Amantadine-resistance among H5N1 avian influenza viruses isolated in Northern China

Antiviral drugs in animal-derived matrices: A review

The ban of antiviral drugs in food-producing animals in several parts of the world, latest by Commission Delegated Regulation (EU) 2022/1644, has increased the need for food control laboratories to develop analytical methods and perform official controls. However, little is known about antiviral drugs, their use, and its analysis in food-producing animals in the EU. This review aims to provide insights into relevant viruses, antiviral drugs, and animal-derived matrices for analytical method development and monitoring purposes to implement in food control laboratories. For years, animal viruses, such as African swine fever and avian influenza, have caused many outbreaks. Besides, they led to large economic losses due to the applied control measures and a lack of available treatments. Considering these losses and the known effectiveness of authorized human antiviral drugs in different organisms, medicines such as amantadine in Chinese poultry have been misused. Various analytical methods, including screening assays and sensors (published 2016-2023), and mass spectrometry methods (published 2012-2023) have been outlined in this review for the monitoring of antiviral drugs in animal-derived matrices. However, pharmacokinetics information on metabolite formation and distribution of these substances in different animal-derived matrices is incomplete. Additionally, apart from a few countries, there is a lack of available data on the potential misuse of different antiviral drugs in animal-derived matrices. Although a handful of important antiviral drugs, such as influenza, broad-spectrum, antiretroviral, and herpes drugs, and animal-derived matrices, such as chicken muscle, are identified, the priority of the scope should be further specified by closing the aforementioned gaps.

Swine Influenza Viruses Isolated from 2019 to 2022 in Shandong Province, China, Exemplify the Dominant Genotype

Swine influenza viruses (SIVs) have been circulating in swine globally and are potential threats to human health. During the surveillance of SIVs in Shandong Province, China, from 2019 to 2022, 21 reassortant G4 genotype Eurasian avian-like (EA) H1N1 subtypes containing genes from the EA H1N1 (HA and NA), 2009 pandemic (pdm/09) H1N1 virus (PB2, PB1, PA, NP, and M), and classical swine (CS) H1N1 (NS) lineages were isolated. The analysis of the key functional amino acid sites in the isolated viruses showed that two mutation sites (190D and 225E) that preferentially bind to the human α2-6 sialic acid receptor were found in HA. In PB2, three mutation sites (271A, 590S, and 591R) that may increase mammalian fitness and a mutation site (431M) that increases pathogenicity in mice were found. A typical human signature marker that may promote infection in humans, 357K, was found in NP. The viruses could replicate efficiently in mouse lungs and turbinates, and one of the H1N1 isolates could replicate in mouse kidneys and brains without prior adaption, which indicates that the viruses potentially pose a threat to human health. Histopathological results showed that the isolated viruses caused typical bronchopneumonia and encephalitis in mice. The results indicate that G4 genotype H1N1 has potential transmissibility to humans, and surveillance should be enhanced, which could provide important information for assessing the pandemic potential of the viruses.

High pathogenic avian influenza A(H5) viruses of clade 2.3.4.4b in Europe-Why trends of virus evolution are more difficult to predict

Since 2016, A(H5Nx) high pathogenic avian influenza (HPAI) virus of clade 2.3.4.4b has become one of the most serious global threats not only to wild and domestic birds, but also to public health. In recent years, important changes in the ecology, epidemiology, and evolution of this virus have been reported, with an unprecedented global diffusion and variety of affected birds and mammalian species. After the two consecutive and devastating epidemic waves in Europe in 2020-2021 and 2021-2022, with the second one recognized as one of the largest epidemics recorded so far, this clade has begun to circulate endemically in European wild bird populations. This study used the complete genomes of 1,956 European HPAI A(H5Nx) viruses to investigate the virus evolution during this varying epidemiological outline. We investigated the spatiotemporal patterns of A(H5Nx) virus diffusion to/from and within Europe during the 2020-2021 and 2021-2022 epidemic waves, providing evidence of ongoing changes in transmission dynamics and disease epidemiology. We demonstrated the high genetic diversity of the circulating viruses, which have undergone frequent reassortment events, providing for the first time a complete overview and a proposed nomenclature of the multiple genotypes circulating in Europe in 2020-2022. We described the emergence of a new genotype with gull adapted genes, which offered the virus the opportunity to occupy new ecological niches, driving the disease endemicity in the European wild bird population. The high propensity of the virus for reassortment, its jumps to a progressively wider number of host species, including mammals, and the rapid acquisition of adaptive mutations make the trend of virus evolution and spread difficult to predict in this unfailing evolving scenario.

Highly pathogenic avian influenza A(H5N1) virus infection in farmed minks, Spain, October 2022

In October 2022, an outbreak in Europe of highly pathogenic avian influenza (HPAI) A(H5N1) in intensively farmed minks occurred in northwest Spain. A single mink farm hosting more than 50,000 minks was involved. The identified viruses belong to clade 2.3.4.4b, which is responsible of the ongoing epizootic in Europe. An uncommon mutation (T271A) in the PB2 gene with potential public health implications was found. Our investigations indicate onward mink transmission of the virus may have occurred in the affected farm.

Discovery and Optimization of an Aptamer and Its Sensing Ability to Amantadine Based on SERS via Binary Metal Nanoparticles

With the growing concern of illegal abuse of amantadine (AMD) and its potential harmful impact on humans, detection of AMD has become an urgent food safety and environmental topic. Biosensing is a promising method for this, but the effective recognition of AMD still remains a challenge. Herein, we isolated an aptamer (Am-20) for AMD through a 14-round iterative selection based on capture-SELEX. The preliminary interaction mechanism between AMD and Am-20 was clarified with the help of docking simulations. Facilitated by a base mutation and truncation strategy, an optimized aptamer Am-20-1 with a short length of 62-mer was obtained, which exhibited competitive affinity with a K_d value of 33.90 ± 5.16 nM. A structure-switching SERS-based aptasensor based on Am-20-1 was then established for AMD quantification via a binary metal nanoparticle-embedded Raman reporter substrate (AuNRs@ATP@AgNPs). The fabricated strategy showed a wide linear range (0.005∼25 ng/mL) and a low limit of detection (0.001 ng/mL) for AMD determination. We envision that the novel aptamer identified in this study will provide a complementary tool for specific recognition and detection of AMD and could assist in the supervision of illegal abuse of AMD.

Phylogenetic Inference of the 2022 Highly Pathogenic H7N3 Avian Influenza Outbreak in Northern Mexico

The Mexican lineage H7N3 highly pathogenic avian influenza virus (HPAIV) has persisted in Mexican poultry since its first isolation in 2012. To date, the detection of this virus has gradually expanded from the initial one state to 18 states in Mexico. Despite the HPAIV H7N3 outbreak occurring yearly, the transmission pathways have never been studied, disallowing the establishment of effective control measures. We used a phylogenetic approach to unravel the transmission pathways of 2022 H7N3 HPAIVs in the new outbreak areas in Northern Mexico. We present genetic data of H7N3 viruses produced from 18 poultry farms infected in the spring of 2022. Our results indicate that the virus responsible for the current outbreak in Northern Mexico evolved from the Mexican lineage H7N3 HPAIV discovered in 2012. In the current outbreak, we identified five clusters of infection with four noticeably different genetic backgrounds. It is a cluster IV-like virus that was transmitted into one northern state causing an outbreak, then spreading to another neighboring northern state, possibly via a human-mediated mechanical transmission mechanism. The long-distance transmission event highlights the necessity for the more rigorous enforcement of biosafety measures in outbreaks. Additionally, we examined the evolutionary processes shaping the viral genetic and antigenic diversities. It is imperative to enhance active surveillance to include birds, the environment, and humans to detect HPAI in domestic poultry at an earlier point and eliminate it.

Comparison of two fluorescence quantitative immunochromatographic assays for the detection of amantadine in chicken muscle

The two sensitive fluorescence quantitative immunochromatographic assays (FQICAs), background fluorescence quenching immunochromatographic assay (bFQICA) and time-resolved fluorescent immunochromatographic assay (TRFICA), play an important role increasingly in rapid detection technology for food safety. Amantadine (AMD), used extensively in virus infections in livestock and poultry, has been prohibited due to hazard concerns over public human health. Therefore, AMD was used as a model molecule in the FQICAs establishment and comparison based on the same bioreagents. The outstanding performance in technical parameters of the two FQICAs indicated that they could provide rapid, precise, reliable technical support for large-scale on-site screening for AMD detection. What's more, the systematic and comprehensive comparison of the two FQICAs would give useful suggestions for scientists and users in monitoring the harmful compounds.

Abuse of Amantadine in Poultry May Be Associated with Higher Fatality Rate of H5N1 Infections in Humans

Amantadine, an anti-viral drug, has been widely used in human anti-influenza treatments. However, several highly-pathogenic avian influenza viruses show amantadine-resistance mutations in the viral matrix 2 (M2) protein. Here we analyzed global H5N1 sequencing data and calculate possible correlations between frequencies of key mutations in M2 and the mortality rates. We found that frequency of L26I/V27A mutation in M2 (isolated from both human and avian hosts) is linearly correlated with the mortality rates of human H5N1 infections. The significant correlation between M2 mutations in avians and the mortality rates in humans suggest that the pre-existence of L26I/V27A in birds may determine patient fatalities after trans-infections from avian to human hosts. 100% prevalence of L26I/V27A mutation increased the mortality rates from 51% (95% CI 37%-65%) to 89% (95% CI 88%-90%). Mutations involving Leu26 or Val27 were identified to be the major mutations emerging from drug selection pressure. Thus the emergence of the super H5N1 virus with a fatality over 90% may be attributed to the abuse of amantadine in poultry, especially in some southeast Asian countries. A more stringent control to anti-viral veterinary drugs is imperative. This article is protected by copyright. All rights reserved.

Improving siRNA design targeting nucleoprotein gene as antiviral against the Indonesian H5N1 virus

Background

Small interfering RNA technology has been considered a prospective alternative antiviral treatment using gene silencing against influenza viruses with high mutations rates. On the other hand, there are no reports on its effectiveness against the highly pathogenic avian influenza H5N1 virus isolated from Indonesia.

Objectives

The main objective of this study was to improve the siRNA design based on the nucleoprotein gene (siRNA-NP) for the Indonesian H5N1 virus.

Methods

The effectiveness of these siRNA-NPs (NP672, NP1433, and NP1469) was analyzed in vitro in Marbin-Darby canine kidney cells.

Results

The siRNA-NP672 caused the largest decrease in viral production and gene expression at 24, 48, and 72 h post-infection compared to the other siRNA-NPs. Moreover, three serial passages of the H5N1 virus in the presence of siRNA-NP672 did not induce any mutations within the nucleoprotein gene.

Conclusions

These findings suggest that siRNA-NP672 can provide better protection against the Indonesian strain of the H5N1 virus.

Development and validation of a quantitative method for 15 antiviral drugs in poultry muscle using liquid chromatography coupled to tandem mass spectrometry

The objective of this work was to develop a quantitative multi-residue method for analysing antiviral drug residues and their metabolites in poultry meat samples. Antiviral drugs are not licensed for the treatment of influenza in food producing animals. However, there have been some reports indicating their illegal use in poultry. In this study, a method was developed for the analysis of 15 antiviral drug residues in poultry muscle (chicken, duck, quail and turkey) using liquid chromatography coupled to tandem mass spectrometry. This included 13 drugs against influenza and associated metabolites, but also two drugs employed for the treatment of herpes (acyclovir and ganciclovir). The method required the development of a novel chromatographic separation using a hydrophilic interaction chromatographic (HILIC) BEH amide column, which was necessary to retain the highly polar compounds. The analytes were detected using a triple quadrupole mass spectrometer operating in positive electrospray ionization mode. A range of different sample preparation protocols suitable for polar compounds were evaluated. The most effective procedure was based on a simple acetonitrile-based protein precipitation step followed by a further dilution in a methanol/water solution. The confirmatory method was validated according to the EU 2021/808 guidelines on different species including chicken, duck, turkey and quail. The validation was performed using various calibration curves ranging from 0.1 µg kg^-1to 200 µg kg^-1, according to the analyte. Depending on the analyte sensitivity, decision limits achieved ranged from 0.12 µg kg^-1 for arbidol to 34.7 µg kg^-1 for ribavirin. Overall, the reproducibility precision values ranged from 2.8% to 22.7% and the recoveries from 84% to 127%. The method was applied to 120 commercial poultry samples from the Irish market, which were all found to be residue-free.

Synthesis and characterization of tracers and development of a fluorescence polarization immunoassay for amantadine with high sensitivity in chicken

Fluorescence polarization immunoassay (FPIA) is a homogeneous and rapid analytical method that is suitable for high-throughput screening of large numbers of samples. However, FPIA typically suffers from lower sensitivity than the well-established enzyme-linked immunosorbent assay (ELISA), limiting its wide application as an analytical tool that can be run with trace levels of an analyte. Herein, a highly sensitive FPIA for detecting amantadine (AMD) in chicken is described. To achieve high sensitivity, nine chemical tracers of AMD that employ different fluoresceins, fluorescein derivatives, and haptens were synthesized and paired with four previously produced monoclonal antibodies (mAbs). The effect of the tracer structure on the sensitivity of FPIA was investigated and discussed. We found that the tracers with a linear and shorter bridge between adamantane and fluorescein generally provided higher sensitivity. After optimization, N'-(1-adamantyl) ethylenediamine (AEDA), an AMD structural analogue labeled with fluorescein isothiocyanate (FITC), achieved the lowest IC₅₀ value (1.0 ng/ml) in the FPIA, which was comparable to that of the heterologous ELISA format that used the same mAb7G2. We also investigated the possible recognition mechanism of mAbs in terms of conformational and electronic aspects. The developed FPIA was applied to chicken to detect AMD residue, demonstrating a limit of detection (LOD) of 0.9 µg/kg with recoveries of 76.5-89.3% and coefficients of variation (CVs) below 14.5%. These results show that the proposed FPIA is an efficient, accurate, and convenient method for the rapid screening of AMD residues in chicken. PRACTICAL APPLICATION: The fluorescence polarization immunoassay (FPIA) was developed to determine and quantify amantadine (AMD) in chicken samples with high sensitivity. This homogeneous method avoids coating and washing steps and may provide high-throughput AMD screening in chicken in 10 min with high accuracy and precision. FPIA can be used as a monitoring tool and contribute significantly to the rapid detection of AMD in chicken.

Distribution and evolution of H1N1 influenza A viruses with adamantanes-resistant mutations worldwide from 1918 to 2019

H1N1 influenza is a kind of acute respiratory infectious disease that has a high socioeconomic and medical burden each year around the world. In the past decades, H1N1 influenza viruses have exhibited high resistance to adamantanes, which has become a serious issue. To understand the up-to-date distribution and evolution of H1N1 influenza viruses with adamantanes-resistant mutations, we conducted a deep analysis of 15875 M2 protein and 8351 MP nucleotides sequences. Results of the distribution analyses showed that 77.32% of H1N1 influenza viruses harbored-resistance mutations of which 73.52% were S31N, And the mutant variants mainly appeared in North America and Europe and H1N1 influenza viruses with S31N mutation became the circulating strains since 2009 all over the world. In addition, 80.65% of human H1N1 influenza viruses and 74.61% of swine H1N1 influenza viruses exhibited adamantanes resistance, while the frequency was only 1.86% in avian H1N1 influenza viruses. Studies from evolutionary analyses indicated that the avian-origin swine H1N1 influenza viruses replaced the classical human H1N1 influenza viruses and became the circulating strains after 2009; The interspecies transmission among avian, swine, and human strains over the past 20 years contributed to the 2009 swine influenza pandemic. Results of our study clearly clarify the historical drug resistance level of H1N1 influenza viruses around the world and demonstrated the evolution of adamantanes-resistant mutations in H1N1 influenza viruses. Our findings emphasize the necessity for monitoring the adamantanes susceptibility of H1N1 influenza viruses and draw attention to analyses of the evolution of drug-resistant H1N1 influenza variants.

Regulatory roles of galectins on influenza A virus and their potential as a therapeutic strategy

Galectins, are β-galactoside binding lectins expressed in numerous cells and are known to regulate various immune responses and cellular physiological functions. Galectins have been reported to participate in the regulation of several viral infections via carbohydrate‑dependent/independent manner. Galectins have displayed various regulatory functions on viral infection, however, the detailed mechanism remains unclear. More recently, some members of galectins have been reported to regulate influenza A virus (IAV) infection. In this review, we aim to analyze and summarize current findings regarding the role of galectins in IAV infection and their antiviral potential therapeutic application in the treatment of IAVs. The eligible articles were selected according to the PRISMA guidelines. Results indicate that Galectin-1(Gal-1), Galectin-3(Gal-3) and Galectin-9 (Gal-9) were found as the predominant galectins reported to participate in the regulation of IAVs infection. The inhibitory regulation of IAVs by these galectins occurred mainly through extracellular binding to glycosylated envelope proteins, further blocking the interaction between influenza envelope and sialic acid receptor, interacting with ligands or receptors on immune cells to trigger immunol or cellular response against IAVs, and endogenously interacting cellular components in the cytoplasm to activate inflammasome and autophagy. This study offers information regarding the multiple roles of galectins observed in IAVs infection and suggest that galectins has the potential to be used as therapeutic agents for IAVs.

Development of a molecularly imprinted microspheres-based microplate fluorescence method for detection of amantadine and rimantadine in chicken

In this study, molecularly imprinted microspheres of a type capable of recognising amantadine and rimantadine were first synthesised, and three fluorescent tracers based on dansyl chloride, fluorescein isothiocyanate and 5-carboxytetramethylrhodamine were also synthesised. These reagents were used to develop and optimise a direct competitive fluorescence method on conventional 96-well microplate for detection of the two analytes. Results showed that this method achieved simple operation procedure, rapid assay process (30 min), high sensitivity (limits of detection 0.04-0.05 ng mL^-1) and acceptable recycle performance (five times). After optimisation of several parameters, this method was used to detect amantadine and rimantadine in chicken muscle samples. Their recoveries from standards fortified blank samples were in the range of 62.3-93.7%. The analysis results for some real chicken samples were consistent with a confirmatory LC-MS/MS method. Therefore, this method could be used as a rapid, simple and accurate tool for routine screening the residues of amantadine and rimantadine in a large number of chicken muscle samples.

Anti-Influenza Activity of an Ethyl Acetate Fraction of a Rhus verniciflua Ethanol Extract by Neuraminidase Inhibition

Antigenic mismatch can cause influenza vaccines to be ineffective, and influenza viruses resistant to antiviral drugs are rising. Thus, development of antiviral agents against these viruses is an immediate need. Rhus verniciflua (RVS) has long been used in herbal medicine and as a nutritional supplement. The effect of RVS and its components on influenza virus has not, however, been reported. We found that RVS treatment significantly reduced viral replication when evaluated with green fluorescent protein- (GFP-) tagged virus (influenza A virus, A/PR/8/34-GFP) in Madin-Darby canine kidney (MDCK) cells. RVS showed significant inhibition of neuraminidase from A/PR/8/34. Subsequently, three fractions were prepared from an ethanolic crude extract of RVS. In vitro assays indicated that an ethyl acetate fraction (RVSE) was more potent than H₂O and CHCl₃ fractions. RVSE significantly suppressed influenza virus infection in MDCK cells via neuraminidase inhibition. Additionally, RVSE treatment inhibited expression of several virus proteins and decreased mortality of mice exposed to influenza A/PR/8/34 by 50% and reduced weight loss by 11.5%. Active components in RVSE were isolated, and 5-deoxyluteolin (5) and sulfuretin (7) demonstrate the highest neuraminidase inhibitory activity against influenza A virus. RVS, RVSE, and their constituents may be useful for the development of anti-influenza agents.

Covalent cucurbit[7]uril-dye conjugates for sensing in aqueous saline media and biofluids

Non-covalent chemosensing ensembles of cucurbit[n]urils (CBn) have been widely used in proof-of-concept sensing applications, but they are prone to disintegrate in saline media, e.g. biological fluids. We show here that covalent cucurbit[7]uril-indicator dye conjugates are buffer- (10× PBS buffer) and saline-stable (up to 1.4 M NaCl) and allow for selective sensing of Parkinson's drug amantadine in human urine and saliva, where the analogous non-covalent CB7⊃dye complex is dysfunctional. The in-depth analysis of the covalent host-dye conjugates in the gas-phase, and deionized versus saline aqueous media revealed interesting structural, thermodynamic and kinetic effects that are of general interest for the design of CBn-based supramolecular chemosensors and systems. This work also introduces a novel high-affinity indicator dye for CB7 through which fundamental limitations of indicator displacement assays (IDA) were exposed, namely an impractical slow equilibration time. Unlike non-covalent CBn⊃dye reporter pairs, the conjugate chemosensors can also operate through a SN2-type guest-dye exchange mechanism, which shortens assay times and opens new avenues for tailoring analyte-selectivity.

Combinatory Treatment with Oseltamivir and Itraconazole Targeting Both Virus and Host Factors in Influenza A Virus Infection

Influenza virus infections and their associated morbidity and mortality are a major threat to global health. Vaccination is an effective influenza prevention measure; however, the effectiveness is challenged by the rapid changes in the influenza virus genome leading to viral adaptation. Emerging viral resistance to the neuraminidase inhibitor oseltamivir limits the treatment of acute influenza infections. Targeting influenza virus-host interactions is a new and emerging field, and therapies based on the combination of virus- and host-directed drugs might significantly improve treatment success. We therefore assessed the combined treatment with oseltamivir and the repurposed antifungal drug itraconazole on infection of polarized broncho-epithelial Calu-3 cells with pdm09 or Panama influenza A virus strains. We detected significantly stronger antiviral activities in the combined treatment compared to monotherapy with oseltamivir, permitting lower concentrations of the drug than required for the single treatments. Bliss independence drug interaction analysis indicated that both drugs acted independently of each other. The additional antiviral effect of itraconazole might safeguard patients infected with influenza virus strains with heightened oseltamivir resistance.

Site-directed mutations of anti-amantadine scFv antibody by molecular dynamics simulation: prediction and validation

A recombinant single-chain variable fragment (scFv) antibody was produced from a hybridoma cell strain secreting the monoclonal antibody for amantadine (AMD), and then its recognition mechanisms for AMD were studied using the molecular docking and molecular dynamics. Complex dockings revealed that three regions are involved in antibody recognition; framework 2 of the VL chain (LFR2) GLU40 and TYR42, complementarity-determining region of the VL chain (LCDR3) TYR116, and framework 2 of the VH chain (HFR2) HIS40 and TRP52 were the key amino acid residues. The results of molecular dynamics show that the most important amino acid residues in the interaction between AMD and scFv are HIS40 and TYR116. On the basis of the results of virtual mutation, the scFv antibody was evolved by directional mutagenesis of amino acid residue GLY107 to PHE. Indirect competitive ELISA (icELISA) results indicated that the scFv mutant had highly increased affinity for AMD with up to 3.9-fold improved sensitivity. Thus, the scFv antibody can be applied for mechanistic studies of intermolecular interactions, and our work offered affinity maturated antibodies by site mutations, which were beneficial for valuable anti-AMD antibody design and preparation in future.

Inventory of molecular markers affecting biological characteristics of avian influenza A viruses

Avian influenza viruses (AIVs) circulate globally, spilling over into domestic poultry and causing zoonotic infections in humans. Fortunately, AIVs are not yet capable of causing sustained human-to-human infection; however, AIVs are still a high risk as future pandemic strains, especially if they acquire further mutations that facilitate human infection and/or increase pathogenesis. Molecular characterization of sequencing data for known genetic markers associated with AIV adaptation, transmission, and antiviral resistance allows for fast, efficient assessment of AIV risk. Here we summarize and update the current knowledge on experimentally verified molecular markers involved in AIV pathogenicity, receptor binding, replicative capacity, and transmission in both poultry and mammals with a broad focus to include data available on other AIV subtypes outside of A/H5N1 and A/H7N9.

Antiviral activity of ethanol extract of Geranii Herba and its components against influenza viruses via neuraminidase inhibition

Influenza viruses are a serious threat to human health, causing numerous deaths and pandemics worldwide. To date, neuraminidase (NA) inhibitors have primarily been used to treat influenza. However, there is a growing need for novel NA inhibitors owing to the emergence of resistant viruses. Geranii Herba (Geranium thunbergii Siebold et Zuccarini), which is edible, has long been used in a variety of disease treatments in Asia. Although recent studies have reported its various pharmacological activities, the effect of Geranii Herba and its components on influenza viruses has not yet been reported. In this study, Geranii Herba ethanol extract (GHE) and its component geraniin showed high antiviral activity against influenza A strain as well as influenza B strain, against which oseltamivir has less efficacy than influenza A strain, by inhibiting NA activity following viral infection in Madin–Darby canine kidney cells. Thus, GHE and its components may be useful for the development of anti-influenza drugs.

Fabrication and evaluation of a label-free piezoelectric immunosensor for sensitive and selective detection of amantadine in foods of animal origin

A label-free piezoelectric immunosensor was fabricated and applied to the detection of the antiviral drug amantadine (AM) in foods of animal origin. Experimental parameters associated with the fabrication and measurement process were optimized and are discussed here in detail. The proposed piezoelectric sensor is based on an immunosuppression format and uses a portable quartz crystal microbalance (QCM) chip. It was found to provide a good response to AM, with a sensitivity and limit of detection (LOD) of 33.9 and 1.3 ng mL^-1, respectively, as well as low cross-reactivity (CR, < 0.01%) with AM analogues. The immunosensor was further applied to quantify AM at three levels in spiked samples of typical foods of animal origin, and yielded recoveries of 83.2-93.4% and standard deviations (SDs, n = 3) of 2.4-4.5%, which are comparable to the results (recoveries: 82.6-94.3%; SDs: 1.7-4.2%) obtained using a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. Furthermore, the piezoelectric immunosensing chip can be regenerated multiple (at least 20) times with low signal attenuation (about 10%). A sample analysis can be completed within 50 min (sample pretreatment: about 40 min, QCM measurement: 5 min). These results demonstrate that the developed piezoelectric immunosensor provides a sensitive, accurate, portable, and low-cost analytical strategy for the antiviral drug AM in foods of animal origin, and this label-free detection method could also be applied to analyze other targets in the field of food safety. Graphical abstract.

Discovery of potential transcriptional biomarkers in broiler chicken for detection of amantadine abuse based on RNA sequencing technology

The aim of this study was to identify candidate transcriptional biomarkers so as to provide a new method for monitoring amantadine residues during the feeding of broiler chicken. RNA sequencing (RNA-seq) and bioinformatic analyses were conducted to examine the transcriptomic changes and screen differentially expressed genes (DEGs) in broiler chicken breast muscle and liver tissues treated with amantadine. The results indicated that a total of 170 DEGs were screened from broiler chicken breast muscle tissues after amantadine was fed. Among the genes, 120 were up-regulated and 50 were down-regulated. The gene ontology (GO) terms for these genes mainly existed in the areas of hydrolase activity, immune reaction and chemokine activity. The significantly enriched pathways in the Kyoto Encyclopedia for Genes and Genomes (KEGG) were in phagosomes, cell adhesion molecules (CAMs), lysosomes and extracellular matrix (ECM) receptors. From the broiler chicken liver tissues, 172 DEGs were screened, among which 116 were up-regulated and 56 were down-regulated. The GO terms of these DEGs were related to functions such as catalytic activities, metabolic activities, oxidation-reduction activities, immune reactions and cofactor binding. The significantly enriched KEGG pathways existed in metabolism, CAM, ECM receptor reaction and drug metabolism-cytochrome P450. According to the fold-change (FC), significance levels, functional annotations and possible biological processes of DEGs, 11 and 9 candidate DEGs related to amantadine treatment were further screened from broiler chicken breast muscle and liver tissues, respectively. In addition, the quantitative real-time polymerase chain reaction (qRT-PCR) verification showed exactly concordant results with the RNA-seq data. Principal components analysis (PCA) on the qRT-PCR data resulted in the separation of treated samples from the control samples in both tissues. The results provided a basis for identification of transcriptional biomarkers for detecting amantadine residues in broiler chicken breast muscle and liver tissues.

Screening hundreds of emerging organic pollutants (EOPs) in surface water from the Yangtze River Delta (YRD): Occurrence, distribution, ecological risk

Increased synthetic chemical production and diversification in developing countries caused serious aquatic pollution worldwide with emerging organic pollutants (EOPs) detected in surface water rising health concerns to human and aquatic ecosystem even at low ng/L concentration with long-term exposure. The Yangtze River Delta (YRD) area serves agriculture and industry for people in eastern China. However, the current knowledge on the occurrence and ecological risk of diverse EOPs which are present in the aquatic environment is limited. This study was to investigate the complexity and diversity of EOPs in surface water from 28 sampling sites, which were selected to represent urban, industrial or agriculture areas in the YRD area. In total 484 chemicals were analyze by a target screening approach using liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS). 181 out of 484 EOPs were detected at least one site in the YRD area, and 44 analytes, mostly industrial chemicals and pesticides, were ubiquitous at all sampling sites. Most EOPs were industrial chemicals with 1H-benzotriazole and organophosphate flame retardants (PFRs) as the chemicals with highest concentrations. For 21 pesticides, mostly herbicides, maximum concentrations of atrazine and isoproturon were above the annual average environmental quality standards of Europe. Amantadine and DEET were the dominant pharmceuticals and personal care products (PPCPs) in the YRD area. Compared to urban areas (mostly in Qinhuai River), chemical profiles from industrial areas were more complex. Industrial activities likely have a strong impact on the composition of chemical mixtures in surface water from the YRD area. ISO E Super, 4-methylbenzylidene camphor and clotrimazole detected in this study are potentially persistent and bioaccumulative chemicals. Furthermore, results of risk assessment showed that hazard quotients of dimethyldioctadecylammonium, didecyldimethylammonium and octocrylene were higher than one and occur frequently, which indicates possibly adverse effects on fish species in the YRD area.

Comparison of antiviral resistance across acute and chronic viral infections

Antiviral therapy can lead to drug resistance, but multiple factors determine the frequency of drug resistance mutations and the clinical consequences. When chronic infections caused by Human Immunodeficiency Virus (HIV), Hepatitis C Virus (HCV) and Hepatitis B Virus (HBV) are compared with acute infections such as influenza virus, respiratory syncytial virus (RSV), and other respiratory viruses, there are similarities in how and why antiviral resistance substitutions occur, but the clinical significance can be quite different. Emergence of resistant variants has implications for design of new therapeutics, treatment guidelines, clinical trial design, resistance monitoring, reporting, and interpretation. In this discussion paper, we consider the molecular factors contributing to antiviral drug resistance substitutions, and a comparison is made between chronic and acute infections. The implications of resistance are considered for clinical trial endpoints and public health, as well as the requirements for therapeutic monitoring in clinical practice with acute viral infections.

Molecular epidemiological survey and complete genomic phylogenetic analysis of H6 subtype avian influenza viruses in poultry in China from 2011 to 2016

To investigate the prevalence and evolution of the H6 subtype avian influenza viruses (AIVs) circulating in poultry in China from 2011 to 2016, 11 molecular epidemiological surveys was performed in this study. In total, 893 H6 subtype viral strains were isolated from 67,639 swab samples and 360 environmental samples. From these strains, 35 representative strains were selected and their whole genomic sequences determined. According to a phylogenetic analysis and molecular characterization, all 35 viral strains belonged to the Eurasian avian lineage. All of them were categorized as 'low pathogenic' and a few strains had some bioinformatical mutations. This epidemiological survey shows that the prevalence of H6 subtype AIVs increased from 2012 to 2016 in China, and suggests that infections by H6 subtype AIVs in China has increased in recent years.

Unlocking pandemic potential: prevalence and spatial patterns of key substitutions in avian influenza H5N1 in Egyptian isolates

Background

Avian influenza H5N1 has a high human case fatality rate, but is not yet well-adapted to human hosts. Amino acid substitutions currently circulating in avian populations may enhance viral fitness in, and thus viral adaptation to, human hosts. Substitutions which could increase the risk of a human pandemic (through changes to host specificity, virulence, replication ability, transmissibility, or drug susceptibility) are termed key substitutions (KS). Egypt represents the epicenter of human H5N1 infections, with more confirmed cases than any other country. To date, however, there have not been any spatial analyses of KS in Egypt.

Methods

Using 925 viral samples of H5N1 from Egypt, we aligned protein sequences and scanned for KS. We geocoded isolates using dasymetric mapping, then carried out geospatial hot spot analyses to identify spatial clusters of high KS detection rates. KS prevalence and spatial clusters were evaluated for all detected KS, as well as when stratified by phenotypic consequence.

Results

A total of 39 distinct KS were detected in the wild, including 17 not previously reported in Egypt. KS were detected in 874 samples (94.5%). Detection rates varied by viral protein with most KS observed in the surface hemagglutinin (HA) and neuraminidase (NA) proteins, as well as the interior non-structural 1 (NS1) protein. The most frequently detected KS were associated with increased viral binding to mammalian cells and virulence. Samples with high overall detection rates of KS exhibited statistically significant spatial clustering in two governorates in the northwestern Nile delta, Alexandria and Beheira.

Conclusions

KS provide a possible mechanism by which avian influenza H5N1 could evolve into a pandemic candidate. With numerous KS circulating in Egypt, and non-random spatial clustering of KS detection rates, these findings suggest the need for increased surveillance in these areas.

A Highly Selective and Strong Anti-Interference Host-Guest Complex as Fluorescent Probe for Detection of Amantadine by Indicator Displacement Assay

Amantadine (AMA) and its derivatives are illicit veterinary drugs that are hard to detect at very low concentrations. Developing a fast, simple and highly sensitive method for the detection of AMA is highly in demand. Here, we designed an anthracyclic compound (ABAM) that binds to a cucurbit[7]uril (CB[7]) host with a high association constant of up to 8.7 × 10⁸ M⁻¹. The host-guest complex was then used as a fluorescent probe for the detection of AMA. Competition by AMA for occupying the cavity of CB[7] allows ABAM to release from the CB[7]-ABAM complex, causing significant fluorescence quenching of ABAM (indicator displacement assay, IDA). The linear range of the method is from 0.000188 to 0.375 μg/mL, and the detection limit can be as low as 6.5 × 10⁻⁵ μg/mL (0.35 nM). Most importantly, due to the high binding affinity between CB[7] and ABAM, this fluorescence host-guest system shows great anti-interference capacity. Thus, we are able to accurately determine the concentration of AMA in various samples, including pharmaceutical formulations.

Highly sensitive visual detection of amantadine residues in poultry at the ppb level: A colorimetric immunoassay based on a Fenton reaction and gold nanoparticles aggregation

Colorimetric biosensors for the on-site visual detection of veterinary drug residues are required for food control in developing countries and other resource-constrained areas, where sophisticated instruments may not be available. In this study, we developed a highly sensitive immunoassay for amantadine residues in poultry. By introducing a novel signal generation strategy into an indirect competitive immunoassay, a highly sensitive assay for amantadine residues in chicken was achieved for naked eye readout at the part per billion (ppb) level. Signal amplification was achieved in the designed immunoassay by combining conventional indirect competitive enzyme-linked immunosorbent assay, Fenton reaction-regulated oxidation of cysteine, and gold nanoparticle aggregation. Therefore, the cascade reaction remarkably enhanced the assay sensitivity and led to a pronounced color change from red to dark purple in the solution, which could be easily distinguished with the naked eye even at approximately 1 μg kg^-1 in poultry muscle. Moreover, the color change can be quantitatively assayed with a classic high-throughput plate reader for contaminated poultry samples. The limit of detection (LOD) was 0.51 nM (0.095 ng mL^-1). The recovery rates for spiked chicken samples ranged from 78% to 84% with relative standard deviations <15%. Therefore, we propose that this immunoassay could be generally applicable for on-site detection in the field of food control.

Simultaneous determination of amantadine and rimantadine in feed by liquid chromatography-Qtrap mass spectrometry with information-dependent acquisition

A sensitive method for simultaneous determination of amantadine and rimantadine in feed was developed using an ultra-high-performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UHPLC-Qtrap-MS) in the multiple reaction monitoring information-dependent acquisition-enhanced product ion (MRM-IDA-EPI) mode, and employing the mixed cation exchange (MCX) solid-phase extraction column as sample cleanup and amantadine-d₁₅ and rimantadine-d₄ as internal standards, respectively. Compared to traditional MRM mode, for the targeted drugs in feed simultaneously both the secondary mass spectra and MRM information can be obtained using UHPLC-Qtrap-MS with MRM-IDA-EPI mode, and thus more accurate qualitative confirmation results achieved even at lower concentration of 0.2 μg/L in acceptable purity fit values. After optimization of sample preparation, good linearities (R > 0.9994) were obtained over the concentration range from 1 to 200 μg/L for amantadine and rimantadine. The precision was validated by intra-day and inter-day, and the relative standard deviations were all within 9.61%. Mean recoveries ranged from 76.1 to 112% at spiked concentrations of 0.5-100 μg/kg in three types of feed samples, including formula feed and complex concentrated feed for pigs and premix feed for chicken. The limits of detection (LODs) and quantification (LOQs) were 0.2 and 0.5 μg/kg for both drugs, respectively. The application in real feed samples further proved the accuracy and reliability of the developed method. This method provides an important tool to detect illegal uses of amantadine and rimantadine in feed. Graphical abstract Simultaneous quantitation and qualitative confirmation of amantadine and rimantadine in feed by MRM-IDA-EPI.

An electrodeposited molecularly imprinted quartz crystal microbalance sensor sensitized with AuNPs and rGO material for highly selective and sensitive detection of amantadine

In the present work, a new amantadine (AM) imprinted quartz crystal microbalance (QCM) sensor sensitized by Au nanoparticles (AuNPs) and reduced graphene oxide (rGO) material was fabricated by electrodeposition in the presence of o-aminothiophenol (o-AT) by cyclic voltammetry scanning. AuNPs and graphene, with the advantages of great chemical stability, electrical conductivity, and large surface area, show exceptionally high sensitivity. The results of different modifications of the QCM sensor fabrication process were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. Under the optimal experimental conditions, the frequency shift of the MIP-QCM sensor showed a linear relationship with the concentration of the AM template in the range of 1.0 × 10⁻⁵ to 1.0 × 10⁻³ mmol L⁻¹ with a limit of detection (LOD) of 5.40 × 10⁻⁶ mmol L⁻¹. The imprinting factor for AM reached 7.1, the selectivity coefficient for the analogues rimantadine (RT), adamantine (AMT) and 1-chloroadamantane (CMT) were 7.3, 5.6, and 6.1, respectively. Here, a highly sensitive, selective and stable QCM sensor prepared via the imprinting approach is reported for the first time for detection of AM from animal-derived food samples.

In the present work, a new amantadine imprinted quartz crystal microbalance sensor sensitized by Au nanoparticles and reduced graphene oxide material was fabricated by electrodeposition of o-aminothiophenol by cyclic voltammetry scanning.

Isolation and characterization of H4N6 avian influenza viruses from mallard ducks in Beijing, China

The novel H7N9 influenza virus, which has caused severe disease in humans in China, is a reassortant with surface genes derived from influenza viruses in wild birds. This highlights the importance of monitoring influenza viruses in these hosts. However, surveillance of influenza virus in wild birds remains very limited in China. In this study, we isolated four H4N6 avian influenza viruses (AIVs) from mallard ducks in Beijing Wetland Park, which is located on the East Asia–Australasia migratory flyway. The gene segments of these Chinese H4N6 viruses were closest to AIVs in wild birds from Mongolia or the Republic of Georgia, indicating the interregional AIV gene flow among these countries. All of our isolates belonged to a novel genotype that was different from other H4N6 viruses isolated in China. We further evaluated the virulence and transmission of two representative H4N6 strains in mammalian models. We found that both of these H4N6 viruses replicated efficiently in mice without adaptation. Additionally, these two strains had a 100% transmission rate in guinea pigs via direct contact, but they had not acquired respiratory droplet transmissibility. These results reveal the potential threat to human health of H4N6 viruses in migratory birds and the need for enhanced surveillance of AIVs in wild birds.

Characterization of Novel Reassortant Influenza A (H5N2) Viruses Isolated from Poultry in Eastern China, 2015

Recently, novel variants of H5 highly pathogenic avian influenza viruses (AIVs) have been frequently isolated from poultry and wild birds in Asia, Europe and North America. Live poultry markets (LPMs) play an important role in the dissemination of influenza viruses. Four H5N2 AIVs were isolated from poultry during surveillance of AIVs in LPMs in Eastern China, in 2015. Whole-genome sequencing, combined with phylogenetic and antigenic analyses were performed to characterize these viruses. These H5N2 viruses had undergone extensive reassortment resulting in two genetic groups of viruses in poultry. These viruses exhibited slightly pathogenicity in mice, and replicated without prior adaptation. The continued circulation of these novel H5N2 viruses may represent a threat to human health.

Development of a competitive immunochromatographic assay for the sensitive detection of amantadine in chicken muscle

Amantadine (AMD) is a prohibitive veterinary medicine in the entire world. In this study, a sensitive colloidal gold immunochromatographic assay (CGICA) was established for the rapid semi-quantitative detection of AMD in chicken muscle. Under optimal conditions, the detection results were obtained in 12min with a limit of detection for 1.80ng/mL. CGICA presented a good linear range from 2.5ng/mL to 25ng/mL, with only 11.5% cross-reactivity with rimantadine. The recovery rates for the fortified samples were ranged from 81% to 120%. The coefficient of variation of the intra-assay and inter-assay was less than 15%. The accuracy of CGICA was confirmed by systematically comparing the result of the proposed method with enzyme-linked immunosorbent assay and ultra-high-performance liquid chromatography-tandem mass spectrometry. Given the advantages of its simplicity, convenience, and speediness, the proposed CGICA is suitable for the on-site rapid detection of AMD in chicken muscle.

Genesis and Dissemination of Highly Pathogenic H5N6 Avian Influenza Viruses

Clade 2.3.4.4 highly pathogenic avian influenza viruses (H5Nx) have spread from Asia to other parts of the world. Since 2014, human infections with clade 2.3.4.4 highly pathogenic avian influenza H5N6 viruses have been continuously reported in China. To investigate the genesis of the virus, we analyzed 123 H5 or N6 environmental viruses sampled from live-poultry markets or farms from 2012 to 2015 in Mainland China. Our results indicated that clade 2.3.4.4 H5N2/N6/N8 viruses shared the same hemagglutinin gene as originated in early 2009. From 2012 to 2015, the genesis of highly pathogenic avian influenza H5N6 viruses occurred via two independent pathways. Three major reassortant H5N6 viruses (reassortants A, B, and C) were generated. Internal genes of reassortant A and B viruses and reassortant C viruses derived from clade 2.3.2.1c H5N1 and H9N2 viruses, respectively. Many mammalian adaption mutations and antigenic variations were detected among the three reassortant viruses. Considering their wide circulation and dynamic reassortment in poultry, we highly recommend close monitoring of the viruses in poultry and humans. IMPORTANCE Since 2014, clade 2.3.4.4 highly pathogenic avian influenza (H5Nx) viruses have caused many outbreaks in both wild and domestic birds globally. Severe human cases with novel H5N6 viruses in this group were also reported in China in 2014 and 2015. To investigate the genesis of the genetic diversity of these H5N6 viruses, we sequenced 123 H5 or N6 environmental viruses sampled from 2012 to 2015 in China. Sequence analysis indicated that three major reassortants of these H5N6 viruses had been generated by two independent evolutionary pathways. The H5N6 reassortant viruses had been detected in most provinces of southern China and neighboring countries. Considering the mammalian adaption mutations and antigenic variation detected, the spread of these viruses should be monitored carefully due to their pandemic potential.

Simultaneous determination of amantadine, rimantadine, and memantine in processed products, chicken tissues, and eggs by liquid chromatography with tandem mass spectrometry

A simultaneous determination of amantadine, rimantadine, and memantine in processed products (deep-fried chicken, fried chicken, fried quail egg, and grilled chicken) with liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed. This new method was also applicable for chicken tissue (muscle, liver, and gizzard) and eggs. The chromatographic separation was performed on a Kinetex^® XB-C18 core-shell technology column using a mobile phase of acetonitrile and 0.1% formic acid in a 10mmol/L ammonium formate solution, resulting in the complete separation of isomers (rimantadine and memantine) and any other obstructive peaks from the sample matrices. Sample preparation was performed by a modified QuEChERS method using acetonitrile and a 0.1% acetic acid extraction solution and cleaned using an Oasis^® MCX cartridge. The sample matrix had no effect on the identification of the compounds. For quantification, an external solvent calibration curve was used. This new method exhibited good accuracy ranging from 79.9% to 91.5%. The relative standard deviation of repeatability (RSD_r) ranged from 1.2% to 3.6% and the relative standard deviation of within-laboratory reproducibility (RSD_WR) ranged from 1.3% to 6.0%. These standard deviations satisfied the criteria for Japanese validation guidelines. The limit of quantification (LOQ) was 1.0μg/kg for all samples. Analyte residues were not detected in 55 samples using the validated method.

Biological fitness and natural selection of amantadine resistant variants of avian influenza H5N1 viruses

Outbreaks caused by the highly pathogenic H5N1 avian influenza virus (A/H5N1) devastated the poultry industry in several countries and posed a significant pandemic threat. In addition to culling of infected poultry and vaccination, amantadine has been applied in poultry in some countries to control the spread of the virus. The prevalence of the amantadine resistance marker at position 31 (Ser31Asn) of the M2 protein increased over time. However, little is known about the biological fitness and selection of H5N1 amantadine resistant strains over their sensitive counterparts. Here, using reverse genetics we investigated the biological impact of Ser31Asn in M2 commonly seen in viruses in clade 2.2.1.1 in farmed poultry in Egypt. Findings of the current study indicated that the resistance to amantadine conferred by Asn31 evolved rapidly after the application of amantadine in commercial poultry. Both the resistant and sensitive strains replicated at similar levels in avian cell culture. Asn31 increased virus entry into the cells and cell-to-cell spread and was genetically stable for several passages in cell culture. Moreover, upon co-infection of cell culture resistant strains dominated sensitive viruses even in the absence of selection by amantadine. Together, rapid emergence, stability and domination of amantadine-resistant variants over sensitive strains limit the efficacy of amantadine in poultry.

Re-emergence of amantadine-resistant variants among highly pathogenic avian influenza H5N1 viruses in Egypt

Highly pathogenic avian influenza (HPAI) H5N1 virus continues to undergo substantial evolution. Emergence of antiviral resistance among H5N1 avian influenza viruses is a major challenge in the control of pandemic influenza. Numerous studies have focused on the genetic and evolutionary dynamics of the hemagglutinin and neuraminidase genes; however, studies on the susceptibility of HPAI H5N1 viruses to amantadine and genetic diversity of the matrix (M) gene are limited. Accordingly, we studied the amantadine susceptibility of the HPAI H5N1 viruses isolated in Egypt during 2006-2015 based on genotypic and phenotypic characteristics. We analyzed data on 253 virus sequences and constructed a phylogenetic tree to calculate selective pressures on sites in the M2 gene associated with amantadine-resistance among different clades. Selection pressure was identified in the transmembrane domain of M2 gene at positions 27 and 31. Amantadine-resistant variants emerged in 2007 but were not circulating between 2012 and 2014. By 2015, amantadine-resistant HPAI H5N1 viruses re-emerged. This may be associated with the uncontrolled prescription of amantadine for prophylaxis and control of avian influenza infections in the poultry farm sector in Egypt. More epidemiological research is required to verify this observation.

Identification of combinatorial host-specific signatures with a potential to affect host adaptation in influenza A H1N1 and H3N2 subtypes

BACKGROUND

The underlying strategies used by influenza A viruses (IAVs) to adapt to new hosts while crossing the species barrier are complex and yet to be understood completely. Several studies have been published identifying singular genomic signatures that indicate such a host switch. The complexity of the problem suggested that in addition to the singular signatures, there might be a combinatorial use of such genomic features, in nature, defining adaptation to hosts.

RESULTS

We used computational rule-based modeling to identify combinatorial sets of interacting amino acid (aa) residues in 12 proteins of IAVs of H1N1 and H3N2 subtypes. We built highly accurate rule-based models for each protein that could differentiate between viral aa sequences coming from avian and human hosts. We found 68 host-specific combinations of aa residues, potentially associated to host adaptation on HA, M1, M2, NP, NS1, NEP, PA, PA-X, PB1 and PB2 proteins of the H1N1 subtype and 24 on M1, M2, NEP, PB1 and PB2 proteins of the H3N2 subtypes. In addition to these combinations, we found 132 novel singular aa signatures distributed among all proteins, including the newly discovered PA-X protein, of both subtypes. We showed that HA, NA, NP, NS1, NEP, PA-X and PA proteins of the H1N1 subtype carry H1N1-specific and HA, NA, PA-X, PA, PB1-F2 and PB1 of the H3N2 subtype carry H3N2-specific signatures. M1, M2, PB1-F2, PB1 and PB2 of H1N1 subtype, in addition to H1N1 signatures, also carry H3N2 signatures. Similarly M1, M2, NP, NS1, NEP and PB2 of H3N2 subtype were shown to carry both H3N2 and H1N1 host-specific signatures (HSSs).

CONCLUSIONS

To sum it up, we computationally constructed simple IF-THEN rule-based models that could distinguish between aa sequences of avian and human IAVs. From the rules we identified HSSs having a potential to affect the adaptation to specific hosts. The identification of combinatorial HSSs suggests that the process of adaptation of IAVs to a new host is more complex than previously suggested. The present study provides a basis for further detailed studies with the aim to elucidate the molecular mechanisms providing the foundation for the adaptation process.

Hemagglutinin-targeting Artificial MicroRNAs Expressed by Adenovirus Protect Mice From Different Clades of H5N1 Infection

Influenza virus (IV) is a continuously evolving virus that widely spreads in humans and contributes to substantial morbidity and mortality. Re-emergence of human infection with avian influenza virus H5N1 poses extra challenge to IV control. Artificial microRNA (amiRNA)-mediated RNA interference has become a powerful antiviral approach due to its high specificity and rapid effect. Here, we designed several amiRNAs targeting the hemagglutinin gene of H5N1, a major determinant of pathogenicity. Expression and delivery efficiency were enhanced by presenting functional amiRNA with chimpanzee adenovirus serotype 68 (AdC68). One amiRNA, HA-1405, significantly limited H5N1 replication in vitro and inhibited 96.7% of clade 2.3.2 replication. AdC68-conjugated HA-1405 treatment remarkably decreased different clades of H5N1 plaque formation in Madin–Darby canine kidney cells. Moreover, prophylactic administration with rAd(HA-1405) markedly alleviated clinical symptoms and reduced ~3- to 40-folds of lung viral RNA copies against four clades of H5N1 in Institute of Cancer Research (ICR) mice. Our results further showed that rAd(HA-1405) conferred 70 and 40% immediate protection against lethal clade 2.3.2 and clade 2.3.4 H5N1 challenge, respectively. In conclusion, these data provided information that HA-targeting amiRNA delivered by AdC68 could be pursued as a potential agent for highly pathogenic avian influenza viruses prevention.

Genotypic evolution and antigenicity of H9N2 influenza viruses in Shanghai, China

H9N2 influenza viruses have been circulating in China since 1994, but a systematic investigation of H9N2 in Shanghai has not previously been undertaken. Here, using 14 viruses we isolated from poultry and pigs in Shanghai during 2002 and 2006-2014, together with the commercial vaccine A/chicken/Shanghai/F/1998 (Ck/SH/F/98), we analyzed the evolution of H9N2 influenza viruses in Shanghai and showed that all 14 isolates originated from Ck/SH/F/98 antigenically. We evaluated the immune protection efficiency of the vaccine. Our findings demonstrate that H9N2 viruses in Shanghai have undergone extensive reassortment. Various genotypes emerged in 2002, 2006 and 2007, while during 2009-2014 only one genotype was found. Four antigenic groups, A-D, could be identified among the 14 isolates and a variety of antigenically distinct H9N2-virus-derived avian influenza viruses (AIVs) circulated simultaneously in Shanghai during this period. Challenge experiments using vaccinated chickens indicated that the vaccine prevented shedding of antigenic group A and B viruses, but not those of the more recent groups C and D. Genetic analysis showed that compared to the vaccine strain, representative viruses of antigenic groups C and D possess greater numbers of amino acid substitutions in the hemagglutinin (HA) protein than viruses in antigenic groups A and B. Many of these substitutions are located in antigenic sites. Our results indicate that the persistence of H9N2 AIV in China might be due to incomplete vaccine protection and that the avian influenza vaccine should be regularly evaluated and updated to maintain optimal protection.

Inhibition of neuraminidase by Ganoderma triterpenoids and implications for neuraminidase inhibitor design

Neuraminidase (NA) inhibitors are the dominant antiviral drugs for treating influenza in the clinic. Increasing prevalence of drug resistance makes the discovery of new NA inhibitors a high priority. Thirty-one triterpenoids from the medicinal mushroom Ganoderma lingzhi were analyzed in an in vitro NA inhibition assay, leading to the discovery of ganoderic acid T-Q and TR as two inhibitors of H5N1 and H1N1 NAs. Structure-activity relationship studies revealed that the corresponding triterpenoid structure is a potential scaffold for the design of NA inhibitors. Using these triterpenoids as probes we found, through further in silico docking and interaction analysis, that interactions with the amino-acid residues Arg292 and/or Glu119 of NA are critical for the inhibition of H5N1 and H1N1. These findings should prove valuable for the design and development of NA inhibitors.