Size distribution analysis of influenza virus particles using size exclusion chromatography

An HPLC-SEC-based rapid quantification method for vesicular stomatitis virus particles to facilitate process development

Virus particle (VP) quantification plays a pivotal role in the development of production processes of VPs for virus-based therapies. The yield based on total VP count serves as a process performance indicator for evaluating process efficiency and consistency. Here, a label-free particle quantification method for enveloped VPs was developed, with potential applications in oncolytic virotherapy, vaccine development, and gene therapy. The method comprises size-exclusion chromatography (SEC) separation using high-performance liquid chromatography (HPLC) instruments. Ultraviolet (UV) was used for particle quantification and multi-angle light scattering (MALS) for particle characterization. Consistent recoveries of over 97% in the SEC were achieved upon mobile phase screenings and addition of bovine serum albumin (BSA) as sample stabilizer. A calibration curve was generated, and the method's performance and applicability to in-process samples were characterized. The assay's repeatability variation was <1% and its intermediate precision variation was <3%. The linear range of the method spans from 7.08 × 108 to 1.72 × 1011 VP/mL, with a limit of detection (LOD) of 7.72 × 107 VP/mL and a lower limit of quantification (LLOQ) of 4.20 × 108 VP/mL. The method, characterized by its high precision, requires minimal hands-on time and provides same-day results, making it efficient for process development.

Size exclusion chromatography of biopharmaceutical products: From current practices for proteins to emerging trends for viral vectors, nucleic acids and lipid nanoparticles

The 21st century has been particularly productive for the biopharmaceutical industry, with the introduction of several classes of innovative therapeutics, such as monoclonal antibodies and related compounds, gene therapy products, and RNA-based modalities. All these new molecules are susceptible to aggregation and fragmentation, which necessitates a size variant analysis for their comprehensive characterization. Size exclusion chromatography (SEC) is one of the reference techniques that can be applied. The analytical techniques for mAbs are now well established and some of them are now emerging for the newer modalities. In this context, the objective of this review article is: i) to provide a short historical background on SEC, ii) to suggest some clear guidelines on the selection of packing material and mobile phase for successful method development in modern SEC; and iii) to highlight recent advances in SEC, such as the use of narrow-bore and micro-bore columns, ultra-wide pore columns, and low-adsorption column hardware. Some important innovations, such as recycling SEC, the coupling of SEC with mass spectrometry, and the use of alternative detectors such as charge detection mass spectrometry and mass photometry are also described. In addition, this review discusses the use of SEC in multidimensional setups and shows some of the most recent advances at the preparative scale. In the third part of the article, the possibility of SEC for the characterization of new modalities is also reviewed. The final objective of this review is to provide a clear summary of opportunities and limitations of SEC for the analysis of different biopharmaceutical products.

Adapted methods for monitoring influenza virus and respiratory syncytial virus in sludge and wastewater

Wastewater-based surveillance constitutes a valuable methodology for the continuous monitoring of viral circulation, with the capacity to function as an early warning system. It holds particular significance in scenarios where respiratory viruses exhibit overlapping clinical presentations, as occurs with SARS-CoV-2, influenza virus (IV), and respiratory syncytial virus (RSV), and allows seasonal virus outbreaks to be distinguished from COVID-19 peaks. Furthermore, sewage sludge, given it harbors concentrated human waste from a large population, serves as a substantial reservoir for pathogen detection. To effectively integrate wastewater-based epidemiology into infectious disease surveillance, the detection methods employed in wastewater samples must be adapted to the distinct characteristics of sludge matrices. In this study, we adapted and applied protocols for the detection of IV and RSV in sewage sludge, comparing their performance with the results obtained in wastewater. To assess the efficiency of these protocols, sludge and wastewater samples were spiked with IV and RSV RNA, either free or incorporated in lentiviral particles. Samples were concentrated using the aluminum hydroxide adsorption-precipitation method before viral RNA extraction. Absolute virus quantification was carried out by RT-qPCR, including an internal control to monitor potential inhibitory factors. Recovery efficiencies for both free IV and RSV RNA were 60 % in sludge, and 75 % and 71 % respectively in wastewater, whereas the values for IV and RSV RNA in lentiviral particles were 16 % and 10 % in sludge and 21 % and 17 % in wastewater respectively. Additionally, the protocol enabled the quantification of naturally occurring IV and RSV in wastewater and sludge samples collected from two wastewater treatment plants during the winter months, thus affirming the efficacy of the employed methodologies.

High yield sterile filtration process for highly concentrated lentiviral vectors

The development and manufacture of biopharmaceuticals are subject to strict regulations that specify the required minimum quality of the products. A key measure to meet these quality requirements is the integration of a sterile filtration step into the commercial manufacturing process. Whereas common procedures for most biologics exist, this is challenging for lentiviral vector (LVV) production for ex vivo gene therapy. LVVs nominal size is more than half the pore size (0.2 µm) of filters used for sterile filtration. Hence, highly concentrated virus solutions are prone to filter clogging if aggregation of viruses occurs or impurities attach to the viruses. Several filters were screened aiming to identify those which allow filtering highly concentrated stocks of LVVs of up to 1E + 9 transducing units mL-1 , which corresponds to 4.5E + 12 particles mL-1 . In addition, the effect of endonuclease treatment upstream of the purification process on filter performance was studied. In summary, three suitable filters were identified in a small-scale study (<15 mL) with virus yields >80% and the process was successfully scaled-up to a final scale of 100 mL LVV stock solution.

Fast and efficient size exclusion chromatography of adeno associated viral vectors with 2.5 micrometer particle low adsorption columns

More and more transformative gene therapies (GTx) are reaching commercialization stage and many of them use Adeno Associated Viruses (AAVs) as their vector. Being larger than therapeutic antibodies, their size variant analysis poses an analytical challenge that must be addressed to speed up the development processes. Size exclusion chromatography (SEC) can provide critical information on the quality and purity of the product, but its full potential is not yet utilized by currently applied columns that are (i) packed with relatively large particles, (ii) prepared exclusively in large formats and (iii) built using metal hardware that is prone to secondary interactions. In this paper, we investigate the use of state-of-the-art sub-3 µm particles to address existing limitations. A prototype 2.5 µm column was found to deliver superior kinetic efficiency, significant reduction in run times and increased resolution of separations. No evidence for shear or sample sieving effects were found during comparisons with conventional 5 µm columns. Moreover, use of low adsorption hardware enabled the application of a wide range of mobile phase conditions and a chance to apply a more robust platform method for several AAV serotypes. The resulting method was tested for its reproducibility as well as utility for critical quality attribute assays, including multiangle light scattering based (MALS) measurements of size and molar mass. Thus, a new tool for higher resolution, higher throughput size variant analysis of AAVs has been described.

Molecular Mechanisms behind Conformational Transitions of the Influenza Virus Hemagglutinin Membrane Anchor

Membrane fusion is a fundamental process that is exploited by enveloped viruses to enter host cells. In the case of the influenza virus, fusion is facilitated by the trimeric viral hemagglutinin protein (HA). So far, major focus has been put on its N-terminal fusion peptides, which are directly responsible for fusion initiation. A growing body of evidence points also to a significant functional role of the HA C-terminal domain, which however remains incompletely understood. Our computational study aimed to elucidate the structural and functional interdependencies within the HA C-terminal region encompassing the transmembrane domain (TMD) and the cytoplasmic tail (CT). In particular, we were interested in the conformational shift of the TMD in response to varying cholesterol concentration in the viral membrane and in its modulation by the presence of CT. Using free-energy calculations based on atomistic molecular dynamics simulations, we characterized transitions between straight and tilted metastable TMD configurations under varying conditions. We found that the presence of CT is essential for achieving a stable, highly tilted TMD configuration. As we demonstrate, such a configuration of HA membrane anchor likely supports the tilting motion of its ectodomain, which needs to be executed during membrane fusion. This finding highlights the functional role of, so far, the relatively overlooked CT region.

Evaluation of biocidal properties of biodegradable nanofiber filters and their use in face masks

Due to the recent coronavirus-2019 pandemic, several studies have emerged looking for new materials, especially with biocidal characteristics. Thus, the present research investigates the antibacterial properties of biodegradable cellulose acetate (CA) / cetylpyridinium bromide (CPB) electrospun nanofibers, their aerosol filtration, and the possible use as a filter media of surgical face masks. Then, samples of these nanofibers were produced over a nonwoven substrate, using different volumes of polymeric solution during the electrospinning process. The evaluation of the antibacterial properties of the nanofibers was performed for Escherichia coli and Staphylococcus aureus using quantitative methods. The aerosol filtration performance was evaluated in these samples for NaCl nanoparticles (from 7-300 nm) and with 8 mL min^-1 of air flow rate. The results show that the single use of the surfactant has antibacterial properties from a concentration of 39 µg mL^-1 of solution. The nanofibers presented a reduction of 100% for both bacteria. Air filtration tests showed 126.03 and 207.73 Pa cm^-² of pressure drops and 63 and 77% of aerosol filtration efficiency (FE) for samples with 0.13 and 0.15 mL, respectively. Regarding the nanofiber produced with 0.35 mL, the value obtained was 115.13 ± 33.64 Pa cm^-2 and 3.15% of particle penetration. These breathability values are higher than those required for the surgical face mask standard, indicating that improvements in the porosity and thickness are necessary to meet the Brazilian requirements. However, the nanofibers could be applied as filter media for indoor air conditioning systems due to their FE and biocidal properties.

Isolation and characterization of Newcastle disease virus from biological fluids using column chromatography

Newcastle disease virus (NDV), belonging to the species avian orthoavulavirus 1, genus Orthoavulavirus, and family Paramyxoviridae, is responsible for Newcastle disease in poultry and other avian species. It has shown significant potential as an oncolytic virus and as a vector for vaccine delivery. NDV from infected biological serum is usually isolated or purified using density gradient ultracentrifugation. However, it has many disadvantages, including the fact that it is time consuming and can process only a limited quantity of sample at one time. In our study, native agarose gel electrophoresis and dynamic light scattering (DLS) analysis showed that NDV carried a net negative surface charge. Thus, we purified the virus using a HiTrap Q Sepharose Fast Flow anion exchange column with salt elution. Hemagglutination assay and plaque assay showed that the procedure yielded high-purity NDV particles with a recovery of more than 80%, and the process was fast and simple. The purity of the virus was confirmed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. The hydrodynamic volume and 'dry state' diameter of the purified NDV were analyzed using dynamic light scattering and transmission electron microscopy and were to be in the range of 200-300 nm. The viruses did not exhibit any deviation from their known physical properties. The genome of the virus was also detected by amplifying a 423-bp region using reverse transcription-polymerase chain reaction. Our study confirmed that NDV could be effectively purified using an anion exchange column. In addition, the procedure could be easily upscaled or downscaled based on the experimental requirements.

Quantification methods for viruses and virus-like particles applied in biopharmaceutical production processes

INTRODUCTION

Effective cell-based production processes of virus particles are the foundation for the global availability of classical vaccines, gene therapeutic vectors, and viral oncolytic treatments. Their production is subject to regulatory standards ensuring the safety and efficacy of the pharmaceutical product. Process analytics must be fast and reliable to provide an efficient process development and a robust process control during production. Additionally, for the product release, the drug compound and the contaminants must be quantified by assays specified by regulatory authorities.

AREAS COVERED

This review summarizes analytical methods suitable for the quantification of viruses or virus-like particles. The different techniques are grouped by the analytical question that may be addressed. Accordingly, methods focus on the infectivity of the drug component on the one hand, and on particle counting and the quantification of viral elements on the other hand. The different techniques are compared regarding their advantages, drawbacks, required assay time, and sample throughput.

EXPERT OPINION

Among the technologies summarized, a tendency toward fast methods, allowing a high throughput and a wide applicability, can be foreseen. Driving forces for this progress are miniaturization and automation, and the continuous enhancement of process-relevant databases for a successful future process control.

An overview of influenza A virus genes, protein functions, and replication cycle highlighting important updates

The recent research findings on influenza A virus (IAV) genome biology prompted us to present a comprehensive overview of IAV genes, protein functions, and replication cycle. The eight gene segments of the IAV genome encode 17 proteins, each having unique functions contributing to virus fitness in the host. The polymerase genes are essential determinants of IAV pathogenicity and virulence; however, other viral components also play crucial roles in the IAV replication, transmission, and adaptation. Specific adaptive mutations within polymerase (PB2, PB1, and PA) and glycoprotein-hemagglutinin (HA) and neuraminidase (NA) genes, may facilitate interspecies transmission and adaptation of IAV. The HA-NA interplay is essential for establishing the IAV infection; the low pH triggers the inactivation of HA-receptor binding, leading to significantly lower NA activities, indicating that the enzymatic function of NA is dependent on HA binding. While the HA and NA glycoproteins are required to initiate infection, M1, M2, NS1, and NEP proteins are essential for cytoplasmic trafficking of viral ribonucleoproteins (vRNPs) and the assembly of the IAV virions. The mechanisms that enable IAV to exploit the host cell resources to advance the infection are discussed. A comprehensive understanding of IAV genome biology is essential for developing antivirals to combat the IAV disease burden.

Sensitivity Characterization of Multi-Band THz Metamaterial Sensor for Possible Virus Detection

The recent COVID-19 pandemic has shown that there is a substantial need for high-precision reliable diagnostic tests able to detect extremely low virus concentrations nearly instantaneously. Since conventional methods are fairly limited, there is a need for an alternative method such as THz spectroscopy with the utilization of THz metamaterials. This paper proposes a method for sensitivity characterization, which is demonstrated on two chosen multi-band THz metamaterial sensors and samples of three different subtypes of the influenza A virus. Sensor models have been simulated in WIPL-D software in order to analyze their sensitivity both graphically and numerically around all resonant peaks in the presence of virus samples. The sensor with a sandwiched structure is shown to be more suitable for detecting extremely thin virus layers. The distribution of the electric field for this sensor suggests a possibility of controlling the two resonant modes independently. The sensor with cross-shaped patches achieves significantly better Q-factors and refractive sensitivities for both resonant peaks. The reasoning can be found in the wave–sample interaction enhancement due to the better electromagnetic field confinement. A high Q-factor of around 400 at the second resonant frequency makes the sensor with cross-shaped patches a promising candidate for potential applications in THz sensing.

Functional Microfiber Nonwoven Fabric with Sialic Acid-Immobilized Polymer Brush for Capturing Lectin in Aerosol

The influenza virus has been known as a representative infectious virus that harms human health from the past to the present day. We have promoted the development of a novel adsorbent capable of adsorbing influenza viruses in the form of aerosols in the air. In this study, to develop a material to adsorb the influenza virus, a functional group was introduced into a microfiber nonwoven fabric (MNWF) manufactured through radiation-induced graft polymerization (RIGP), and sialic acid was immobilized to mimic the sugar chain cluster effect. The functional group was used by coupling disodium iminodiacetate monohydrate (IDA) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC), and N-acetylneuraminic acid (NANA) was selected for sialic acid. IDA-EDC was introduced into GMA MNWF with an average molar conversion of 47%. For NANA MNWF with a degree of grafting (dg) of 87% introduced with sialic acid, 118.2 of 200 µg of aerosolized lectin was adsorbed, confirming that the maximum adsorption amount was 59.1%. In NANA MNWF of 100% or more dg, a tendency to decrease the amount of lectin adsorption was observed compared to NANA MNWF of 80–100% dg.

Graphene and carbon nanotubes interfaced electrochemical nanobiosensors for the detection of SARS-CoV-2 (COVID-19) and other respiratory viral infections: A review

Recent COVID-19 pandemic has claimed millions of lives due to lack of a rapid diagnostic tool. Global scientific community is now making joint efforts on developing rapid and accurate diagnostic tools for early detection of viral infections to preventing future outbreaks. Conventional diagnostic methods for virus detection are expensive and time consuming. There is an immediate requirement for a sensitive, reliable, rapid and easy-to-use Point-of-Care (PoC) diagnostic technology. Electrochemical biosensors have the potential to fulfill these requirements, but they are less sensitive for sensing viruses/viral infections. However, sensitivity and performance of these electrochemical platforms can be improved by integrating carbon nanostructure, such as graphene and carbon nanotubes (CNTs). These nanostructures offer excellent electrical property, biocompatibility, chemical stability, mechanical strength and, large surface area that are most desired in developing PoC diagnostic tools for detecting viral infections with speed, sensitivity, and cost-effectiveness. This review summarizes recent advancements made toward integrating graphene/CNTs nanostructures and their surface modifications useful for developing new generation of electrochemical nanobiosensors for detecting viral infections. The review also provides prospects and considerations for extending the graphene/CNTs based electrochemical transducers into portable and wearable PoC tools that can be useful in preventing future outbreaks and pandemics.

An Overview of Influenza Viruses and Vaccines

Influenza remains one of the major public health concerns because it causes annual epidemics and can potentially instigate a global pandemic. Numerous countermeasures, including vaccines and antiviral treatments, are in use against seasonal influenza infection; however, their effectiveness has always been discussed due to the ongoing resistance to antivirals and relatively low and unpredictable efficiency of influenza vaccines compared to other vaccines. The growing interest in vaccines as a promising approach to prevent and control influenza may provide alternative vaccine development options with potentially increased efficiency. In addition to currently available inactivated, live-attenuated, and recombinant influenza vaccines on the market, novel platforms such as virus-like particles (VLPs) and nanoparticles, and new vaccine formulations are presently being explored. These platforms provide the opportunity to design influenza vaccines with improved properties to maximize quality, efficacy, and safety. The influenza vaccine manufacturing process is also moving forward with advancements relating to egg- and cell-based production, purification processes, and studies into the physicochemical attributes and vaccine degradation pathways. These will contribute to the design of more stable, optimized vaccine formulations guided by contemporary analytical testing methods and via the implementation of the latest advances in the field.

Ultrasonic scaling in COVID-era dentistry: A quantitative assessment of aerosol spread during simulated and clinical ultrasonic scaling procedures

Objective

Healthcare agencies recommend limited use of aerosol‐generating procedures to mitigate disease (COVID‐19) transmission. However, total dispersion patterns of aerosols, particularly respirable droplets, via dental ultrasonic units is unclear. The purpose of this study was to characterize and map total spatter, droplet and aerosol dispersion during ultrasonic scaling in simulated and clinical contexts.

Methods

Ultrasonic scaling was performed on dental simulation units using methylene blue dye‐stained water. All resultant stain profiles were photoanalysed to calculate droplet size and travel distance/direction. Airborne particle concentrations were also documented 0–1.2 m (0–4ft.) and 1.2–2.4 m (4–8ft.) from patients during in vivo ultrasonic scaling with a saliva ejector.

Results

Stain profiles showed droplets between 25 and 50µm in diameter were most common, with smaller droplets closer to the mouth. In‐vivo particle concentrations were uniformly low. The smallest (<1 µm, PM1) and largest (>10 µm, PM10+) particles were most common, especially within 1.2 m (4ft.) of the patient. Respirable particles (PM2.5) were uncommon.

Conclusions

Tests showed the highest concentration of small droplets in zones nearest the patient. While uncommon, particles were detected up to 2.4 m (8ft.) away. Furthermore, observed particle sizes were consistent with those that can carry infectious agents. Efforts to mitigate the spread of inhalable aerosols should emphasize proximate regions nearest the procedure, including personal protective equipment and the use of evacuation devices.

Pollen antigens and atmospheric circulation driven seasonal respiratory viral outbreak and its implication to the Covid-19 pandemic

The patterns of respiratory virus illness are expressed differently between temperate and tropical climates. Tropical outbreaks often peak in wet seasons. Temperate outbreaks typically peak during the winter. The prevailing causal hypotheses focus on sunlight, temperature and humidity variations. Yet no consistent factors have been identified to sufficiently explain seasonal virus emergence and decline at any latitude. Here we demonstrate close connections among global-scale atmospheric circulations, IgE antibody enhancement through seasonal pollen inhalation, and respiratory virus patterns at any populated latitude, with a focus on the US. Pollens emerge each Spring, and the renewed IgE titers in the population are argued to terminate each winter peak of respiratory illness. Globally circulated airborne viruses are postulated to subsequently deposit across the Southern US during lower zonal geostrophic winds each late Summer. This seasonally refreshed viral load is postulated to trigger a new influenza outbreak, once the existing IgE antibodies diminish to a critical value each Fall. Our study offers a new and consistent explanation for the seasonal diminishment of respiratory viral illnesses in temperate climates, the subdued seasonal signature in the tropics, the annually circulated virus phenotypes, and the northerly migration of influenza across the US every year. Our integrated geospatial and IgE hypothesis provides a new perspective for prediction, mitigation and prevention of the outbreak and spread of seasonal respiratory viruses including Covid-19 pandemic.

Towards a Quantitative Single Particle Characterization by Super Resolution Microscopy: From Virus Structures to Antivirals Design

In the last year the COVID19 pandemic clearly illustrated the potential threat that viruses pose to our society. The characterization of viral structures and the identification of key proteins involved in each step of the cycle of infection are crucial to develop treatments. However, the small size of viruses, invisible under conventional fluorescence microscopy, make it difficult to study the organization of protein clusters within the viral particle. The applications of super-resolution microscopy have skyrocketed in the last years, converting this group into one of the leading techniques to characterize viruses and study the viral infection in cells, breaking the diffraction limit by achieving resolutions up to 10 nm using conventional probes such as fluorescent dyes and proteins. There are several super-resolution methods available and the selection of the right one it is crucial to study in detail all the steps involved in the viral infection, quantifying and creating models of infection for relevant viruses such as HIV-1, Influenza, herpesvirus or SARS-CoV-1. Here we review the use of super-resolution microscopy (SRM) to study all steps involved in the viral infection and antiviral design. In light of the threat of new viruses, these studies could inspire future assays to unveil the viral mechanism of emerging viruses and further develop successful antivirals against them.

Patterns of virus growth across the diversity of life

Although viruses in their natural habitats add up to less than 10% of the biomass, they contribute more than 90% of the genome sequences [1]. These viral sequences or 'viromes' encode viruses that populate the Earth's oceans [2, 3] and terrestrial environments [4, 5], where their infections impact life across diverse ecological niches and scales [6, 7], including humans [8-10]. Most viruses have yet to be isolated and cultured [11-13], and surprisingly few efforts have explored what analysis of available data might reveal about their nature. Here, we compiled and analyzed seven decades of one-step growth and other data for viruses from six major families, including their infections of archaeal, bacterial and eukaryotic hosts [14-191]. We found that the use of host cell biomass for virus production was highest for archaea at 10%, followed by bacteria at 1% and eukarya at 0.01%, highlighting the degree to which viruses of archaea and bacteria exploit their host cells. For individual host cells, the yield of virus progeny spanned a relatively narrow range (10-1000 infectious particles per cell) compared with the million-fold difference in size between the smallest and largest cells. Furthermore, healthy and infected host cells were remarkably similar in the time they needed to multiply themselves or their virus progeny. Specifically, the doubling time of healthy cells and the delay time for virus release from infected cells were not only correlated (r = 0.71, p < 10-10, n = 101); they also spanned the same range from tens of minutes to about a week. These results have implications for better understanding the growth, spread and persistence of viruses in complex natural habitats that abound with diverse hosts, including humans and their associated microbes.

The Role of Bcl-xL Protein in Viral Infections

Bcl-xL represents a family of proteins responsible for the regulation of the intrinsic apoptosis pathway. Due to its anti-apoptotic activity, Bcl-xL co-determines the viability of various virally infected cells. Their survival may determine the effectiveness of viral replication and spread, dynamics of systemic infection, and viral pathogenesis. In this paper, we have reviewed the role of Bcl-xL in the context of host infection by eight different RNA and DNA viruses: hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), influenza A virus (IAV), Epstein-Barr virus (EBV), human T-lymphotropic virus type-1 (HTLV-1), Maraba virus (MRBV), Schmallenberg virus (SBV) and coronavirus (CoV). We have described an influence of viral infection on the intracellular level of Bcl-xL and discussed the impact of Bcl-xL-dependent cell survival control on infection-accompanying pathogenic events such as tissue damage or oncogenesis. We have also presented anti-viral treatment strategies based on the pharmacological regulation of Bcl-xL expression or activity.

Comprehensive characterization and quantification of adeno associated vectors by size exclusion chromatography and multi angle light scattering

Adeno associated virus (AAV) capsids are a leading modality for in vivo gene delivery. Complete and precise characterization of capsid particles, including capsid and vector genome concentration, is necessary to safely and efficaciously dose patients. Size exclusion chromatography (SEC) coupled to multiangle light scattering (MALS) offers a straightforward approach to comprehensively characterize AAV capsids. The current study demonstrates that this method provides detailed AAV characterization information, including but not limited to aggregation profile, size-distribution, capsid content, capsid molar mass, encapsidated DNA molar mass, and total capsid and vector genome titer. Currently, multiple techniques are required to generate this information, with varying accuracy and precision. In the current study, a new series of equations for SEC-MALS are used in tandem with intrinsic properties of the capsids and encapsidated DNA to quantify multiple physical AAV attributes in one 20-min run with minimal sample manipulation, high accuracy, and high precision. These novel applications designate this well-established method as a powerful tool for product development and process analytics in future gene therapy programs.

The energy and environmental footprints of COVID-19 fighting measures - PPE, disinfection, supply chains

The still escalating COVID-19 pandemic also has a substantial impact on energy structure, requirements and related emissions. The consumption is unavoidable and receives a lower priority in the critical situation. However, as the pandemic continues, the impacts on energy and environment should be assessed and possibly reduced. This study aims to provide an overview of invested energy sources and environmental footprints in fighting the COVID-19. The required energy and resources consumption of Personal Protection Equipment (PPE) and testing kits have been discussed. The protecting efficiency returned on environmental footprint invested for masks has been further explored. The main observation pinpointed is that with a proper design standard, material selection and user guideline, reusable PPE could be an effective option with lower energy consumption/environmental footprint. Additional escalated energy consumption for aseptic and disinfection has been assessed. This includes the energy stemming from emergency and later managed supply chains. The outcomes emphasised that diversifying solutions to achieve the needed objective is a vital strategy to improve the susceptibility and provide higher flexibility in minimising the environmental footprints. However, more comprehensive research proof for the alternative solution (e.g. reusable option) towards low energy consumption without compromise on the effectiveness should be offered and advocated.

Characterization and stabilization in process development and product formulation for super large proteinaceous particles

Super large proteinaceous particles (SLPPs) such as virus, virus like particles, and extracellular vesicles have successful and promising applications in vaccination, gene therapy, and cancer treatment. The unstable nature, the complex particulate structure and composition are challenges for their manufacturing and applications. Rational design of the processing should be built on the basis of fully understanding the characteristics of these bio-particles. This review highlights useful analytical techniques for characterization and stabilization of SLPPs in the process development and product formulations, including high performance size exclusion chromatography, multi-angle laser light scattering, asymmetrical flow field-flow fractionation, nanoparticle tracking analysis, CZE, differential scanning calorimetry, differential scanning fluorescence, isothermal titration calorimetry , and dual polarization interferometry. These advanced analytical techniques will be helpful in obtaining deep insight into the mechanism related to denaturation of SLPPs, and more importantly, in seeking solutions to preserve their biological functions against deactivation or denaturation. Combination of different physicochemical techniques, and correlation with in vitro or in vivo biological activity analyses, are considered to be the future trend of development in order to guarantee a high quality, safety, and efficacy of SLPPs.

Recent advances on protein separation and purification methods

Protein, as the material basis of vita, is the crucial undertaker of life activities, which constitutes the framework and main substance of human tissues and organs, and takes part in various forms of life activities in organisms. Separating proteins from biomaterials and studying their structures and functions are of great significance for understanding the law of life activities and clarifying the essence of life phenomena. Therefore, scientists have proposed the new concept of proteomics, in which protein separation technology plays a momentous role. It has been diffusely used in the food industry, agricultural biological research, drug development, disease mechanism, plant stress mechanism, and marine environment research. In this paper, combined with the recent research situation, the progress of protein separation technology was reviewed from the aspects of extraction, precipitation, membrane separation, chromatography, electrophoresis, molecular imprinting, microfluidic chip and so on.

Adjuvantation of an Influenza Hemagglutinin Antigen with TLR4 and NOD2 Agonists Encapsulated in Poly(D,L-Lactide-Co-Glycolide) Nanoparticles Enhances Immunogenicity and Protection against Lethal Influenza Virus Infection in Mice

Along with their excellent safety profiles, subunit vaccines are typically characterized by much weaker immunogenicity and protection efficacy compared to whole-pathogen vaccines. Here, we present an approach aimed at bridging this disadvantage that is based on synergistic collaboration between pattern-recognition receptors (PRRs) belonging to different families. We prepared a model subunit vaccine formulation using an influenza hemagglutinin antigen incorporated into poly-(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles adjuvanted with monophosphoryl lipid A (TLR4 agonist) and muramyl dipeptide (NOD2 agonist). The efficacy studies were conducted in comparison to control vaccine formulations containing individual PRR agonists. We show that the complex adjuvant based on TLR4 and NOD2 agonists potentiates proinflammatory cell responses (measured by activity of transcription factors and cytokine production both in vitro and in vivo) and enhances the phagocytosis of vaccine particles up to comparable levels of influenza virus uptake. Finally, mice immunized with vaccine nanoparticles containing both PRR agonists exhibited enhanced humoral (IgG, hemagglutination-inhibition antibody titers) and cellular (percentage of proliferating CD4+ T-cells, production of IFNɣ) immunity, leading to increased resistance to lethal influenza challenge. These results support the idea that complex adjuvants stimulating different PRRs may present a better alternative to individual PAMP-based adjuvants and could further narrow the gap between the efficacy of subunit versus whole-pathogen vaccines.

Society of Robotic Surgery review: recommendations regarding the risk of COVID-19 transmission during minimally invasive surgery

Objectives

To determine the risk of COVID‐19 transmission during minimally invasive surgical (MIS) procedures

Methods

Surgical society statements regarding the risk of COVID transmission during MIS procedures were reviewed. In addition, the available literature on COVID‐19 and other viral transmission in CO2 pneumoperitoneum, as well as the presence of virus in the plume created by electrocautery during MIS was reviewed. The society recommendations were compared to the available literature on the topic to create our review and recommendations to mitigate COVID‐19 transmission.

Results

The recommendations promulgated by various surgical societies evolved over time as more information became available on COVID‐19 transmission. Review of the available literature on the presence of COVID‐19 in CO2 pneumoperitoneum was inconclusive. There is no clear evidence of the presence of COVID‐19 in plume created by electrocautery. Technologies to reduce CO2 pneumoperitoneum release into the operating room as well as filter viral particles are available and should reduce the exposure risk to operating room personnel.

Conclusion

There is no clear evidence of COVID‐19 virus in the CO2 used during MIS procedures or in the plume created by electrocautery. Until the presence or absence of COVID‐19 viral particles has been clearly established, measures to mitigate CO2 and surgical cautery plume release into the operating room should be performed. Further study on the presence of COVID‐19 in MIS pneumoperitoneum and cautery plume is needed.

Considerations for the otolaryngologist in the era of COVID-19: a review of the literature

PURPOSE OF REVIEW

The SARS-CoV-2 coronavirus pandemic, referred to as COVID-19, has spread throughout the globe since its first case in China in December 2019, leaving a significant number of people infected and clinically ill. The purpose of this review is to provide the current known clinical characteristics of and management for COVID-19 as it relates to otolaryngology.

RECENT FINDINGS

COVID-19 is a highly transmissible respiratory disease with common presenting symptoms of fever, cough, and fatigue. In the absence of available vaccines or antiviral therapies, symptomatic and respiratory support is the current standard of therapy. Measures to prevent further transmission have been enacted globally including social distancing and cancellation of public events. Given elevated viral load in the upper aerodigestive tract, extra precautions in patients with otolaryngology needs have been recommended for protection of both healthcare workers and patients.

SUMMARY

Otolaryngologists face unique risk from COVID-19. Maintaining appropriate preventive health measures and remaining updated on institutional clinical guidelines is paramount for both caretaker safety and patient care.

Interference chromatography: a novel approach to optimizing chromatographic selectivity and separation performance for virus purification

Background

Oncolytic viruses are playing an increasingly important role in cancer immunotherapy applications. Given the preclinical and clinical efficacy of these virus-based therapeutics, there is a need for fast, simple, and inexpensive downstream processing methodologies to purify biologically active viral agents that meet the increasingly higher safety standards stipulated by regulatory authorities like the Food and Drug Administration and the European Agency for the Evaluation of Medicinal Products. However, the production of virus materials for clinical dosing of oncolytic virotherapies is currently limited—in quantity, quality, and timeliness—by current purification technologies. Adsorption of virus particles to solid phases provides a convenient and practical choice for large-scale fractionation and recovery of viruses from cell and media contaminants. Indeed, chromatography has been deemed the most promising technology for large-scale purification of viruses for biomedical applications. The implementation of new chromatography media has improved process performance, but low yields and long processing times required to reach the desired purity are still limiting.

Results

Here we report the development of an interference chromatography-based process for purifying high titer, clinical grade oncolytic Newcastle disease virus using NatriFlo® HD-Q membrane technology. This novel approach to optimizing chromatographic performance utilizes differences in molecular bonding interactions to achieve high purity in a single ion exchange step.

Conclusions

When used in conjunction with membrane chromatography, this high yield method based on interference chromatography has the potential to deliver efficient, scalable processes to enable viable production of oncolytic virotherapies.

Dynamic Light Scattering (DLS)

Focus a laser on dissolved particles and analyze the scattered light to reveal their size. This well established principle is used in dynamic light scattering (DLS), or also called photon-correlation spectroscopy, which is a widely popular and highly adaptable analytical method applied in different fields of life and material sciences, as well as in industrial quality control processes.

Development of a New Tandem Ion Exchange and Size Exclusion Chromatography Method To Monitor Vaccine Particle Titer in Cell Culture Media

A new tandem chromatography method was developed to directly measure the titers of various vaccine candidate molecules in cell culture without a prior purification step. The method utilized a strong anion exchange chromatography (IEC) column in tandem with a size exclusion chromatography (SEC) column to efficiently separate the nanoparticle and virus-like particle (VLP) vaccine molecules from host cell proteins and other components in the cell culture media. The dual (charge and hydrodynamic size) separation mode was deemed necessary to achieve good separation of the vaccine product for quantitation. The method development and quality assessment illustrated herein was focused on the influenza vaccine candidate H1ssF, a hemagglutinin (group 1) stabilized stem molecule fused to ferritin to form nanoparticles. This newly established method was then successfully applied to several vaccine candidate developmental projects, such as the hemagglutinin-ferritin (HAF) nanoparticle and encephalitic alphavirus VLP-based vaccines. This IEC-SEC strategy was established as a platform approach for direct titer measurement of novel vaccine molecules in cell culture.

Optical nondestructive dynamic measurements of wafer-scale encapsulated nanofluidic channels

Nanofluidic channels are of great interest for DNA sequencing, chromatography, and drug delivery. However, metrology of embedded or sealed nanochannels and measurement of their fill-state have remained extremely challenging. Existing techniques have been restricted to optical microscopy, which suffers from insufficient resolution, or scanning electron microscopy, which cannot measure sealed or embedded channels without cleaving the sample. Here, we demonstrate a novel method for accurately extracting nanochannel cross-sectional dimensions and monitoring fluid filling, utilizing spectroscopic ellipsometric scatterometry, combined with rigorous electromagnetic simulations. Our technique is capable of measuring channel dimensions with better than 5-nm accuracy and assessing channel filling within seconds. The developed technique is, thus, well suited for both process monitoring of channel fabrication as well as for studying complex phenomena of fluid flow through nanochannel structures.

Viral Aggregation: Impact on Virus Behavior in the Environment

Aggregates of viruses can have a significant impact on quantification and behavior of viruses in the environment. Viral aggregates may be formed in numerous ways. Viruses may form crystal like structures and aggregates in the host cell during replication or may form due to changes in environmental conditions after virus particles are released from the host cells. Aggregates tend to form near the isoelectric point of the virus, under the influence of certain salts and salt concentrations in solution, cationic polymers, and suspended organic matter. The given conditions under which aggregates form in the environment are highly dependent on the type of virus, type of salts in solution (cation, anion. monovalent, divalent) and pH. However, virus type greatly influences the conditions when aggregation/disaggregation will occur, making predictions difficult under any given set of water quality conditions. Most studies have shown that viral aggregates increase the survival of viruses in the environment and resistance to disinfectants, especially with more reactive disinfectants. The presence of viral aggregates may also result in overestimation of removal by filtration processes. Virus aggregation-disaggregation is a complex process and predicting the behavior of any individual virus is difficult under a given set of environmental circumstances without actual experimental data.

Specific ion effects on the particle size distributions of cell culture-derived influenza A virus particles within the Hofmeister series

Virus particle (VP) aggregation can have serious implications on clinical safety and efficacy of virus-based therapeutics. Typically, VP are suspended in buffers to establish defined product properties. Salts used to achieve these properties show specific effects in chemical and biological systems in a reoccurring trend known as Hofmeister series (HS). Hofmeister series effects are ubiquitous and can affect colloidal particle systems. In this study, influences of different ions (anions: SO4 2-, HPO4 2-, Cl-, Br-, NO3 -, I-; cations: K+, Na+, Li+, Mg2+, Ca2+) on particle size distributions of cell culture-derived influenza VP were investigated. For the experimental setup, influenza virus A/Puerto Rico/8/34 (H1N1) VP produced in adherent and suspension Madin Darby canine kidney cells were used. Inactivated and concentrated virus harvests were dialyzed against buffers containing the ions of interest, followed by differential centrifugal sedimentation to measure particle size distributions. VP from both cell lines showed no aggregation over a wide range of buffers containing different salts in concentrations ≥60 mM. However, when dialyzed to low salt or Ca2+ buffers, VP produced in adherent cells showed increased aggregation compared to VP produced in suspension cells. Additionally, changes in VP diameters depending on specific ion concentrations were observed that partially reflected the HS trend.