Inhibition of influenza virus infection by a novel antiviral peptide that targets viral attachment to cells

Anti-HSV activity of nectin-1-derived peptides targeting HSV gD: an in-silico and in-vitro approach

Herpes simplex virus (HSV) infections affect a wide range of the global population. The emergence of resistance to the existing anti-HSV therapy highlights the necessity for an innovative strategy. The interaction of HSV gD with its main host receptor nectin-1 is a potential target for new antiviral drugs. The aim of this study was to develop a peptide derived from nectin-1 targeting HSV gD using the in-silico method and evaluate them for anti-HSV activity. Residues 59-133 of the Nectin-1 V-domain constitute the interaction interface with HSV gD. Bioinformatic tools viz., PEP-FOLD3, ClusPro 2.0, HawkDock and Desmond were used to model the peptide and confirm its binding specificity with HSV gD protein. The peptides with potential interactions were custom synthesized and anti-HSV activity was evaluated in vitro against HSV-1 and HSV-2 by CPE inhibition assay. Five peptide sequences were identified as exhibiting good interaction with HSV-gD proteins. Among them, peptide N1 (residues 76-90) offered maximum protection against HSV-1 (66.57%) and HSV-2 (71.12%) infections. Modification of the identified peptide through peptidomimetic approaches may further enhance the activity and stability of the identified peptide.Communicated by Ramaswamy H. Sarma.

Antiviral and anti-inflammatory activities of chemical constituents from twigs of Mosla chinensis Maxim

Seven undescribed compounds, including three flavones (1-3), one phenylpropanoid (19), three monoaromatic hydrocarbons (27-29), were isolated from the twigs of Mosla chinensis Maxim together with twenty-eight known compounds. The structures were characterized by HRESIMS, 1D and 2D NMR, and ECD spectroscopic techniques. Compound 20 displayed the most significant activity against A/WSN/33/2009 (H1N1) virus (IC50 = 20.47 μM) compared to the positive control oseltamivir (IC50 = 6.85 µM). Further research on the anti-influenza mechanism showed that compound 20 could bind to H1N1 virus surface antigen HA1 and inhibit the early attachment stage of the virus. Furthermore, compounds 9, 22, 23, and 25 displayed moderate inhibitory effects on the NO expression in LPS inducing Raw 264.7 cells with IC50 values of 22.78, 20.47, 27.66, and 30.14 µM, respectively.

Prediction of deleterious non-synonymous SNPs of TMPRSS2 protein combined with Molecular Dynamics Simulations and free energy analysis to identify the potential peptide substrates against SARS-CoV-2

Globally the SARS-CoV-2 viral infection demands for the new drugs, the TMPRSS2 target plays a vital role in facilitating the virus entry. The aim of the present study is to identify the potential peptide substrate from the Anti-viral database against TMPRSS2 of SARS-CoV-2. The compound screening and variation analysis were performed using molecular docking analysis and online tools such as PROVEAN and SNAP2 server, respectively. The re-docked crystal structure peptide substrate exhibits -128.151 kcal/mol whereas the RRKK peptide substrate shows -134.158 kcal/mol. Further, the selected compounds were proceeded with Molecular Dynamics Simulation, it explores the stability of the complex by revealing the hotspot residues (His296 and Ser441) were active for nucleophilic attack against TMPRSS2. The average Binding Free Energy values computed through MM/GBSA for RRKK, Camostat, and Crystal Structure were shown -69.9278 kcal/mol, -64.5983 kcal/mol, and -63.9755 kcal/mol, respectively against TMPRSS2. The 'rate of acylation' emerges as an indicator for RRKK's efficacy, it maintains the distance of 3.2 Å with Ser441 resembles, whilst its -NH backbone stabilizes at 2.5 Å 'Michaelis Complex' which leads to prevent the entry of SARS-CoV-2 to human cells. The sequence variation analysis explores that the V160 and G6 substitutions are essential to emphasize the uncover possibilities for the ongoing drug discovery research. Therefore, the identified peptide substrate found to be potent against SARS-CoV-2 and these results will be valuable for ongoing drug discovery research.Communicated by Ramaswamy H. Sarma.

The convergent evolution of influenza A virus: Implications, therapeutic strategies and what we need to know

Influenza virus infection, more commonly known as the 'cold flu', is an etiological agent that gives rise to recurrent annual flu and many pandemics. Dated back to the 1918- Spanish Flu, the influenza infection has caused the loss of many human lives and significantly impacted the economy and daily lives. Influenza virus can be classified into four different genera: influenza A-D, with the former two, influenza A and B, relevant to humans. The capacity of antigenic drift and shift in Influenza A has given rise to many novel variants, rendering vaccines and antiviral therapies useless. In light of the emergence of a novel betacoronavirus, the SARS-CoV-2, unravelling the underpinning mechanisms that support the recurrent influenza epidemics and pandemics is essential. Given the symptom similarities between influenza and covid infection, it is crucial to reiterate what we know about the influenza infection. This review aims to describe the origin and evolution of influenza infection. Apart from that, the risk factors entail the implication of co-infections, especially regarding the COVID-19 pandemic is further discussed. In addition, antiviral strategies, including the potential of drug repositioning, are discussed in this context. The diagnostic approach is also critically discussed in an effort to understand better and prepare for upcoming variants and potential influenza pandemics in the future. Lastly, this review encapsulates the challenges in curbing the influenza spread and provides insights for future directions in influenza management.

Computational peptide engineering approach for selection of the new C05 antibody-driven peptide with potency to blocking influenza a virus attachment; from in silico to in vivo

Antiviral drugs are currently used to prevent or treat viral infections like influenza A Virus (IAV). Nonetheless, annual genetic mutations of influenza viruses make them resistant to efficient treatment by current medications. Antiviral peptides have recently attracted researchers' attention and can potentially supplant the current medications. This study aimed to design peptides against IAV propagation. For this purpose, P2 and P3 peptides were computationally designed based on the HCDR3 region of the C05 antibody (a monoclonal antibody that neutralizes influenza HA protein and inhibits the virus attachment). The synthesized peptides were tested against the influenza A virus (A/Puerto Rico/8/34 (H1N1)) in vitro, and the most efficient peptide was selected for in vivo experiments. It was shown that the designed peptide shows much more prophylactic and therapeutic effects against the virus. These findings demonstrated that the designed peptide can control the virus infection without any cytotoxicity effect. Antiviral peptide design is acknowledged as a critical tactic to manage viral infections by preventing viral binding to the host cells.Communicated by Ramaswamy H. Sarma.

Potential cross-species transmission of highly pathogenic avian influenza H5 subtype (HPAI H5) viruses to humans calls for the development of H5-specific and universal influenza vaccines

In recent years, highly pathogenic avian influenza H5 subtype (HPAI H5) viruses have been prevalent around the world in both avian and mammalian species, causing serious economic losses to farmers. HPAI H5 infections of zoonotic origin also pose a threat to human health. Upon evaluating the global distribution of HPAI H5 viruses from 2019 to 2022, we found that the dominant strain of HPAI H5 rapidly changed from H5N8 to H5N1. A comparison of HA sequences from human- and avian-derived HPAI H5 viruses indicated high homology within the same subtype of viruses. Moreover, amino acid residues 137A, 192I, and 193R in the receptor-binding domain of HA1 were the key mutation sites for human infection in the current HPAI H5 subtype viruses. The recent rapid transmission of H5N1 HPAI in minks may result in the further evolution of the virus in mammals, thereby causing cross-species transmission to humans in the near future. This potential cross-species transmission calls for the development of an H5-specific influenza vaccine, as well as a universal influenza vaccine able to provide protection against a broad range of influenza strains.

Targeting Protein-Protein Interfaces with Peptides: The Contribution of Chemical Combinatorial Peptide Library Approaches

Protein-protein interfaces play fundamental roles in the molecular mechanisms underlying pathophysiological pathways and are important targets for the design of compounds of therapeutic interest. However, the identification of binding sites on protein surfaces and the development of modulators of protein-protein interactions still represent a major challenge due to their highly dynamic and extensive interfacial areas. Over the years, multiple strategies including structural, computational, and combinatorial approaches have been developed to characterize PPI and to date, several successful examples of small molecules, antibodies, peptides, and aptamers able to modulate these interfaces have been determined. Notably, peptides are a particularly useful tool for inhibiting PPIs due to their exquisite potency, specificity, and selectivity. Here, after an overview of PPIs and of the commonly used approaches to identify and characterize them, we describe and evaluate the impact of chemical peptide libraries in medicinal chemistry with a special focus on the results achieved through recent applications of this methodology. Finally, we also discuss the role that this methodology can have in the framework of the opportunities, and challenges that the application of new predictive approaches based on artificial intelligence is generating in structural biology.

Fighting the flu: a brief review on anti-influenza agents

The influenza virus causes one of the most prevalent and lethal infectious viral diseases of the respiratory system; the disease progression varies from acute self-limiting mild fever to disease chronicity and death. Although both the preventive and treatment measures have been vital in protecting humans against seasonal epidemics or sporadic pandemics, there are several challenges to curb the influenza virus such as limited or poor cross-protection against circulating virus strains, moderate protection in immune-compromised patients, and rapid emergence of resistance. Currently, there are four US-FDA-approved anti-influenza drugs to treat flu infection, viz. Rapivab, Relenza, Tamiflu, and Xofluza. These drugs are classified based on their mode of action against the viral replication cycle with the first three being Neuraminidase inhibitors, and the fourth one targeting the viral polymerase. The emergence of the drug-resistant strains of influenza, however, underscores the need for continuous innovation towards development and discovery of new anti-influenza agents with enhanced antiviral effects, greater safety, and improved tolerability. Here in this review, we highlighted commercially available antiviral agents besides those that are at different stages of development including under clinical trials, with a brief account of their antiviral mechanisms.

Bio-inspired synthesis of amino acids modified sulfated cellulose nanofibrils into multivalent viral inhibitors via the Mannich reaction

Virus cross-infection via surfaces poses a serious threat to public health. Inspired by natural sulfated polysaccharides and antiviral peptides, we prepared multivalent virus blocking nanomaterials by introducing amino acids to sulfated cellulose nanofibrils (SCNFs) via the Mannich reaction. The antiviral activity of the resulting amino acid-modified sulfated nanocellulose was significantly improved. Specifically, 1 h treatment with arginine modified SCNFs at a concentration of 0.1 g/mL led to a complete inactivation of the phage-X174 (reduction by more than three orders of magnitude). Atomic force microscope showed that amino acid-modified sulfated nanofibrils can bind phage-X174 to form linear clusters, thus preventing the virus from infecting the host. When we coated wrapping paper and the inside of a face-mask with our amino acid-modified SCNFs, phage-X174 was completely deactivated on the coated surfaces, demonstrating the potential of our approach for use in the packaging and personal protective equipment industries. This work provides an environmentally friendly and cost-efficient approach to fabricating multivalent nanomaterials for antiviral applications.

Designing Self-Inhibitory fusion peptide analogous to viral spike protein against novel severe acute respiratory syndrome (SARS-CoV-2)

COVID-19 is a highly contagious viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is declared pandemic by the World Health Organization (WHO). The spike protein of SARS-CoV-2 is a key component playing a pivotal role in facilitating viral fusion as well as release of genome into the host cell. Till date there is no clinically approved vaccine or drug available against Covid-19. We designed four hydrophobic inhibitory peptides (ITPs) based on WWIHS (Wimley and White interfacial hydrophobicity scale) score, targeting the HR1 domain of spike protein. Two inhibitory peptides out of four have a strong affinity to the hydrophobic surface of HR1 domain in pre-fusion spike protein. The MD simulation result showed the strong accommodation of ITPs with HR1 domain surface. These self-inhibitory peptides mimic the function of HR2 by binding to HR1 domain, thus inhibiting the formation of HR1-HR2 post-fusion complex, which is a key structure for virus-host tropism.Communicated by Ramaswamy H. Sarma.

Identification of multi-targeting natural antiviral peptides to impede SARS-CoV-2 infection

SARS-CoV-2 and its variants cause serious health concerns throughout the world. The alarming increase in the daily number of cases has become a nightmare in many low-income countries; although some vaccines are available, their high cost and low vaccine production make them unreachable to ordinary people in developing countries. Other treatment strategies are required for novel therapeutic options. The peptide-based drug is one of the alternatives with low toxicity, more specificity, and ease of synthesis. Herein, we have applied structure-based virtual screening to identify potential peptides targeting the critical proteins of SARS-CoV-2. Non-toxic natural antiviral peptides were selected from the enormous number of peptides. Comparative modeling was applied to prepare a 3D structure of selected peptides. 3D models of the peptides were docked using the ClusPro docking server to determine their binding affinity and peptide-protein interaction. The high-scoring peptides were docked with other crucial proteins to analyze multiple targeting peptides. The two best peptides were subjected to MD simulations to validate the structure stability and evaluated RMSD, RMSF, Rg, SASA, and H-bonding from the trajectory analysis of 100 ns. The proposed lead peptides can be used as a broad-spectrum drug and potentially develop as a therapeutic to combat SARS-CoV-2, positively impacting the current pandemic.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11224-022-02113-9.

Passive antifouling and active self-disinfecting antiviral surfaces

Viruses pose a serious threat to human health and society in general, as virus infections are one of the main causes of morbidity and mortality. Till May 2022, over 513 million people around the world have been confirmed to be infected and more than 6.2 million have died due to SARS-CoV-2. Although the COVID-19 pandemic will be defeated in the near future, we are likely to face new viral threats in the coming years. One of the important instruments to protect from viruses are antiviral surfaces, which are essentially capable of limiting their spread. The formulation of the concept of antiviral surfaces is relatively new. In general, five types of mechanism directed against virus spread can be proposed for antiviral surfaces; involving: direct and indirect actions, receptor inactivation, photothermal effect, and antifouling behavior. All antiviral surfaces can be classified into two main types - passive and active. Passive antiviral surfaces are based on superhydrophobic coatings that are able to repel virus contaminated droplets. In turn, viruses can become biologically inert (e.g., blocked or destroyed) upon contact with active antiviral surfaces, as they contain antiviral agents: metal atoms, synthetic or natural polymers, and small molecules. The functionality of antiviral surfaces can be significantly improved with additional properties, such as temperature- or pH-responsivity, multifunctionality, non-specific action on different virus types, long-term application, high antiviral efficiency and self-cleaning.

Antiviral Peptides as Anti-Influenza Agents

Influenza viruses represent a leading cause of high morbidity and mortality worldwide. Approaches for fighting flu are seasonal vaccines and some antiviral drugs. The development of the seasonal flu vaccine requires a great deal of effort, as careful studies are needed to select the strains to be included in each year's vaccine. Antiviral drugs available against Influenza virus infections have certain limitations due to the increased resistance rate and negative side effects. The highly mutative nature of these viruses leads to the emergence of new antigenic variants, against which the urgent development of new approaches for antiviral therapy is needed. Among these approaches, one of the emerging new fields of "peptide-based therapies" against Influenza viruses is being explored and looks promising. This review describes the recent findings on the antiviral activity, mechanism of action and therapeutic capability of antiviral peptides that bind HA, NA, PB1, and M2 as a means of countering Influenza virus infection.

Viral Aggregation: The Knowns and Unknowns

Viral aggregation is a complex and pervasive phenomenon affecting many viral families. An increasing number of studies have indicated that it can modulate critical parameters surrounding viral infections, and yet its role in viral infectivity, pathogenesis, and evolution is just beginning to be appreciated. Aggregation likely promotes viral infection by increasing the cellular multiplicity of infection (MOI), which can help overcome stochastic failures of viral infection and genetic defects and subsequently modulate their fitness, virulence, and host responses. Conversely, aggregation can limit the dispersal of viral particles and hinder the early stages of establishing a successful infection. The cost–benefit of viral aggregation seems to vary not only depending on the viral species and aggregating factors but also on the spatiotemporal context of the viral life cycle. Here, we review the knowns of viral aggregation by focusing on studies with direct observations of viral aggregation and mechanistic studies of the aggregation process. Next, we chart the unknowns and discuss the biological implications of viral aggregation in their infection cycle. We conclude with a perspective on harnessing the therapeutic potential of this phenomenon and highlight several challenging questions that warrant further research for this field to advance.

Inhibition of Viral Membrane Fusion by Peptides and Approaches to Peptide Design

Fusion of lipid-enveloped viruses with the cellular plasma membrane or the endosome membrane is mediated by viral envelope proteins that undergo large conformational changes following binding to receptors. The HIV-1 fusion protein gp41 undergoes a transition into a "six-helix bundle" after binding of the surface protein gp120 to the CD4 receptor and a co-receptor. Synthetic peptides that mimic part of this structure interfere with the formation of the helix structure and inhibit membrane fusion. This approach also works with the S spike protein of SARS-CoV-2. Here we review the peptide inhibitors of membrane fusion involved in infection by influenza virus, HIV-1, MERS and SARS coronaviruses, hepatitis viruses, paramyxoviruses, flaviviruses, herpesviruses and filoviruses. We also describe recent computational methods used for the identification of peptide sequences that can interact strongly with protein interfaces, with special emphasis on SARS-CoV-2, using the PePI-Covid19 database.

Potential of cell-penetrating peptides (CPPs) in delivery of antiviral therapeutics and vaccines

Viral infections are a great threat to human health. Currently, there are no effective vaccines and antiviral drugs against the majority of viral diseases, suggesting the need to develop novel and effective antiviral agents. Since the intracellular delivery of antiviral agents, particularly the impermeable molecules, such as peptides, proteins, and nucleic acids, are essential to exert their therapeutic effects, using a delivery system is highly required. Among various delivery systems, cell-penetrating peptides (CPPs), a group of short peptides with the unique ability of crossing cell membrane, offer great potential for the intracellular delivery of various biologically active cargoes. The results of numerous in vitro and in vivo studies with CPP conjugates demonstrate their promise as therapeutic agents in various medical fields including antiviral therapy. The CPP-mediated delivery of various antiviral agents including peptides, proteins, nucleic acids, and nanocarriers have been associated with therapeutic efficacy both in vitro and in vivo. This review describes various aspects of viruses including their biology, pathogenesis, and therapy and briefly discusses the concept of CPP and its potential in drug delivery. Particularly, it will highlight a variety of CPP applications in the management of viral infections.

Antiviral Activity of Peptide-Based Assemblies

The COVID-19 pandemic highlighted the importance of developing surfaces and coatings with antiviral activity. Here, we present, for the first time, peptide-based assemblies that can kill viruses. The minimal inhibitory concentration (MIC) of the assemblies is in the range tens of micrograms per milliliter. This value is 2 orders of magnitude smaller than the MIC of metal nanoparticles. When applied on a surface, by drop casting, the peptide spherical assemblies adhere to the surface and form an antiviral coating against both RNA- and DNA-based viruses including coronavirus. Our results show that the coating reduced the number of T4 bacteriophages (DNA-based virus) by 3 log, compared with an untreated surface and 6 log, when compared with a stock solution. Importantly, we showed that this coating completely inactivated canine coronavirus (RNA-based virus). This peptide-based coating can be useful wherever sterile surfaces are needed to reduce the risk of viral transmission.

Blocking HSV-1 glycoprotein K binding to signal peptide peptidase reduces virus infectivity in vitro and in vivo

HSV glycoprotein K (gK) is an essential herpes protein that contributes to enhancement of eye disease. We previously reported that gK binds to signal peptide peptidase (SPP) and that depletion of SPP reduces HSV-1 infectivity in vivo. To determine the therapeutic potential of blocking gK binding to SPP on virus infectivity and pathogenicity, we mapped the gK binding site for SPP to a 15mer peptide within the amino-terminus of gK. This 15mer peptide reduced infectivity of three different virus strains in vitro as determined by plaque assay, FACS, and RT-PCR. Similarly, the 15mer peptide reduced ocular virus replication in both BALB/c and C57BL/6 mice and also reduced levels of latency and exhaustion markers in infected mice when compared with control treated mice. Addition of the gK-15mer peptide also increased the survival of infected mice when compared with control mice. These results suggest that blocking gK binding to SPP using gK peptide may have therapeutic potential in treating HSV-1-associated infection.

Signal peptide peptidase (SPP) and HSV-1 glycoprotein K (gK) are essential genes in the host and virus, respectively. SPP and gK genes are both highly conserved. Previously we reported that gK binding to SPP is important for virus infectivity in vitro and in vivo. In this study we have identified the gK binding site to SPP and have shown that a gK peptide that blocks gK binding to SPP can block HSV-1 infectivity in vitro and in vivo using different strains of virus and mice. Thus, the ability of this peptide to block gK binding to SPP may be a useful tool to control HSV-1-induced eye disease in patients with herpes stromal keratitis (HSK).

Strategies to identify and develop antiviral peptides

The emergence and re-emergence of viral pathogens capable of causing epidemics or pandemics pose a serious healthcare burden. Small molecule antivirals used in conventional therapy have given rise to the severe problem of viral resistance against them. Peptides are generally considered safe, effective and are less likely to induce viral resistance. Antiviral peptides can be identified from screening of phage display of combinational peptide libraries, peptide array libraries or designed against viral targets. Limitations of peptides such as bioavailability can be improved with chemical modifications. Nanotechnology can further improve the stability of peptides in systemic circulation and enhance the antiviral activity of peptides, making them an appealing therapeutic option.

The Peptide TAT-I24 with Antiviral Activity against DNA Viruses Binds Double-Stranded DNA with High Affinity

The peptide TAT-I24, composed of the 9-mer peptide I24 and the TAT (48-60) peptide, exerts broad-spectrum antiviral activity against several DNA viruses. The current model of the mode of action suggests a reduction of viral entry and also a possible interaction with the viral DNA upon virus entry. To further support this model, the present study investigates the DNA binding properties of TAT-I24. DNA binding was analysed by gel retardation of a peptide-complexed DNA, fluorescence reduction of DNA labelled with intercalating dyes and determination of binding kinetics by surface plasmon resonance. Molecular dynamics simulations of DNA-peptide complexes predict high-affinity binding and destabilization of the DNA by TAT-I24. The effect on viral DNA levels of infected cells were studied by real-time PCR and staining of viral DNA by bromodeoxyuridine. TAT-I24 binds double-stranded DNA with high affinity, leading to inhibition of polymerase binding and thereby blocking of de novo nucleic acid synthesis. Analysis of early steps of virus entry using a bromodeoxyuridine-labelled virus as well as quantification of viral genomes in the cells indicate direct binding of the peptide to the viral DNA. Saturation of the peptide with exogenous DNA can fully neutralize the inhibitory effect. The antiviral activity of TAT-I24 is linked to its ability to bind DNA with high affinity. This mechanism could be the basis for the development of novel antiviral agents.

Identification of brevinin-1EMa-derived stapled peptides as broad-spectrum virus entry blockers

Based on the previously reported 13-residue antibacterial peptide analog, brevinin-1EMa (FLGWLFKVASKVL, peptide B), we attempted to design a novel class of antiviral peptides. For this goal, we synthesized three peptides with different stapling positions (B-2S, B-8S, and B-5S). The most active antiviral peptide with the specific stapling position (B-5S) was further modified in combination with either cysteine (B-5S3C, B-5S7C, and B-5S10C) or hydrophilic amino acid substitution (Bsub and Bsub-5S). Overall, B, B-5S, and Bsub-5S peptides showed superior antiviral activities against enveloped viruses such as retrovirus, lentivirus, hepatitis C virus, and herpes simplex virus with EC₅₀ values of 1-5 μM. Murine norovirus, a non-enveloped virus, was not susceptible to the virucidal actions of these peptides, suggesting the virus membrane disruption as their main antiviral mechanisms of action. We believe that these three novel peptides could serve as promising candidates for further development of membrane-targeting antiviral drugs in the future.

Tofacitinib downregulates antiviral immune defence in keratinocytes and reduces T cell activation

BACKGROUND

Tofacitinib is a novel Janus kinase (JAK) inhibitor approved for the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis. In clinical trials, the most common adverse events observed were nasopharyngitis, upper respiratory tract infections, and zoster. JAKs are found downstream of the type II cytokine receptor family used by a number of T_H17 cell-associated cytokines for signal transduction. These cytokines lead to the secretion of antiviral and antimicrobial peptides (AMPs) by keratinocytes or synoviocytes. Blocking the JAK pathway might result in a diminished secretion of antimicrobial and antiviral peptides causing higher susceptibility to infections in patients treated with JAK inhibitors.

METHODS

We treated primary human keratinocytes and synoviocytes with tofacitinib and subsequently added various cytokines and bacterial surface proteins before evaluation of the response via RT-qPCR. CD69 expression on tofacitinib-treated PBMCs was investigated via flow cytometry.

RESULTS

We found a markedly reduced gene expression of all tested antiviral peptides such as MX1 or ISG15 in keratinocytes and synoviocytes in the presence of tofacitinib in vitro. Additionally, we found that JAK inhibition reduced activation of T cells after stimulation with bacterial LPS or viral VZV gE.

CONCLUSIONS

The antiviral immunity is strongly inhibited in the presence of tofacitinib in vitro, while the antimicrobial immunity does not seem to be affected. In T cells, the overall activation process seems to be influenced by tofacitinib. These findings suggest that tofacitinib has an impact on antiviral immunity such as patients treated with tofacitinib often show adverse events like herpes zoster.

The Entry Blocker Peptide Produced in Chlamydomonas reinhardtii Inhibits Influenza Viral Replication in vitro

This year, a respiratory virus caused an emergency pandemic alert in health services around the world, showing the need for biotechnological approaches to fight these diseases. The influenza virus is one of the main viral agents that generate pandemic outbreaks. Currently, the majority of co-circulating influenza A virus (IAV) strains are adamantine- and oseltamivir-resistant strains, and the challenge is to find new antivirals for more efficient treatments. The antiviral entry blocker (EB) peptide is a promising candidate for blocking the virus entry into cells. The aim of this research was to express the EB peptide in the microalgae Chlamydomonas reinhardtii and test its antiviral activity against IAV in vitro. The EB peptide nucleotide sequence was introduced into the nuclear genome of microalgae using Agrobacterium tumefaciens transformation. The EB peptide amount produced in transformed microalgae was 4.99 ± 0.067% of the total soluble protein. In hemagglutination inhibition assays using influenza A/H1N1 pdm and influenza A H1N1/Virginia/ATCC/2009 strains, we reported that the EB peptide extract from the microalgae showed 100-fold higher efficiency than the EB synthetic peptide. In addition, both the EB peptide extract and synthetic peptide inhibited viral replication in MDCK cells (IC50 = 20.7 nM and IC50 = 754.4 nM, respectively); however, the EB peptide extract showed a 32-fold higher antiviral effectiveness than the synthetic peptide against influenza A/H1N1 pdm. Extracts from untransformed and transformed microalgae and synthetic peptide did not show cytotoxic effect on MDCK cell monolayers. Thus, C. reinhardtii may be a fast, safe, and effective expression platform for production of peptides with significant antiviral activity and can be used as a prophylactic treatment to reduce viral propagation.

Future antiviral polymers by plasma processing

Coronavirus disease 2019 (COVID-19) is largely threatening global public health, social stability, and economy. Efforts of the scientific community are turning to this global crisis and should present future preventative measures. With recent trends in polymer science that use plasma to activate and enhance the functionalities of polymer surfaces by surface etching, surface grafting, coating and activation combined with recent advances in understanding polymer-virus interactions at the nanoscale, it is promising to employ advanced plasma processing for smart antiviral applications. This trend article highlights the innovative and emerging directions and approaches in plasma-based surface engineering to create antiviral polymers. After introducing the unique features of plasma processing of polymers, novel plasma strategies that can be applied to engineer polymers with antiviral properties are presented and critically evaluated. The challenges and future perspectives of exploiting the unique plasma-specific effects to engineer smart polymers with virus-capture, virus-detection, virus-repelling, and/or virus-inactivation functionalities for biomedical applications are analysed and discussed.

Antiviral peptides against Enterovirus A71 causing hand, foot and mouth disease

The emergence of new and resistant viruses is a serious global burden. Conventional antiviral therapy with small molecules has led to the development of resistant mutants. In the case of hand, foot and mouth disease (HFMD), the absence of a US-FDA approved vaccine calls for urgent need to develop an antiviral that could serve as a safe, potent and robust therapy against the neurovirulent Enterovirus A71 (EV-A71). Natural peptides such as lactoferrin, melittin and synthetic peptides such as SP40, RGDS and LVLQTM have been studied against EV-A71 and have shown promising results as potent antivirals in pre-clinical studies. Peptides are considered safe, efficacious and pose fewer chances of resistance. Poor pharmacokinetic features of peptides can be overcome by the use of chemical modifications to improve in vivo delivery particularly by oral route. The use of nanotechnology can remarkably assist in the oral delivery of peptides and enhance stability in vivo. This can greatly increase patient compliance and make it more attractive as antiviral therapy.

Peptides and Dendrimers: How to Combat Viral and Bacterial Infections

The alarming growth of antimicrobial resistance and recent viral pandemic events have enhanced the need for novel approaches through innovative agents that are mainly able to attach to the external layers of bacteria and viruses, causing permanent damage. Antimicrobial molecules are potent broad-spectrum agents with a high potential as novel therapeutics. In this context, antimicrobial peptides, cell penetrating peptides, and antiviral peptides play a major role, and have been suggested as promising solutions. Furthermore, dendrimers are to be considered as suitable macromolecules for the development of advanced nanosystems that are able to complement the typical properties of dendrimers with those of peptides. This review focuses on the description of nanoplatforms constructed with peptides and dendrimers, and their applications.

Biomedical nanoparticle design: What we can learn from viruses

Viruses are nanomaterials with a number of properties that surpass those of many synthetic nanoparticles (NPs) for biomedical applications. They possess a rigorously ordered structure, come in a variety of shapes, and present unique surface elements, such as spikes. These attributes facilitate propitious biodistribution, the crossing of complex biological barriers and a minutely coordinated interaction with cells. Due to the orchestrated sequence of interactions of their stringently arranged particle corona with cellular surface receptors they effectively identify and infect their host cells with utmost specificity, while evading the immune system at the same time. Furthermore, their efficacy is enhanced by their response to stimuli and the ability to spread from cell to cell. Over the years, great efforts have been made to mimic distinct viral traits to improve biomedical nanomaterial performance. However, a closer look at the literature reveals that no comprehensive evaluation of the benefit of virus-mimetic material design on the targeting efficiency of nanomaterials exists. In this review we, therefore, elucidate the impact that viral properties had on fundamental advances in outfitting nanomaterials with the ability to interact specifically with their target cells. We give a comprehensive overview of the diverse design strategies and identify critical steps on the way to reducing them to practice. More so, we discuss the advantages and future perspectives of a virus-mimetic nanomaterial design and try to elucidate if viral mimicry holds the key for better NP targeting.

Peptides to combat viral infectious diseases

Viral infectious diseases have resulted in millions of deaths throughout history and have created a significant public healthcare burden. Tremendous efforts have been placed by the scientific communities, health officials and government organizations to detect, treat, and prevent viral infection. However, the complicated life cycle and rapid genetic mutations of viruses demand continuous development of novel medicines with high efficacy and safety profiles. Peptides provide a promising outlook as a tool to combat the spread and re-emergence of viral infection. This article provides an overview of five viral infectious diseases with high global prevalence: influenza, chronic hepatitis B, acquired immunodeficiency syndrome, severe acute respiratory syndrome, and coronavirus disease 2019. The current and potential peptide-based therapies, vaccines, and diagnostics for each disease are discussed.

Nanoparticles Mimicking Viral Cell Recognition Strategies Are Superior Transporters into Mesangial Cells

Poor drug availability in the tissue of interest is a frequent cause of therapy failure. While nanotechnology has developed a plethora of nanocarriers for drug transport, their ability to unequivocally identify cells of interest remains moderate. Viruses are the ideal nanosized carriers as they are able to address their embedded nucleic acids with high specificity to their host cells. Here, it is reported that particles endowed with a virus-like ability to identify cells by three consecutive checks have a superior ability to recognize mesangial cells (MCs) in vivo compared to conventional nanoparticles. Mimicking the initial viral attachment followed by a stepwise target cell recognition process leads to a 5- to 15-fold higher accumulation in the kidney mesangium and extensive cell uptake compared to particles lacking one or both of the viral traits. These results highlight the relevance that the viral cell identification process has on specificity and its application on the targeting strategies of nanomaterials. More so, these findings pave the way for transporting drugs into the mesangium, a tissue that is pivotal in the development of diabetic nephropathy and for which currently no efficient pharmacotherapy exists.

Obesity-Related Microenvironment Promotes Emergence of Virulent Influenza Virus Strains

Obesity is associated with increased disease severity, elevated viral titers in exhaled breath, and significantly prolonged viral shed during influenza A virus infection. Due to the mutable nature of RNA viruses, we questioned whether obesity could also influence influenza virus population diversity. Here, we show that minor variants rapidly emerge in obese mice. The variants exhibit increased viral replication, resulting in enhanced virulence in wild-type mice. The increased diversity of the viral population correlated with decreased type I interferon responses, and treatment of obese mice with recombinant interferon reduced viral diversity, suggesting that the delayed antiviral response exhibited in obesity permits the emergence of a more virulent influenza virus population. This is not unique to obese mice. Obesity-derived normal human bronchial epithelial (NHBE) cells also showed decreased interferon responses and increased viral replication, suggesting that viral diversity also was impacted in this increasing population.IMPORTANCE Currently, 50% of the adult population worldwide is overweight or obese. In these studies, we demonstrate that obesity not only enhances the severity of influenza infection but also impacts viral diversity. The altered microenvironment associated with obesity supports a more diverse viral quasispecies and affords the emergence of potentially pathogenic variants capable of inducing greater disease severity in lean hosts. This is likely due to the impaired interferon response, which is seen in both obese mice and obesity-derived human bronchial epithelial cells, suggesting that obesity, aside from its impact on influenza virus pathogenesis, permits the stochastic accumulation of potentially pathogenic viral variants, raising concerns about its public health impact as the prevalence of obesity continues to rise.

IgG Fc-binding motif-conjugated HIV-1 fusion inhibitor exhibits improved potency and in vivo half-life: Potential application in combination with broad neutralizing antibodies

The clinical application of conventional peptide drugs, such as the HIV-1 fusion inhibitor enfuvirtide, is limited by their short half-life in vivo. To overcome this limitation, we developed a new strategy to extend the in vivo half-life of a short HIV-1 fusion inhibitory peptide, CP24, by fusing it with the human IgG Fc-binding peptide (IBP). The newly engineered peptide IBP-CP24 exhibited potent and broad anti-HIV-1 activity with IC50 values ranging from 0.2 to 173.7 nM for inhibiting a broad spectrum of HIV-1 strains with different subtypes and tropisms, including those resistant to enfuvirtide. Most importantly, its half-life in the plasma of rhesus monkeys was 46.1 h, about 26- and 14-fold longer than that of CP24 (t1/2 = 1.7 h) and enfuvirtide (t1/2 = 3 h), respectively. IBP-CP24 intravenously administered in rhesus monkeys could not induce significant IBP-CP24-specific antibody response and it showed no obvious in vitro or in vivo toxicity. In the prophylactic study, humanized mice pretreated with IBP-CP24 were protected from HIV-1 infection. As a therapeutic treatment, coadministration of IBP-CP24 and normal human IgG to humanized mice with chronic HIV-1 infection resulted in a significant decrease of plasma viremia. Combining IBP-CP24 with a broad neutralizing antibody (bNAb) targeting CD4-binding site (CD4bs) in gp120 or a membrane proximal external region (MPER) in gp41 exhibited synergistic effect, resulting in significant dose-reduction of the bNAb and IBP-CP24. These results suggest that IBP-CP24 has the potential to be further developed as a new HIV-1 fusion inhibitor-based, long-acting anti-HIV drug that can be used alone or in combination with a bNAb for treatment and prevention of HIV-1 infection.

Envelope-deforming antiviral peptide derived from influenza virus M2 protein

Molecules interfering with lipid bilayer function exhibit strong antiviral activity against a broad range of enveloped viruses, with a lower risk of resistance development than that for viral protein-targeting drugs. Amphipathic peptides are rich sources of such membrane-interacting antivirals. Here, we report that influenza viruses were effectively inactivated by M2 AH, an amphipathic peptide derived from the M2 protein of the influenza virus. Although overall hydrophobicity (<H>) of M2 AH was not related to antiviral activity, modification of the hydrophobic moment (<μH>) of M2 AH dramatically altered the antiviral activity of this peptide. M2 MH, a derivative of M2 AH with a <μH> of 0.874, showed a half maximal inhibitory concentration (IC₅₀) of 53.3 nM against the A/PR/8/34 strain (H1N1), which is 16-times lower than that of M2 AH. The selectivity index (IC₅₀/CC₅₀), where CC₅₀ is the half maximal cytotoxic concentration, was 360 for M2 MH and 81 for M2 AH. Dynamic light scattering spectroscopy and electron microscopy revealed that M2 AH-derived peptides did not disrupt liposomes but altered the shape of viruses. This result suggests that the shape of virus envelope was closely related to its activity. Thus, we propose that deforming without rupturing the membranes may achieve a high selectivity index for peptide antivirals.

Molecular docking based design of Dengue NS5 methyltransferase inhibitors

Dengue is a viral infection caused by RNA infection of the family Flaviviridae and spread by the Aedes mosquitoes. Dengue NS5 methyltransferase is a known drug target for the disease. Therefore, it is of interest to design potential inhibitors for the target using molecular docking analysis. Our analysis shows the binding of compounds STOCK1N-98943, STOCK1N-98872, STOCK1N-98956, STOCK1N-98865, and STOCK1N-98950 with the protein drug target with optimal binding features for further in vitro and in vivo evaluations.

A scorpion venom peptide Ev37 restricts viral late entry by alkalizing acidic organelles

Viral infections still threaten human health all over the world, and many people die from viral diseases every year. However, there are no effective vaccines or drugs for preventing or managing most viral diseases. Thus, the discovery and development of broad-spectrum antiviral agents remain urgent. Here, we expressed and purified a venom peptide, Ev37, from the scorpion Euscorpiops validus in a prokaryotic system. We found that rEv37 can inhibit dengue virus type 2 (DENV-2), hepatitis C virus (HCV), Zika virus (ZIKV), and herpes simplex virus type 1 (HSV-1) infections in a dose-dependent manner at noncytotoxic concentrations, but that it has no effect on Sendai virus (SeV) and adenovirus (AdV) infections in vitro Furthermore, rEv37 alkalized acidic organelles to prevent low pH-dependent fusion of the viral membrane-endosomal membrane, which mainly blocks the release of the viral genome from the endosome to the cytoplasm and then restricts viral late entry. Taken together, our results indicate that the scorpion venom peptide Ev37 is a broad-spectrum antiviral agent with a specific molecular mechanism against viruses undergoing low pH-dependent fusion activation during entry into host cells. We conclude that Ev37 is a potential candidate for development as an antiviral drug.

Influenza Virus: A Master Tactician in Innate Immune Evasion and Novel Therapeutic Interventions

Influenza is a contagion that has plagued mankind for many decades, and continues to pose concerns every year, with millions of infections globally. The frequent mutations and recombination of the influenza A virus (IAV) cast a looming threat that antigenically novel strains/subtypes will rise with unpredictable pathogenicity and fear of it evolving into a pandemic strain. There have been four major influenza pandemics, since the beginning of twentieth century, with the great 1918 pandemic being the most severe, killing more than 50 million people worldwide. The mechanisms of IAV infection, host immune responses, and how viruses evade from such defensive responses at the molecular and structural levels have been greatly investigated in the past 30 years. While this has advanced our understanding of virus–host interactions and human immunology, and has led to the development of several antiviral drugs, they have minimal impact on the clinical outcomes of infection. The heavy use of these drugs has also imposed selective pressure on IAV to evolve and develop resistance. Vaccination remains the cornerstone of public health efforts to protect against influenza; however, rapid mass-production of sufficient vaccines is unlikely to occur immediately after the beginning of a pandemic. This, therefore, requires novel therapeutic strategies against this continually emerging infectious virus with higher specificity and cross-reactivity against multiple strains/subtypes of IAVs. This review discusses essential virulence factors of IAVs that determine sustainable human-to-human transmission, the mechanisms of viral hijacking of host cells and subversion of host innate immune responses, and novel therapeutic interventions that demonstrate promising antiviral properties against IAV. This hopefully will promote discussions and investigations on novel avenues of prevention and treatment strategies of influenza, that are effective and cross-protective against multiple strains/subtypes of IAV, in preparation for the advent of future IAVs and pandemics.

A Perfect Storm: Increased Colonization and Failure of Vaccination Leads to Severe Secondary Bacterial Infection in Influenza Virus-Infected Obese Mice

Obesity is a risk factor for developing severe disease following influenza virus infection; however, the comorbidity of obesity and secondary bacterial infection, a serious complication of influenza virus infections, is unknown. To fill this gap in knowledge, lean and obese C57BL/6 mice were infected with a nonlethal dose of influenza virus followed by a nonlethal dose of Streptococcus pneumoniae Strikingly, not only did significantly enhanced death occur in obese coinfected mice compared to lean controls, but also high mortality was seen irrespective of influenza virus strain, bacterial strain, or timing of coinfection. This result was unexpected, given that most influenza virus strains, especially seasonal human A and B viruses, are nonlethal in this model. Both viral and bacterial titers were increased in the upper respiratory tract and lungs of obese animals as early as days 1 and 2 post-bacterial infection, leading to a significant decrease in lung function. This increased bacterial load correlated with extensive cellular damage and upregulation of platelet-activating factor receptor, a host receptor central to pneumococcal invasion. Importantly, while vaccination of obese mice against either influenza virus or pneumococcus failed to confer protection, antibiotic treatment was able to resolve secondary bacterial infection-associated mortality. Overall, secondary bacterial pneumonia could be a widespread, unaddressed public health problem in an increasingly obese population.IMPORTANCE Worldwide obesity rates have continued to increase. Obesity is associated with increased severity of influenza virus infection; however, very little is known about respiratory coinfections in this expanding, high-risk population. Our studies utilized a coinfection model to show that obesity increases mortality from secondary bacterial infection following influenza virus challenge through a "perfect storm" of host factors that lead to excessive viral and bacterial outgrowth. In addition, we found that vaccination of obese mice against either virus or bacteria failed to confer protection against coinfection, but antibiotic treatment did alleviate mortality. Combined, these results represent an understudied and imminent public health concern in a weighty portion of the global population.

Inhibition of highly pathogenic avian influenza (HPAI) virus by a peptide derived from vFLIP through its direct destabilization of viruses

The antiviral activities of synthesized Kα2-helix peptide, which was derived from the viral FLICE-like inhibitor protein (vFLIP) of Kaposi's sarcoma-associated herpesvirus (KSHV), against influenza A virus (IAV) were investigated in vitro and in vivo, and mechanisms of action were suggested. In addition to the robust autophagy activity of the Kα2-helix peptide, the present study showed that treatment with the Kα2 peptide fused with the TAT peptide significantly inhibited IAV replication and transmission. Moreover, TAT-Kα2 peptide protected the mice, that were challenged with lethal doses of highly pathogenic influenza A H5N1 or H1N1 viruses. Mechanistically, we found that TAT-Kα2 peptide destabilized the viral membranes, depending on their lipid composition of the viral envelop. In addition to IAV, the Kα2 peptide inhibited infections with enveloped viruses, such as Vesicular Stomatitis Virus (VSV) and Respiratory Syncytial Virus (RSV), without cytotoxicity. These results suggest that TAT-Kα2 peptide is a potential antiviral agent for controlling emerging or re-emerging enveloped viruses, particularly diverse subtypes of IAVs.

Anti-influenza Activity of a Bacillus subtilis Probiotic Strain

Among Bacillus bacteria, B. subtilis is the species that produces the most antimicrobial compounds. In this study, we analyzed the activity of probiotic strain B. subtilis 3 against the influenza virus. The antiviral effect of this strain has been demonstrated in vitro and in vivo A new peptide, P18, produced by the probiotic strain was isolated, purified, chemically synthesized, and characterized. Cytotoxicity studies demonstrated no toxic effect of P18 on Madin-Darby canine kidney (MDCK) cells, even at the highest concentration tested (100 μg/ml). Complete inhibition of the influenza virus in vitro was observed at concentrations of 12.5 to 100 μg/ml. The protective effect of P18 in mice was comparable to that of oseltamivir phosphate (Tamiflu). Further study will assess the potential of peptide P18 as an antiviral compound and as a promising candidate for the development of new antiviral vaccines.

Multivalent Peptide-Nanoparticle Conjugates for Influenza-Virus Inhibition

To inhibit binding of the influenza A virus to the host cell glycocalyx, we generate multivalent peptide-polymer nanoparticles binding with nanomolar affinity to the virus via its spike protein hemagglutinin. The chosen dendritic polyglycerol scaffolds are highly biocompatible and well suited for a multivalent presentation. We could demonstrate in vitro that by increasing the size of the polymer scaffold and adjusting the peptide density, viral infection is drastically reduced. Such a peptide-polymer conjugate qualified also in an in vivo infection scenario. With this study we introduce the first non-carbohydrate-based, covalently linked, multivalent virus inhibitor in the nano- to picomolar range by ensuring low peptide-ligand density on a larger dendritic scaffold.

Progress of small molecular inhibitors in the development of anti-influenza virus agents

The influenza pandemic is a major threat to human health, and highly aggressive strains such as H1N1, H5N1 and H7N9 have emphasized the need for therapeutic strategies to combat these pathogens. Influenza anti-viral agents, especially active small molecular inhibitors play important roles in controlling pandemics while vaccines are developed. Currently, only a few drugs, which function as influenza neuraminidase (NA) inhibitors and M2 ion channel protein inhibitors, are approved in clinical. However, the acquired resistance against current anti-influenza drugs and the emerging mutations of influenza virus itself remain the major challenging unmet medical needs for influenza treatment. It is highly desirable to identify novel anti-influenza agents. This paper reviews the progress of small molecular inhibitors act as antiviral agents, which include hemagglutinin (HA) inhibitors, RNA-dependent RNA polymerase (RdRp) inhibitors, NA inhibitors and M2 ion channel protein inhibitors etc. Moreover, we also summarize new, recently reported potential targets and discuss strategies for the development of new anti-influenza virus drugs.

Swine Influenza Virus (H1N2) Characterization and Transmission in Ferrets, Chile

Phylogenetic analysis of the influenza hemagglutinin gene (HA) has suggested that commercial pigs in Chile harbor unique human seasonal H1-like influenza viruses, but further information, including characterization of these viruses, was unavailable. We isolated influenza virus (H1N2) from a swine in a backyard production farm in Central Chile and demonstrated that the HA gene was identical to that in a previous report. Its HA and neuraminidase genes were most similar to human H1 and N2 viruses from the early 1990s and internal segments were similar to influenza A(H1N1)pdm09 virus. The virus replicated efficiently in vitro and in vivo and transmitted in ferrets by respiratory droplet. Antigenically, it was distinct from other swine viruses. Hemagglutination inhibition analysis suggested that antibody titers to the swine Chilean H1N2 virus were decreased in persons born after 1990. Further studies are needed to characterize the potential risk to humans, as well as the ecology of influenza in swine in South America.

Influenza Virus Overcomes Cellular Blocks To Productively Replicate, Impacting Macrophage Function

Whether influenza virus replication in macrophages is productive or abortive has been a topic of debate. Utilizing a panel of 28 distinct human, avian, and swine influenza viruses, we found that only a small subset can overcome cellular blocks to productively replicate in murine and primary human macrophages. Murine macrophages have two cellular blocks. The first block is during viral entry, where virions with relatively acid-stable hemagglutinin (HA) proteins are rendered incapable of pH-induced triggering for membrane fusion, resulting in lysosomal degradation. The second block is downstream of viral replication but upstream of late protein synthesis. In contrast, primary human macrophages only have one cellular block that occurs after late protein synthesis. To determine the impact of abortive replication at different stages of the viral life cycle or productive replication on macrophage function, we assessed cytotoxicity, nitric oxide or reactive oxygen species production, and phagocytosis. Intriguingly, productive viral replication decreased phagocytosis of IgG-opsonized bioparticles and Fc receptor CD16 and CD32 surface levels, a function, to our knowledge, never before reported for an RNA virus. These data suggest that replication in macrophages affects cellular function and plays an important role in pathogenesis during infection in vivo IMPORTANCE: Macrophages are a critical first line of defense against respiratory pathogens. Thus, understanding how viruses evade or exploit macrophage function will provide greater insight into viral pathogenicity and antiviral responses. We previously showed that only a subset of highly pathogenic avian (HPAI) H5N1 influenza virus strains could productively replicate in murine macrophages through a hemagglutinin (HA)-mediated mechanism. These studies expand upon this work and demonstrate that productive replication is not specific to unique HPAI H5N1 viruses; an H1N1 strain (A/WSN/33) can also replicate in macrophages. Importantly, we identify two cellular blocks limiting replication that can be overcome by an avian-like pH of activation for nuclear entry and a yet-to-be-identified mechanism(s) to overcome a postnuclear entry block. Overcoming these blocks reduces the cell's ability to phagocytose IgG-opsonized bioparticles by decreasing Fc receptor surface levels, a mechanism previously thought to occur during bacterial and DNA viral infections.

Novel magnetic relaxation nanosensors: an unparalleled "spin" on influenza diagnosis

Rapid detection and diagnosis of pathogenic strains of influenza is necessary for expedited treatment and quicker resolutions to the ever-rising flu pandemics. Considering this, we propose the development of novel magnetic relaxation nanosensors (MRnS) for the rapid detection of influenza through targeted binding with hemagglutinin. 2,6- and 2,3-sialic acid ligands and entry blocker peptides are conjugated to iron oxide nanoparticles to create functional MRnS. Positive detection of various hemagglutinin variants (H1 and H5) is possible with protein concentrations as little as 1.0 nM. Most importantly, detection using functional MRnS is achieved within minutes and differentiates between influenza subtypes. This specificity allows mixtures of MRnS to screen for multiple pathogens at once, discarding the need to conduct multiple individual tests. Current methods used to diagnose influenza, such as RT-PCR and viral culturing, while largely effective, are complex, time-consuming and costly. As well, they are not as sensitive or specific, and have been known to produce false-positive results. In contrast to these methods, targeted MRnS are robust, point-of-care diagnostic tools featuring simple, rapid and low-cost procedures. These qualities, as well as high sensitivity and specificity, and low turnaround times, make a strong case for the diagnostic application of MRnS in clinical settings.

Obesity Outweighs Protection Conferred by Adjuvanted Influenza Vaccination

Obesity is a risk factor for developing severe influenza virus infection, making vaccination of utmost importance for this high-risk population. However, vaccinated obese animals and adults have decreased neutralizing antibody responses. In these studies, we tested the hypothesis that the addition of either alum or a squalene-based adjuvant (AS03) to an influenza vaccine would improve neutralizing antibody responses and protect obese mice from challenge. Our studies demonstrate that adjuvanted vaccine does increase both neutralizing and nonneutralizing antibody levels compared to vaccine alone. Although obese mice mount significantly decreased virus-specific antibody responses, both the breadth and the magnitude of the responses against hemagglutinin (HA) and neuraminidase (NA) are decreased compared to the responses in lean mice. Importantly, even with a greater than fourfold increase in neutralizing antibody levels, obese mice are not protected against influenza virus challenge and viral loads remain elevated in the respiratory tract. Increasing the antigen dose affords no added protection, and a decreasing viral dose did not fully mitigate the increased mortality seen in obese mice. Overall, these studies highlight that, while the use of an adjuvant does improve seroconversion, vaccination does not fully protect obese mice from influenza virus challenge, possibly due to the increased sensitivity of obese animals to infection. Given the continued increase in the global obesity epidemic, our findings have important implications for public health.

Vaccination is the most effective strategy for preventing influenza virus infection and is a key component for pandemic preparedness. However, vaccines may fail to provide optimal protection in high-risk groups, including overweight and obese individuals. Given the worldwide obesity epidemic, it is imperative that we understand and improve vaccine efficacy. No work to date has investigated whether adjuvants increase the protective capacity of influenza vaccines in the obese host. In these studies, we show that adjuvants increased the neutralizing and nonneutralizing antibody responses during vaccination of lean and obese mice to levels considered “protective,” and yet, obese mice still succumbed to infection. This vulnerability is likely due to a combination of factors, including the increased susceptibility of obese animals to develop severe and even lethal disease when infected with very low viral titers. Our studies highlight the critical public health need to translate these findings and better understand vaccination in this increasing population.

Chemical Synthesis and In Vitro Evaluation of a Phage Display-Derived Peptide Active against Infectious Salmon Anemia Virus

Infectious salmon anemia virus (ISAV) is the etiological agent of the disease by the same name and causes major losses in the salmon industry worldwide. Epizootic ISAV outbreaks have occurred in Norway and, to a lesser degree, in Canada. In 2007, an ISAV outbreak in Chile destroyed most of the seasonal production and endangered the entire Chilean salmon industry. None of the existing prophylactic approaches have demonstrated efficacy in providing absolute protection from or even a palliative effect on ISAV proliferation. Sanitary control measures for ISAV, based on molecular epidemiology data, have proven insufficient, mainly due to high salmon culture densities and a constant presence of a nonpathogenic strain of the virus. This report describes an alternative treatment approach based on interfering peptides selected from a phage display library. The screening of a phage display heptapeptide library resulted in the selection of a novel peptide with significant in vitro antiviral activity against ISAV. This peptide specifically interacted with the viral hemagglutinin-esterase protein, thereby impairing virus binding, with plaque reduction assays showing a significant reduction in viral yields. The identified peptide acts at micromolar concentrations against at least two different pathogenic strains of the virus, without detectable cytotoxic effects on the tested fish cells. Therefore, antiviral peptides represent a novel alternative for controlling ISAV and, potentially, other fish pathogens.

IMPORTANCE

Identifying novel methods for the efficient control of infectious diseases is imperative for the future of global aquaculture. The present study used a phage display heptapeptide library to identify a peptide with interfering activity against a key protein of the infectious salmon anemia virus (ISAV). A piscine orthomyxovirus, ISAV is a continuous threat to the commercial sustainability of cultured salmon production worldwide. The complex epidemiological strategy of this pathogen has made prophylactic control extremely difficult. The identified antiviral peptide efficiently impairs ISAV infection in vitro by specifically blocking hemagglutinin-esterase, a pivotal surface protein of this virus. Peptide synthesis could further modify the primary structure of the identified peptide to improve specific activity and stability. The present results form the foundation for developing a new pharmacological treatment against ISAV.