may be a promising target for anti-IAV drugs. Importantly, oral administration of QLA can protect the mice against IAV-induced death and weight loss, superior to the effects of the clinical drug oseltamivir. In summary, the marine derived compound QLA has the potential to be developed into a novel anti-IAV agent targeting virus NP protein in the future.

In vitro virucidal activity of the theaflavin-concentrated tea extract TY-1 against influenza A virus.

The annual spread of influenza A virus (IAV) infection is a global concern. We examined the IAV-inactivating potential of theaflavin-concentrated tea extract TY-1, which contains abundant polyphenols, including concentrated theaflavins and catechins. TY-1 exhibited concentration- and time-dependent virucidal activity against IAV. Specifically, 5.0 mg/mL TY-1 induced a 1.33 and ≥ 5.17 log10 50% tissue culture infective dose/mL reduction of the viral titer compared with dextrin as the diluent control within 30 min and 6 h reaction time, respectively. The high virucidal activity of TY-1 was attributed to the combined additive activities of multiple virucidal components, including theaflavins, which led to an investigation of the virucidal mechanism of action of TY-1. Western blotting revealed that TY-1 treatment reduced the band intensity of hemagglutinin and induced the appearance of additional high molecular mass bands/ladders. In addition, TY-1 treatment also reduced the band intensity of neuraminidase (NA). A hemagglutination assay revealed that TY-1 reduced hemagglutination activity, and an NA assay revealed reduced NA activity. These results indicated that TY-1 caused structural abnormalities in IAV spike proteins, possibly leading to their destruction. Reverse transcription polymerase chain reaction (PCR) targeting the IAV genome and electron microscopic observation of viral particles revealed that upon application of TY-1, the PCR products dissipated, which indicates that TY-1 destroyed the IAV genome, and the number of viral particles reduced. Overall, TY-1 exhibited multiple modes of IAV-inactivating activity. Our findings support the possible future practical use of TY-1 as a virucidal supplemental agent that can contribute to IAV infection control.

Role of sialylated glycans on bovine lactoferrin against influenza virus.

Influenza is a worldwide plague caused by the influenza virus (IAV) infection, which is initiated by specific recognition with sialic acids on host cell surface. Bovine lactoferrin (bLf) is a sialoglycoprotein belonging to the transferrin family, and it plays an important role in immune regulation. It also shows toxicity against cancer cells and pathogenic microorganisms including bacteria, fungi, and virus. The purpose of this study is to assess the roles of the sialylated glycans on bLf against IAV. To this end, bLf were first treated with sodium periodate to destroy its sialylated glycans. Then, the binding activity of native or desialylated bLf with various IAV was assessed by blotting assay. Finally, their ability to inhibit IAV attachment to host cells was analyzed in vitro. Our result showed that the sialylated glycans on bLf were almost completely destroyed by sodium periodate treatment. Furthermore, the binding activity of desialylated bLf to IAV and the ability to inhibit IAV mimics binding to MDCK cells were significantly reduced compared to that of native bLf. These results demonstrated that the sialylated glycans on bLf could serve as competitive substrates to block IAV attachment to host cells during the early stages of viral infection. Our findings make an important contribute for the fully understanding of the mechanism of bLf in the prevention of IAV infections and their possible applications in antiviral infection.

Short-hairpin RNAs delivered by recombinant adeno-associated virus inhibited the replication of influenza A viruses in vitro.

Antiviral short-hairpin RNAs (shRNAs) delivered by recombinant adeno-associated virus (rAAV) were investigated for their potential prophylactic and therapeutic applications related to the influenza A virus (IAV). To express shRNAs efficiently, an H1 promoter was inserted into the commercial rAAV2 system. The modified rAAV2 system could express shRNAs, and the purified rAAV was obtained at levels over 1013 viral genomes/ml and 1010 viral infection units/ml. The shNP-1496-n and shM2-925 delivered by rAAV could inhibit the replication of the H1N1 and H5N1 virus by targeting the conserved regions of the IAV nucleoprotein and matrix 2 genes in MDCK cells. The shNP-1496-n and shM2-925 expressed by rAAV could provide potent and long-term anti-H5N1 virus effects in rAAV-shRNA-enriched MDCK cells. Our findings provide a rational basis for developing RNA interference for the prevention and therapy of IAV infection.

Anti-influenza A Virus Effects and Mechanisms of Emodin and Its Analogs via Regulating PPARα/γ-AMPK-SIRT1 Pathway and Fatty Acid Metabolism.

The peroxisome proliferator-activated receptor (PPAR) α/γ-adenosine 5'-monophosphate- (AMP-) activated protein kinase- (AMPK-) sirtuin-1 (SIRT1) pathway and fatty acid metabolism are reported to be involved in influenza A virus (IAV) replication and IAV-pneumonia. Through a cell-based peroxisome proliferator responsive element- (PPRE-) driven luciferase bioassay, we have investigated 145 examples of traditional Chinese medicines (TCMs). Several TCMs, such as Polygonum cuspidatum, Rheum officinale Baillon, and Aloe vera var. Chinensis (Haw.) Berg., were found to possess high activity. We have further detected the anti-IAV activities of emodin (EMO) and its analogs, a group of common important compounds of these TCMs. The results showed that emodin and its several analogs possess excellent anti-IAV activities. The pharmacological tests showed that emodin significantly activated PPARα/γ and AMPK, decreased fatty acid biosynthesis, and increased intracellular ATP levels. Pharmaceutical inhibitors, siRNAs for PPARα/γ and AMPKα1, and exogenous palmitate impaired the inhibition of emodin. The in vivo test also showed that emodin significantly protected mice from IAV infection and pneumonia. Pharmacological inhibitors for PPARα/γ and AMPK signal and exogenous palmitate could partially counteract the effects of emodin in vivo. In conclusion, emodin and its analogs are a group of promising anti-IAV drug precursors, and the pharmacological mechanism of emodin is linked to its ability to regulate the PPARα/γ-AMPK pathway and fatty acid metabolism.

IFN-λ1 Displays Various Levels of Antiviral Activity In Vitro in a Select Panel of RNA Viruses.

Type III interferons (lambda IFNs) are a quite new, small family of three closely related cytokines with interferon-like activity. Attention to IFN-λ is mainly focused on direct antiviral activity in which, as with IFN-α, viral genome replication is inhibited without the participation of immune system cells. The heterodimeric receptor for lambda interferons is exposed mainly on epithelial cells, which limits its possible action on other cells, thus reducing the likelihood of developing undesirable side effects compared to type I IFN. In this study, we examined the antiviral potential of exogenous human IFN-λ1 in cellular models of viral infection. To study the protective effects of IFN-λ1, three administration schemes were used: 'preventive' (pretreatment); 'preventive/therapeutic' (pre/post); and 'therapeutic' (post). Three IFN-λ1 concentrations (from 10 to 500 ng/mL) were used. We have shown that human IFN-λ1 restricts SARS-CoV-2 replication in Vero cells with all three treatment schemes. In addition, we have shown a decrease in the viral loads of CHIKV and IVA with the 'preventive' and 'preventive/therapeutic' regimes. No significant antiviral effect of IFN-λ1 against AdV was detected. Our study highlights the potential for using IFN-λ as a broad-spectrum therapeutic agent against respiratory RNA viruses.

Quinazolin-derived myeloperoxidase inhibitor suppresses influenza A virus-induced reactive oxygen species, pro-inflammatory mediators and improves cell survival.

Superoxide radicals and other reactive oxygen species (ROS) are implicated in influenza A virus-induced inflammation. In this in vitro study, we evaluated the effects of TG6-44, a novel quinazolin-derived myeloperoxidase-specific ROS inhibitor, on influenza A virus (A/X31) infection using THP-1 lung monocytic cells and freshly isolated peripheral blood mononuclear cells (PBMC). TG6-44 significantly decreased A/X31-induced ROS and virus-induced inflammatory mediators in THP-1 cells (IL-6, IFN-γ, MCP-1, TNF-α, MIP-1ß) and in human PBMC (IL-6, IL-8, TNF-α, MCP-1). Interestingly, TG6-44-treated THP-1 cells showed a decrease in percent cells expressing viral nucleoprotein, as well as a delay in translocation of viral nucleoprotein into the nucleus. Furthermore, in influenza A virus-infected cells, TG6-44 treatment led to suppression of virus-induced cell death as evidenced by decreased caspase-3 activation, decreased proportion of Annexin V+PI+ cells, and increased Bcl-2 phosphorylation. Taken together, our results demonstrate the anti-inflammatory and anti-infective effects of TG6-44.