Anionic polymer, poly(methyl vinyl ether–maleic anhydride)-coated beads-based capture of human influenza A and B virus

Exploring flexibility, intermolecular interactions and ADMET profiles of anti-influenza agent isorhapontigenin: A quantum chemical and molecular docking study

Isorhapontigenin (IRPG) drug emerges as promising efficient inhibitor for H1N1 and H3N2 subtypes which belong to influenza A virus; reported with IC₅₀ value of 35.62 and 63.50 μM respectively. When experimental data are compared to the predicted geometrical parameters and vibrational assignments (FT-IR and FT-Raman), the findings indicated a strong correlation. The absorption bands of π→π∗ transitions are revealed through UV-Vis electronic properties; this confirms that the IRPG molecule shows strong bands. Through NBO and HOMO-LUMO analysis, the kinetic stability and chemical reactivity of the IRPG molecule were investigated. By using an MEP map, the IRPG's electrophilic and nucleophilic site selectivity was assessed. In a molecular docking investigation, the IRPG molecule shows a stronger inhibition constant and binding affinity for the H1N1 and H3N2 influenza virus. The IRPG molecule thus reveals good biological actions in nature and can be used as a potential therapeutic drug candidate for H1N1 and H3N2 virus A influenza.

Evaluation of Virucidal Efficacy of Human Norovirus Using Combined Sprayed Slightly Acidic Electrolyzed Water and Ultraviolet C-Light-Emitting Diode Irradiation Treatment Based on Optimized Capture Assay for Quantitative RT-qPCR

Slightly acidic electrolyzed water (SAEW), an effective non-thermal virucidal treatment, is used widely to prevent infectious viral cross-contamination. Surface disinfection technologies using ultraviolet C-light-emitting diode (UVC-LED) irradiation have recently attracted considerable attention. The SAEW sprayer technique is an efficient approach to preventing the spread of infectious viral pathogens in the public healthcare sector. Therefore, we investigated a small-scale system comprising sprayed SAEW disinfection combined with UVC-LED irradiation to inactivate the human norovirus (HuNoV) in the environment. A stainless-steel surface was inoculated with a HuNoV genogroup II genotype 4 (GII.4) to achieve maximum reduction values of 3.21 log10 genomic copies. For optimal disinfection conditions, the response surface methodology based on the Box–Behnken design revealed that the specific treatment conditions for inactivation of HuNoV GII.4 were an SAEW droplet volume of 180 μL, 30 ppm available chlorine concentration of SAEW, and a UVC-LED exposure dose of 2 mJ/cm². The results indicate that the combined disinfection treatment could efficiently prevent the spread of HuNoVs in environment. Furthermore, the quadratic polynomial equations of the 3-D response surface can be employed to predict the effects of combined disinfection treatment on HuNoV contamination on environmental surfaces. Therefore, sprayed SAEW disinfection combined with UVC-LED irradiation proposed in this study may offer insights for designing optimal control strategies and techniques to prevent the transmission of infectious diseases, particularly HuNoV.

Modern Techniques for the Isolation of Extracellular Vesicles and Viruses

Extracellular signaling is pivotal to maintain organismal homeostasis. A quickly emerging field of interest within extracellular signaling is the study of extracellular vesicles (EV), which act as messaging vehicles for nucleic acids, proteins, metabolites, lipids, etc. from donor cells to recipient cells. This transfer of biologically active material within a vesicular body is similar to the infection of a cell through a virus particle, which transfers genetic material from one cell to another to preserve an infection state, and viruses are known to modulate EV. Although considerable heterogeneity exists within EV and viruses, this review focuses on those that are small (< 200 nm in diameter) and of relatively low density (< 1.3 g/mL). A multitude of isolation methods for EV and virus particles exist. In this review, we present an update on methods for their isolation, purification, and phenotypic characterization. We hope that the information we provide will be of use to basic science and clinical investigators, as well as biotechnologists in this emerging field. Graphical Abstract.

Concentration of viruses and electron microscopy

Nearly all lethal viral outbreaks in the past two decades were caused by newly emerging viruses. Viruses are often studied by electron microscopy (EM), which provides new high-resolution data on the structure of viral particles relevant to both fundamental virology and practical pharmaceutical nanobiotechnology. Electron microscopy is also applied to ecological studies to detect viruses in the environment, to analysis of technological processes in the production of vaccines and other biotechnological components, and to diagnostics. Despite the advances in more sensitive methods, electron microscopy is still in active use for diagnostics. The main advantage of EM is the lack of specificity to any group of viruses, which allows working with unknown materials. However, the main limitation of the method is the relatively high detection limit (107 particles/mL), requiring viral material to be concentrated. There is no most effective universal method to concentrate viruses. Various combinations of methods and approaches are used depending on the virus and the goal. A modern virus concentration protocol involves precipitation, centrifugation, filtration, and chromatography. Here we describe the main concentrating techniques exemplified for different viruses. Effective elution techniques are required to disrupt the bonds between filter media and viruses in order to increase recovery. The paper reviews studies on unique traps, magnetic beads, and composite polyaniline and carbon nanotubes, including those of changeable size to concentrate viral particles. It also describes centrifugal concentrators to concentrate viruses on a polyethersulfone membrane. Our review suggests that the method to concentrate viruses and other nanoparticles should be chosen with regard to objectives of the study and the equipment status of the laboratory.

Modern Techniques for the Isolation of Extracellular Vesicles and Viruses

Extracellular signaling is pivotal to maintain organismal homeostasis. A quickly emerging field of interest within extracellular signaling is the study of extracellular vesicles (EV), which act as messaging vehicles for nucleic acids, proteins, metabolites, lipids, etc. from donor cells to recipient cells. This transfer of biologically active material within a vesicular body is similar to the infection of a cell through a virus particle, which transfers genetic material from one cell to another to preserve an infection state, and viruses are known to modulate EV. Although considerable heterogeneity exists within EV and viruses, this review focuses on those that are small (< 200 nm in diameter) and of relatively low density (< 1.3 g/mL). A multitude of isolation methods for EV and virus particles exist. In this review, we present an update on methods for their isolation, purification, and phenotypic characterization. We hope that the information we provide will be of use to basic science and clinical investigators, as well as biotechnologists in this emerging field. Graphical Abstract.

Neuraminidase Inhibitors from the Fruiting Body of Glaziella splendens

Neuraminidase (NA) cleaves the glycosidic bond linkages of sialic acids to release the mature virions from infected cells and has been an attractive therapeutic target for anti-influenza agents. In our ongoing investigation of NA inhibitors in mushroom extracts, we found that the extract the fruiting body of Glaziella splendens potently inhibited neuraminidase. The fruiting bodies of G. splendens were extracted and partitioned successively with hexane, ethyl acetate, and butanol. The ethyl acetate soluble-layer was subjected to silica gel and Sephadex LH-20 column chromatographies, and MPLC to obtain five compounds (1-5). Their structures were determined by spectroscopic methods. NA inhibitory activity of these compounds was evaluated using NAs from recombinant rvH1N1, H3N2, and H5N1 influenza A viruses. One compound (1) was elucidated as a new azaphilone derivative, and four compounds (2-5) were identified as entonaemin A, comazaphilone D, rubiginosin A, and entonaemin B, respectively. Compounds 3 and 4 showed considerable inhibitory activity against three types of neuraminidases with the IC₅₀ values of 30.9, 41.8, and 35.7 µM for 3 and 46.5, 50.4, and 29.9 µM for 4, respectively. This study reveals that the fruiting bodies of G. splendens possess azaphilone derivatives with the NA inhibitory activity. This is the first report on the isolation of neuraminidase inhibitors from the fruiting bodies of G. splendens.

Rapid capture and detection of ostreid herpesvirus-1 from Pacific oyster Crassostrea gigas and seawater using magnetic beads

Ostreid herpesvirus-1 (OsHV-1) has been involved in mass mortality episodes of Pacific oysters Crassostrea gigas throughout the world, causing important economic losses to the aquaculture industry. In the present study, magnetic beads (MBs) coated with an anionic polymer were used to capture viable OsHV-1 from two types of naturally infected matrix: oyster homogenate and seawater. Adsorption of the virus on the MBs and characterisation of the MB-virus conjugates was demonstrated by real-time quantitative PCR (qPCR). To study the infective capacity of the captured virus, MB-virus conjugates were injected in the adductor muscle of naïve spat oysters, using oyster homogenate and seawater without MBs as positive controls, and bare MBs and sterile water as negative controls. Mortalities were induced after injection with MB-virus conjugates and in positive controls, whereas no mortalities were recorded in negative controls. Subsequent OsHV-1 DNA and RNA analysis of the oysters by qPCR and reverse transcription qPCR (RT-qPCR), respectively, confirmed that the virus was the responsible for the mortality event and the ability of the MBs to capture viable viral particles. The capture of viable OsHV-1 using MBs is a rapid and easy isolation method and a promising tool, combined with qPCR, to be applied to OsHV-1 detection in aquaculture facilities.

Capture of dengue viruses using antibody-integrated graphite-encapsulated magnetic beads produced using gas plasma technology

Despite significant advances in medicine, global health is threatened by emerging infectious diseases caused by a number of viruses. Dengue virus (DENV) is a mosquito-borne virus, which can be transmitted to humans via mosquito vectors. Previously, the Ministry of Health, Labour and Welfare in Japan reported the country's first domestically acquired case of dengue fever for almost 70 years. To address this issue, it is important to develop novel technologies for the sensitive detection of DENV. The present study reported on the development of plasma-functionalized, graphite-encapsulated magnetic nanoparticles (GrMNPs) conjugated with anti-DENV antibody for DENV capture. Radiofrequency wave-excited inductively-coupled Ar and ammonia gas plasmas were used to introduce amino groups onto the surface of the GrMNPs. The GrMNPs were then conjugated with an antibody against DENV, and the antibody-integrated magnetic beads were assessed for their ability to capture DENV. Beads incubated in a cell culture medium of DENV-infected mosquito cells were separated from the supernatant by applying a magnetic field and were then washed. The adsorption of DENV serotypes 1–4 onto the beads was confirmed using reverse transcription-polymerase chain reaction, which detected the presence of DENV genomic RNA on the GrMNPs. The methodology described in the present study, which employed the plasma-functionalization of GrMNPs to enable antibody-integration, represents a significant improvement in the detection of DENV.

Capturing and concentrating adenovirus using magnetic anionic nanobeads

We recently demonstrated how various enveloped viruses can be efficiently concentrated using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). However, the exact mechanism of interaction between the virus particles and anionic beads remains unclear. To further investigate whether these magnetic anionic beads specifically bind to the viral envelope, we examined their potential interaction with a nonenveloped virus (adenovirus). The beads were incubated with either adenovirus-infected cell culture medium or nasal aspirates from adenovirus-infected individuals and then separated from the supernatant by applying a magnetic field. After thoroughly washing the beads, adsorption of adenovirus was confirmed by a variety of techniques, including immunochromatography, polymerase chain reaction, Western blotting, and cell culture infection assays. These detection methods positively identified the hexon and penton capsid proteins of adenovirus along with the viral genome on the magnetic beads. Furthermore, various types of adenovirus including Types 5, 6, 11, 19, and 41 were captured using the magnetic bead procedure. Our bead capture method was also found to increase the sensitivity of viral detection. Adenovirus below the detectable limit for immunochromatography was efficiently concentrated using the magnetic bead procedure, allowing the virus to be successfully detected using this methodology. Moreover, these findings clearly demonstrate that a viral envelope is not required for binding to the anionic magnetic beads. Taken together, our results show that this capture procedure increases the sensitivity of detection of adenovirus and would, therefore, be a valuable tool for analyzing both clinical and experimental samples.

In situ formation of multiple stimuli-responsive poly[(methyl vinyl ether)-alt-(maleic acid)]-based supramolecular hydrogels by inclusion complexation between cyclodextrin and azobenzene

Stimuli-responsive poly[(methyl vinyl ether)-alt-(maleic acid)]-based supramolecular hydrogels were prepared in situ by inclusion complexation between cyclodextrin and azobenzene. They may have high potential in biomedical applications.

Biomarker detection of global infectious diseases based on magnetic particles

Infectious diseases affect the daily lives of millions of people all around the world, and are responsible for hundreds of thousands of deaths, mostly in the developing world. Although most of these major infectious diseases are treatable, the early identification of individuals requiring treatment remains a major issue. The incidence of these diseases would be reduced if rapid diagnostic tests were widely available at the community and primary care level in low-resource settings. Strong research efforts are thus being focused on replacing standard clinical diagnostic methods, such as the invasive detection techniques (biopsy or endoscopy) or expensive diagnostic and monitoring methods, by affordable and sensitive tests based on novel biomarkers. The development of new methods that are needed includes solid-phase separation techniques. In this context, the integration of magnetic particles within bioassays and biosensing devices is very promising since they greatly improve the performance of a biological reaction. The diagnosis of clinical samples with magnetic particles can be easily achieved without pre-enrichment, purification or pretreatment steps often required for standard methods, simplifying the analytical procedures. The biomarkers can be specifically isolated and preconcentrated from complex biological matrixes by magnetic actuation, increasing specificity and the sensitivity of the assay. This review addresses these promising features of the magnetic particles for the detection of biomarkers in emerging technologies related with infectious diseases affecting global health, such as malaria, influenza, dengue, tuberculosis or HIV.

Antibody-integrated and functionalized graphite-encapsulated magnetic beads, produced using ammonia gas plasma technology, for capturing Salmonella

Salmonella spp. is the single and most important causative agent of foodborne infections, especially involving foods such as eggs, milk and meat. To prevent infection, a reliable surveillance system is required that can quickly and sensitively detect Salmonella. Here, we describe the development of antibody-integrated magnetic beads that are functionalized by a novel strategy using ammonia gas plasma. Ammonia plasma, produced by a radio frequency (RF) power supply, was allowed to react with the surface of graphite-encapsulated magnetic beads, resulting in the introduction of amino groups. An anti-Salmonella antibody was then anchored by sulfide groups present on the protein surface to the amino groups of the magnetic beads via N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). The potential usefulness of these magnetic beads for capturing Salmonella was examined as follows. The beads were incubated with Salmonella in liquid medium and then separated from the supernatant by applying a magnetic field. After thorough washing, adsorption of Salmonella to the beads was confirmed by immunochromatography, polymerase chain reaction and a direct culture assay. Our findings indicate that the capture and concentration of Salmonella using the antibody-integrated magnetic beads was more efficient than commercial Dynabeads® anti-Salmonella, which are conventionally used for concentrating Salmonella from liquid cultures. We believe this novel bead technology will contribute to the enhanced detection of Salmonella.

N 2 gas plasma inactivates influenza virus by inducing changes in viral surface morphology, protein, and genomic RNA

We have recently treated with N₂ gas plasma and achieved inactivation of bacteria. However, the effect of N₂ gas plasma on viruses remains unclear. With the aim of developing this technique, we analyzed the virucidal effect of N₂ gas plasma on influenza virus and its influence on the viral components. We treated influenza virus particles with inert N₂ gas plasma (1.5 kpps; kilo pulses per second) produced by a short high-voltage pulse generated from a static induction thyristor power supply. A bioassay using chicken embryonated eggs demonstrated that N₂ gas plasma inactivated influenza virus in allantoic fluid within 5 min. Immunochromatography, enzyme-linked immunosorbent assay, and Coomassie brilliant blue staining showed that N₂ gas plasma treatment of influenza A and B viruses in nasal aspirates and allantoic fluids as well as purified influenza A and B viruses induced degradation of viral proteins including nucleoprotein. Analysis using the polymerase chain reaction suggested that N₂ gas plasma treatment induced changes in the viral RNA genome. Scanning electron microscopy analysis showed that aggregation and fusion of influenza viruses were induced by N₂ gas plasma treatment. We believe these biochemical changes may contribute to the inactivation of influenza viruses by N₂ gas plasma.

Isolation of infectious chikungunya virus and dengue virus using anionic polymer-coated magnetic beads

Mosquitoes-borne viruses are a major threat for human populations. Among them, chikungunya virus (CHIKV) and dengue virus (DENV) cause thousands of cases worldwide. The recent propagation of mosquito vectors competent to transmit these viruses to temperate areas increases their potential impact on susceptible human populations. The development of sensitive methods allowing the detection and isolation of infectious viruses is of crucial interest for determination of virus contamination in humans and in competent mosquito vectors. However, simple and rapid method allowing the capture of infectious CHIKV and DENV from samples with low viral titers useful for further genetic and functional characterization of circulating strains is lacking. The present study reports a fast and sensitive isolation technique based on viral particles adsorption on magnetic beads coated with anionic polymer, poly(methyl vinyl ether-maleic anhydrate) and suitable for isolation of infectious CHIKV and DENV from the four serotypes. Starting from quite reduced biological material, this method was accurate to combine with conventional detection techniques, including qRT-PCR and immunoblotting and allowed isolation of infectious particles without resorting to a step of cultivation. The use of polymer-coated magnetic beads is therefore of high interest for rapid detection and isolation of CHIKV and DENV from samples with reduced viral loads and represents an accurate approach for the surveillance of mosquito vector in area at risk for arbovirus outbreaks.

Tofuyo (fermented soybean food) extract prolongs the survival of mice infected with influenza virus

Fermented soybean, known as tofuyo, is a traditional food in Okinawa (Japan). Tofuyo extract is obtained from the supernatant of fermented soybean after homogenization, filtration and centrifugation. In this study, we analyzed the in vitro effect of tofuyo extract on influenza virus using immunochromatography of the influenza virus nucleoprotein (NP). The results showed that tofuyo extract does not have a strong inhibitory effect on NP. This finding was confirmed by an assay for virus activity using embryonated eggs. To investigate the potential anti-influenza virus activity of tofuyo in vivo, 5 nude mice (BALB/cSlc-nu/nu) were administered drinking water supplemented with tofuyo extract the day prior to intranasal inoculation with influenza virus, while the control group (5 mice) was administered tofuyo extract-free water. Control group mice (40%) were dead within 14 days, while the mice that were administered water containing tofuyo extract survived. Nutrient component analysis showed that tofuyo extract contains proteins, carbohydrates, vitamins and minerals that provide nutritional value, which may help to maintain good health.

Capture of infectious borna disease virus using anionic polymer-coated magnetic beads

Borna disease virus (BDV) is a noncytolytic, neurotrophic virus that infects a range of vertebrates, including all warm-blooded animals and possibly humans. Although BDV infections are thought to cause neurological disorders, evidence of the presence of the virus in tissues or blood of psychiatric patients is limited, possibly due to the low sensitivity of detection methods. Here, a simple method for capturing BDV has been developed using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). The beads were incubated with lysate from BDV-infected cells, then separated from the supernatant by applying a magnet field and washed. The adsorption of BDV by the beads was confirmed by reverse transcription-polymerase chain reaction and Western blotting, which indicated the presence of the phosphoprotein (P), nucleoprotein (N), and viral genome of BDV on the incubated beads. This method of capture may contribute to the improved detection of BDV.