Treatment Of Influenza Infections Research Articles

Stereoselective Synthesis of Baloxavir Marboxil Using Diastereoselective Cyclization and Photoredox Decarboxylation of l-Serine.

Baloxavir marboxil (1; BXM) is a potent drug used for treating influenza infections. The current synthetic route to BXM (1) is based on optical resolution; however, this method results in the loss of nearly 50% of the material. This study aimed to describe an efficient and simpler method for the synthesis of BXM. We achieved a stereoselective synthesis of BXM (1). The tricyclic triazinanone core possessing a chiral center was prepared via diastereoselective cyclization utilizing the readily available amino acid l-serine. The carboxyl moiety derived from l-serine was removed via photoredox decarboxylation under mild conditions to furnish the chiral tricyclic triazinanone core ((R)-14). The synthetic route demonstrated herein provides an efficient and atomically economical method for preparing this potent anti-influenza agent.

The effect of oral administration of tauroside Sx1 on the accumulation of influenza virus and histological changes in the lungs of mice

The constant threat of a new viral pandemic gives special urgency to the search for new effective means of preventing and treating influenza infection. The article examines the effect of oral administration of saponin tauroside Sx1, obtained from the leaves of Crimean ivy, on the development of infection caused by influenza virus A/WSN/1/33(H1N1), and histological changes in the lungs of infected mice. It was revealed that oral administration of saponin tauroside Sx1 at a dose of 200 mcg/mouse day or 11.8 mg/kg/day for three days after infection led to an almost twofold statistically significant increase in the average life expectancy of infected animals from 6.50±0.67 to 11.10±2.19 days. The protective activity of tauroside Sx1 was established when administered orally in the early stages of influenza infection in mice. The protective effect of saponin is manifested in a significant increase in the average life expectancy and normalization of the structure of lung tissue in infected animals. The results obtained indicate the prospects for further study of saponin tauroside Sx1 as a potential component of anti-influenza drugs.

Sodium taurocholate hydrate inhibits influenza virus replication and suppresses influenza a Virus-triggered inflammation in vitro and in vivo.

Influenza A virus is an important respiratory pathogen that poses serious threats to human health. Owing to the high mutation rate of viral genes, weaker cross-protection of vaccines, and rapid emergence of drug resistance, there is an urgent need to develop new antiviral drugs against influenza viruses. Taurocholic acid is a primary bile acid that promotes digestion, absorption, and excretion of dietary lipids. Here, we demonstrate that sodium taurocholate hydrate (STH) exhibits broad-spectrum antiviral activity against influenza strains H5N6, H1N1, H3N2, H5N1, and H9N2 in vitro. STH significantly inhibited the early stages of influenza A virus replication. The levels of influenza virus viral RNA (vRNA), complementary RNA (cRNA), and mRNA were specifically reduced in virus-infected cells following STH treatment. In vivo, STH treatment of infected mice alleviated clinical signs and reduced weight loss and mortality. STH also reduced TNF-α, IL-1β, and IL-6 overexpression. STH significantly inhibited the upregulation of TLR4 and the NF-kB family member p65, both in vivo and in vitro. These results suggest that STH exerts a protective effect against influenza infection via suppression of the NF-kB pathway, highlighting the potential use of STH as a drug for treating influenza infection.

Neuraminidase Inhibitors: Development and Validation of a Procedure for <i>In Vitro</i> Determination of the Inhibitory Effect

Neuraminidase inhibitors are a class of antivirals used to treat influenza infections. Screening assays for potential neuraminidase inhibitors would benefit from the development of in vitro procedures that do not require handling viruses. The aim of the study was to develop and validate a procedure for in vitro determination of inhibitory effects on neuraminidase (EC 3.2.1.18), using 2’-4(methylumbelliferyl)-α-D-N-acetylneuraminic acid (4MU-NANA) as a fluorogenic substrate and quinonoid pigments, potential neuraminidase inhibitors, as a case study. Materials and methods: the method is based on neuraminidase cleavage of 4MU-NANA to release fluorescent 4-methylumbelliferone, which is detected at the excitation and emission wavelengths of 360 and 450 nm, respectively. Results: the procedure was validated for specificity, range, accuracy, and precision. It remained linear over the range of 0.31–80 μM of 4-methylumbelliferone. The accuracy for four concentration levels (including the LLOQ) was 87–114%; i.e., the relative error of accuracy evaluation was less than 15%. The intra- and inter-day precision ranged from 1.5 to 10.4% and from 2.3 to 9.6%, respectively. Inhibitory effect evaluation using zanamivir hydrate (0.6–150 nM) demonstrated the accuracy of 89–120% and the precision of 3.1–11.0%. The IC50 values for positive controls (zanamivir hydrate and oseltamivir) were 27 ± 3 and 16 ± 2 nM, respectively. The following solvents may be used: 50% dimethyl sulfoxide, 5% Polysorbate 80, 50% ethanol, 50 and 100% methanol. If a compound is insoluble in the solvents, it is possible to form inclusion complexes with 2-hydroxypropyl-β-cyclodextrin. For bisnaphthazarin, the natural quinonoid pigment used in the study, the IC50 amounted to 273 ± 28 nМ. Conclusion: the procedure demonstrated adequate accuracy and reproducibility and is recommended for screening for potential neuraminidase inhibitors. In order to use the procedure for insoluble substances, the authors suggest forming inclusion complexes with cyclodextrins.

Network pharmacology associated anti-influenza mechanism research of Qingjie-Tuire Granule via STAT1/3 signaling pathway

Qingjie-Tuire (QT) granule was approved for clinical use and its combination was reported to treat influenza infection. To explore its active component and mechanism, the components of QT granule were retrieved from UPLC-UC-Q-TOF/MS analysis. The genes corresponding to the targets were retrieved using GeneCards and TTD database. The herb–compound–target network was constructed by Cytoscape. The target protein–protein interaction network was built using STRING database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of QT granule to IAV were performed for further study. The regulation to different signaling transduction events and cytokine/chemokine expression of QT granule was evaluated using Western blotting and real-time qPCR. Totally, 47 compounds were identified and effect of QT granule on cell STAT1/3 signaling pathways was confirmed by A549 cell model. The efficiency of QT granule on host cell contributes to its clinical application and mechanism research.

Risk Factors for Influenza-Induced Exacerbations and Mortality in Non-Cystic Fibrosis Bronchiectasis.

Influenza infection is a cause of exacerbations in patients with chronic pulmonary diseases. The aim of this study was to investigate the clinical outcomes and identify risk factors associated with hospitalization and mortality following influenza infection in adult patients with bronchiectasis. Using the Chang Gung Research Database, we identified patients with bronchiectasis and influenza-related infection (ICD-9-CM 487 and anti-viral medicine) between 2008 and 2017. The main outcomes were influenza-related hospitalization and in-hospital mortality rate. Eight hundred sixty-five patients with bronchiectasis and influenza infection were identified. Five hundred thirty-six (62%) patients with bronchiectasis were hospitalized for influenza-related infection and 118 (22%) patients had respiratory failure. Compared to the group only seen in clinic, the hospitalization group was older, with more male patients, a lower FEV1, higher bronchiectasis aetiology comorbidity index (BACI), and more acute exacerbations in the previous year. Co-infections were evident in 55.6% of hospitalized patients, mainly caused by Pseudomonas aeruginosa (15%), fungus (7%), and Klebsiella pneumoniae (6%). The respiratory failure group developed acute kidney injury (36% vs. 16%; p < 0.001), and shock (47% vs. 6%; p < 0.001) more often than influenza patients without respiratory failure. The overall mortality rate was 10.8% and the respiratory failure group exhibited significantly higher in-hospital mortality rates (27.1% vs. 6.2%; p < 0.001). Age, BACI, and previous exacerbations were independently associated with influenza-related hospitalization. Age, presence of shock, and low platelet counts were associated with increased hospital mortality. Influenza virus caused severe exacerbation in bronchiectasis, especially in those who were older and who had high BACI scores and previous exacerbations. A high risk of respiratory failure and mortality were observed in influenza-related hospitalization in bronchiectasis. We highlight the importance of preventing or treating influenza infection in bronchiectasis.

Effect of Structural Differences in Naringenin, Prenylated Naringenin, and Their Derivatives on the Anti-Influenza Virus Activity and Cellular Uptake of Their Flavanones.

Vaccines and antiviral drugs are widely used to treat influenza infection. However, they cannot rapidly respond to drug-resistant viruses. Therefore, new anti-influenza virus strategies are required. Naringenin is a flavonoid with potential for new antiviral strategies. In this study, we evaluated the antiviral effects of naringenin derivatives and examined the relationship between their cellular uptake and antiviral effects. Madin-Darby canine kidney (MDCK) cells were infected with the A/PR/8/34 strain and exposed to the compound-containing medium for 24 h. The amount of virus in the supernatant was calculated using focus-forming reduction assay. Antiviral activity was evaluated using IC50 and CC50 values. Cells were exposed to a constant concentration of naringenin or prenylated naringenin, and intracellular uptake and distribution were evaluated using a fluorescence microscope. Prenylated naringenin showed strong anti-influenza virus effects, and the amount of intracellular uptake was revealed by the strong intracellular fluorescence. In addition, intracellular distribution differed depending on the position of the prenyl group. The steric factor of naringenin is deeply involved in influenza A virus activity, and prenyl groups are desirable. Furthermore, the prenyl group affects cellular affinity, and the uptake mechanism differs depending on its position. These results provide important information on antiviral strategies.

Antiviral Potential of Natural Resources against Influenza Virus Infections.

Influenza is a severe contagious disease caused by influenza A and B viruses. The WHO estimates that annual outbreaks lead to 3-5 million severe infections of which approximately 10% lead to the death of the patient. While vaccination is the cornerstone of prevention, antiviral drugs represent the most important treatment option of acute infections. Only two classes of drugs are currently approved for the treatment of influenza in numerous countries: M2 channel blockers and neuraminidase inhibitors. In some countries, additional compounds such as the recently developed cap-dependent endonuclease inhibitor baloxavir marboxil or the polymerase inhibitor favipiravir are available. However, many of these compounds suffer from poor efficacy, if not applied early after infection. Furthermore, many influenza strains have developed resistances and lost susceptibility to these compounds. As a result, there is an urgent need to develop new anti-influenza drugs against a broad spectrum of subtypes. Natural products have made an important contribution to the development of new lead structures, particularly in the field of infectious diseases. Therefore, this article aims to review the research on the identification of novel lead structures isolated from natural resources suitable to treat influenza infections.

Studying expression of IL-1β gene under the action of siRNA complexes with anti-influenza effect

Influenza is one of the most urgent global health problems today. The influenza virus has immunosuppressive properties, which can lead to the development of secondary immunodeficiencies, interfering with the functioning of the interferon system activation, thus leading to impaired production of pro-inflammatory cytokines. IL-1 is the most important player in development of antiviral immunity. This cytokine plays an important role in boosting the expression of the MCP-1 and MCP-3 genes and maturation of macrophages and dendritic cells. Induction of IL-1 production occurs due to interaction of the ligand with Toll-like receptors. Currently, there is a lot of drugs aimed at the prevention and treatment of influenza infection. However, their use in some cases is difficult due to high mutational variability of the influenza virus, thus making it resistant to these drugs. Therefore, the issue of developing and creating effective methods to combat such infections is of particular importance. A promising approach to the treatment and prevention of viral respiratory infections may be connected with RNA interference. This process consists of degradation of foreign mRNA by small interfering RNA (siRNA) molecules. The aim of the present study was to evaluate expression of the IL-1 gene upon transfection of miRNA complexes directed to the cellular FLT4, Nup98, Nup205 genes. Evaluation of changed viral reproduction was carried out using titration by CPE virus-containing fluid. Expression level of the IL-1 gene was determined by means of real-time RT-PCR. Assessment of the changes in viral reproduction allowed us to reveal that the use of all the miRNA complexes directed to the cellular genes lead to a significant decrease in viral reproduction on the 1st day after infection. Usage of Nup205 + FLT4 and FLT4 + Nup205 + Nup98 complexes proved to cause a decrease in viral reproduction on the second day as well (p 0.05), as compared with nonspecific and viral controls. When analyzing expression profile of the IL-1 gene, an increase in its expression was observed on the 1st day for all miRNA complexes and on the 2nd and 3rd days for the Nup98 + FLT4 and Nup205 + Nup98 complexes. In the course of the study, it was found that suppression of the cellular genes FLT4, Nup98 and Nup205 activities, which are necessary for viral reproduction, led to a significant decrease in viral activity and an increase in IL-1 expression.

Design, Synthesis, and Biological Activity of a Novel Series of 2-Ureidonicotinamide Derivatives Against Influenza A Virus.

Viral resistance to existing inhibitors and the time-dependent effectiveness of neuraminidase inhibitors have limited the number of antivirals that can be used for prophylaxis and therapeutic treatment of severe influenza infection. Thus, there is an urgent need to develop new drugs to prevent and treat influenza infection. The aims of this study was to design and synthesize a novel series of 2-ureidonicotinamide derivatives and evaluate their anti-IAV activities. Furthermore, we predicted the abilities of these compounds to inhibit the PA-PB1 subunit and forecasted the docking poses of these compounds with RNA polymerase protein (PDB ID 3CM8). The novel designed compounds were synthesized using classical methods of organic chemistry and tested in vitro for their abilities inhibiting RNP and against influenza A virus. In addition, the 23 synthesized molecules were subjected to the generated pharmacophore Hypo1 to forecast the activity target PA-PB1 subunit of RNA polymerase. The ADMET pharmacokinetic parameters were calculated by the ADMET modules in Discovery Studio 2016. The docking results helped us demonstrate the possible interactions between these compounds with 3CM8. The synthesized 2-ureidonicotinamide derivatives were characterized as potent anti-influenza inhibitors. The target compounds 7b and 7c demonstrated significant antiviral activities and could be considered as novel lead compounds of antiviral inhibitors. In addition, compound 7b revealed suitable ADME properties expressed and might be a significant RNA polymerase inhibitor targeting the PA-PB1 subunit based on the predictable results and the docking results. This study revealed a novel series of compounds that might be useful in the search for an effective drug against the influenza virus.

AG1478 Elicits a Novel Anti-Influenza Function via an EGFR-Independent, GBF1-Dependent Pathway.

Current options for preventing or treating influenza are still limited, and new treatments for influenza viral infection are urgently needed. In the present study, we serendipitously found that a small-molecule inhibitor (AG1478), previously used for epidermal growth factor receptor (EGFR) inhibition, demonstrated a potent activity against influenza both in vitro and in vivo. Surprisingly, the antiviral effect of AG1478 was not mediated by its EGFR inhibitory activity, as influenza virus was insensitive to EGFR blockade by other EGFR inhibitors or by siRNA knockdown of EGFR. Its antiviral activity was also interferon independent as demonstrated by a Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) knockout approach. Instead, AG1478 was found to target the Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1 (GBF1)–ADP-ribosylation factor 1 (ARF1) system by reversibly inhibiting GBF1 activity and disrupting its Golgi-cytoplasmic trafficking. Compared to known GBF1 inhibitors, AG1478 demonstrated lower cellular toxicity and better preservation of Golgi structure. Furthermore, GBF1 was found to interact with a specific set of viral proteins including M1, NP, and PA. Additionally, the alternation of GBF1 distribution induced by AG1478 treatment disrupted these interactions. Because targeting host factors, instead of the viral component, imposes a higher barrier for developing resistance, GBF1 modulation may be an effective approach to treat influenza infection.

Influenza: clinical aspects, diagnosis, and treatment.

To review the clinico-epidemiological aspects of influenza in the context of the Coronavirus Disease 2019 (COVID-19) pandemic; the recent advances in point-of-care molecular diagnostics and co-detection of influenza and coronaviruses, and the development of new influenza therapeutics. Rates of influenza have declined globally since the 2020-2021 season; waning population immunity and uncertainty in vaccine strains could pose a risk in its significant resurgence, especially where pandemic public health interventions start being lifted. As symptoms are similar for influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, accurate, rapid diagnostics are needed to guide management. In addition to neuraminidase inhibitors, newer class of antivirals including polymerase inhibitors show promise in treating influenza infections in adults, children, and high-risk individuals. This review summarizes the most recent data on rapid molecular diagnostics, including point-of-care tests and co-detection of influenza and SARS-CoV-2 viruses. The implications to inform clinical and infection control practices, and detection of antiviral resistance are discussed. The latest clinical trial data on neuraminidase inhibitors and polymerase inhibitors, their efficacy, limitations, and resistance concerns are reviewed.

Effectiveness of oseltamivir treatment on clinical failure in hospitalized patients with lower respiratory tract infection

BackgroundInfluenza is associated with excess morbidity and mortality of individuals each year. Few therapies exist for treatment of influenza infection, and each require initiation as early as possible in the course of infection, making efficacy difficult to estimate in the hospitalized patient with lower respiratory tract infection. Using causal machine learning methods, we re-analyze data from a randomized trial of oseltamivir versus standard of care aimed at reducing clinical failure in hospitalized patients with lower respiratory tract infection during the influenza season.MethodsThis was a secondary analysis of the Rapid Empiric Treatment with Oseltamivir Study (RETOS). Conditional average treatment effects (CATE) and 95% confidence intervals were computed from causal forest including 85 clinical and demographic variables. RETOS was a multicenter, randomized, unblinded, trial of adult patients hospitalized with lower respiratory tract infections in Kentucky from 2009 through 2012. Adult hospitalized patients with lower respiratory tract infection were randomized to standard of care or standard of care plus oseltamivir as early as possible after hospital admission but within 24 h of enrollment. After randomization, oseltamivir was initiated in the treatment arm per package insert. The primary outcome was clinical failure, a composite measure including failure to reach clinical improvement within 7 days, transfer to intensive care 24 h after admission, or rehospitalization or death within 30 days.ResultsA total of 691 hospitalized patients with lower respiratory tract infections were included in the study. The only subgroup of patients with a statistically significant CATE was those with laboratory-confirmed influenza infection with a 26% lower risk of clinical failure when treated with oseltamivir (95% CI 3.2–48.0%).ConclusionsThis study suggests that addition of oseltamivir to standard of care may decrease clinical failure in hospitalized patients with influenza-associated lower respiratory tract infection versus standard of care alone. These results are supportive of current recommendations to initiate antiviral treatment in hospitalized patients with confirmed or suspected influenza as soon as possible after admission.Trial registration Original trial: Clinical Trials.Gov; Rapid Empiric Treatment With Oseltamivir Study (RETOS) (RETOS); ClinicalTrials.gov Identifier: NCT01248715 https://clinicaltrials.gov/ct2/show/NCT01248715

Discovery and optimization of new 6, 7-dihydroxy-1, 2, 3, 4-tetrahydroisoquinoline derivatives as potent influenza virus PAN inhibitors

Annual unpredictable efficacy of vaccines, coupled with emerging drug resistance, underlines the development of new antiviral drugs to treat influenza infections. The N-terminal domain of the PA (PAN) endonuclease is both highly conserved across influenza strains and serotypes and is indispensable for the viral lifecycle, making it an attractive target for new antiviral therapies. Here, we describe the discovery of a new class of PAN inhibitors derived from recently identified, highly active hits for PAN endonuclease inhibition. By use of structure-guided design and systematic SAR exploration, the hits were elaborated through a fragment growing strategy, giving rise to a series of 1, 3-cis-2-substituted-1-(3, 4-dihydroxybenzyl)-6, 7-dihydroxy-1, 2, 3, 4-tetrahydroisoquinoline-3-carboxylic acid derivatives as potent PAN inhibitors. This approach ultimately resulted in the development of a new lead compound 13e, which exhibited an EC50 value of 4.50 μM against H1N1 influenza virus in MDCK cells.

Antiviral Activity of Chrysin against Influenza Virus Replication via Inhibition of Autophagy.

Influenza viruses cause respiratory infections in humans and animals, which have high morbidity and mortality rates. Although several drugs that inhibit viral neuraminidase are used to treat influenza infections, the emergence of resistant viruses necessitates the urgent development of new antiviral drugs. Chrysin (5,7-dihydroxyflavone) is a natural flavonoid that exhibits antiviral activity against enterovirus 71 (EV71) by inhibiting viral 3C protease activity. In this study, we evaluated the antiviral activity of chrysin against influenza A/Puerto Rico/8/34 (A/PR/8). Chrysin significantly inhibited A/PR/8-mediated cell death and the replication of A/PR/8 at concentrations up to 2 μM. Viral hemagglutinin expression was also markedly decreased by the chrysin treatment in A/PR/8-infected cells. Through the time course experiment and time-of-addition assay, we found that chrysin inhibited viral infection at the early stages of the replication cycle. Additionally, the nucleoprotein expression of A/PR/8 in A549 cells was reduced upon treatment with chrysin. Regarding the mechanism of action, we found that chrysin inhibited autophagy activation by increasing the phosphorylation of mammalian target of rapamycin (mTOR). We also confirmed a decrease in LC3B expression and LC3-positive puncta levels in A/PR/8-infected cells. These results suggest that chrysin exhibits antiviral activity by activating mTOR and inhibiting autophagy to inhibit the replication of A/PR/8 in the early stages of infection.

Investigation of genetic variation: Neuraminidase gene of influenza Avirus H1N1/pdm09, Shiraz, Iran (2015-2016).

Oseltamivir and antiviral agents are frequently used for the prevention and treatment of influenza infection. However, resistance to oseltamivir has been reported globally due to a mutation in the Influenza virus neuraminidase gene. Such resistance will be detected by genotyping and phenotyping studies of viral isolates. The recent study aimed to determine the genetic mutation of neuraminidase gene in influenza A (H1N1) viruses isolated from children referred to Shiraz tertiary hospitals during 1 year (2015-2016) with influenza-like symptoms. A total of 300 patients were registered and throat samples were taken. The throat swabs were used for viral RNA extraction. Detection of influenza A (H1N1) was performed using the one-step real-time polymerase chain reaction (qRT-PCR) method. From positive isolates for H1N1, 51 random samples were evaluated for neuraminidase gene mutation with the nested PCR-sequencing method. Of 300 cases, 102 (34%) isolates were detected as influenza A (H1N1) pdm09. Based on sequencing results, 2 of the 44 sequenced isolates exhibited H275Y substitution, which presented oseltamivir resistance. In comparison with reference strain, the phylogenetic analysis of sequenced isolates was classified in genogroup 6B. While this result is the first report of emerging oseltamivir-resistant in the southwest of Iran, it is highly recommended to perform these evaluations on the different geographical regions in any prevalence area to plan treatment strategies for influenza.

Impact of Oseltamivir Treatment on Influenza A and B Virus Dynamics in Human Volunteers.

Influenza viruses infect millions of humans every year causing an estimated 400,000 deaths globally. Due to continuous virus evolution current vaccines provide only limited protection against the flu. Several antiviral drugs are available to treat influenza infection, and one of the most commonly used drugs is oseltamivir (Tamiflu). While the mechanism of action of oseltamivir as a neuraminidase inhibitor is well-understood, the impact of oseltamivir on influenza virus dynamics in humans has been controversial. Many clinical trials with oseltamivir have been done by pharmaceutical companies such as Roche but the results of these trials until recently have been provided as summary reports or papers. Typically, such reports included median virus shedding curves for placebo and drug-treated influenza virus infected volunteers often indicating high efficacy of the early treatment. However, median shedding curves may be not accurately representing drug impact in individual volunteers. Importantly, due to public pressure clinical trials data testing oseltamivir efficacy has been recently released in the form of redacted PDF documents. We digitized and re-analyzed experimental data on influenza virus shedding in human volunteers from three previously published trials: on influenza A (1 trial) or B viruses (2 trials). Given that not all volunteers exposed to influenza viruses actually start virus shedding we found that impact of oseltamivir on the virus shedding dynamics was dependent on (i) selection of volunteers that were infected with the virus, and (ii) the detection limit in the measurement assay; both of these details were not well-articulated in the published studies. By assuming that any non-zero viral measurement is above the limit of detection we could match previously published data on median influenza A virus (flu A study) shedding but not on influenza B virus shedding (flu B study B) in human volunteers. Additional analyses confirmed that oseltamivir had an impact on the duration of shedding and overall shedding (defined as area under the curve) but this result varied by the trial. Interestingly, treatment had no impact on the rates at which shedding increased or declined with time in individual volunteers. Additional analyses showed that oseltamivir impacted the kinetics of the end of viral shedding, and in about 20–40% of volunteers that shed the virus treatment had no impact on viral shedding duration. Our results suggest an unusual impact of oseltamivir on influenza viruses shedding kinetics and caution about the use of published median data or data from a few individuals for inferences. Furthermore, we call for the need to publish raw data from critical clinical trials that can be independently analyzed.

Influenza virus infection increases ACE2 expression and shedding in human small airway epithelial cells.

BackgroundPatients with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demonstrate high rates of co-infection with respiratory viruses, including influenza A (IAV), suggesting pathogenic interactions.MethodsWe investigated how IAV may increase the risk of COVID-19 lung disease, focusing on the receptor angiotensin-converting enzyme (ACE)2 and the protease TMPRSS2, which cooperate in the intracellular uptake of SARS-CoV-2.ResultsWe found, using single-cell RNA sequencing of distal human nondiseased lung homogenates, that at baseline, ACE2 is minimally expressed in basal, goblet, ciliated and secretory epithelial cells populating small airways. We focused on human small airway epithelial cells (SAECs), central to the pathogenesis of lung injury following viral infections. Primary SAECs from nondiseased donor lungs apically infected (at the air-liquid interface) with IAV (up to 3×105 pfu; ~1 multiplicity of infection) markedly (eight-fold) boosted the expression of ACE2, paralleling that of STAT1, a transcription factor activated by viruses. IAV increased the apparent electrophoretic mobility of intracellular ACE2 and generated an ACE2 fragment (90 kDa) in apical secretions, suggesting cleavage of this receptor. In addition, IAV increased the expression of two proteases known to cleave ACE2, sheddase ADAM17 (TACE) and TMPRSS2 and increased the TMPRSS2 zymogen and its mature fragments, implicating proteolytic autoactivation.ConclusionThese results indicate that IAV amplifies the expression of molecules necessary for SARS-CoV-2 infection of the distal lung. Furthermore, post-translational changes in ACE2 by IAV may increase vulnerability to lung injury such as acute respiratory distress syndrome during viral co-infections. These findings support efforts in the prevention and treatment of influenza infections during the COVID-19 pandemic.

Recent progress in chemical approaches for the development of novel neuraminidase inhibitors.

Influenza virus is the main cause of an infectious disease called influenza affecting the respiratory system including the throat, nose and lungs. Neuraminidase inhibitors are reagents used to block the enzyme called neuraminidase to prevent the influenza infection from spreading. Neuraminidase inhibitors are widely used in the treatment of influenza infection, but still there is a need to develop more potent agents for the more effective treatment of influenza. Complications of the influenza disease lead to death, and one of these complications is drug resistance; hence, there is an urgent need to develop more effective agents. This review focuses on the recent advances in chemical synthesis pathways used for the development of new neuraminidase agents along with the medicinal aspects of chemically modified molecules, including the structure–activity relationship, which provides further rational designs of more active small molecules.

1276. Evaluation of CD377, a Novel Antiviral Fc-Conjugate (AVC), In Vitro Activity and In Vivo Efficacy in Immune-Competent and -Deficient (SCID) Lethal Mouse Models

BackgroundCidara’s AVCs are novel, potent, antiviral agents conjugated with the Fc domain of human IgG1. CD377 is an AVC development candidate being evaluated for prevention and treatment of seasonal and pandemic influenza, including in immune-deficient populations unable to benefit from vaccination. We evaluated CD377 in vitro and in SCID mice to determine the impact of compromised immune status on efficacy.MethodsCD377 and comparators (oseltamivir [OS], zanamivir [ZA], baloxavir marboxil [BM]) were evaluated in vitro by neuraminidase inhibition (NAI), and cytopathic effect (CPE) assays. The pharmacokinetics (PK) and efficacy of CD377 were determined in immune-competent (IC; BALB/c) and immune-deficient (ID; BALB/c SCID) mice. Efficacy was assessed by intranasal challenge at 3x the LD95 of influenza A/Puerto Rico/8/1934 (H1N1), followed by a single subcutaneous (SC) dose of CD377, 2 hours post-challenge. The SCID study also evaluated the efficacy of BM at 3 mg/kg (BID x 1 day). Body weights (BW) were monitored for 21 days, with 20% BW loss recorded as mortality.ResultsIn vitro evaluation by NAI showed CD377, OS, and ZA to be approximately equipotent, with IC50 values between 0.5 and 1.7 nM. However, by CPE, CD377 was ~4.5-fold more active than BM and >1,000-fold more active than OS and ZA.In vivo, the PK of CD377 was found to be comparable in IC and ID mice. In subsequent efficacy studies, CD377 was protective at 0.1 mg/kg in IC mice (P=0.0020 vs. vehicle), while control groups fully succumbed to infection by Day 7 (Fig. 1A).In a similar study with ID mice, CD377 dosed at 0.1 mg/kg was also fully protective (P=0.0020). In contrast, mice treated with 6 mg/kg (total dose) of BM were only partially protected until day 13 (40% mortality by study end) (Fig. 1B). The potency of CD377 was further supported by BW data, which mirrored the survival data in both studies.ConclusionCD377 exhibited potent in vitro activity and had similar PK in IC and ID mice. In efficacy studies, CD377 demonstrated robust potency in both IC and ID mouse models at equivalent doses (0.1 mg/kg, SC, single dose). These results support further development of CD377 as a novel antiviral for the prevention and treatment of influenza infection, including in people with immune deficiencies and higher risk of infection.Balb/c and Balb/c SCID DisclosuresJames Levin, PhD, Cidara Therapeutics (Shareholder) Karin Amundson, B.S., Cidara Therapeutics (Shareholder) Allen Borchardt, PhD, Cidara Therapeutics (Employee) Thanh Lam, PhD, Cidara Therapeutics (Shareholder) Tom Brady, PhD, Cidara Therapeutics (Shareholder) Elizabeth Abelovski, B.S., Cidara Therapeutics (Shareholder) Simon Döhrmann, PhD, Cidara Therapeutics (Shareholder) Jason Cole, PhD, Cidara Therapeutics (Shareholder) Voon Ong, PhD, Cidara Therapeutics, Inc. (Employee, Shareholder) Les Tari, PhD, Cidara Therapeutics (Shareholder)