Bacteriophage MS2 Research Articles

Selection of a SARS-CoV-2 Surrogate for Use in Surface Disinfection Efficacy Studies with Chlorine and Antimicrobial Surfaces.

Initial recommendations for surface disinfection to prevent SARS-CoV-2 transmission were developed using previous evidence from potential surrogates. To the best of our knowledge, no appropriate surrogate for SARS-CoV-2 has been identified or confirmed for chlorine and antimicrobial surface disinfection. We completed a study to evaluate the efficacy of two hypothesized antimicrobial surfaces, and four chlorine solutions on nonporous and porous surfaces, against SARS-CoV-2 and three potential SARS-CoV-2 surrogates [coronavirus mouse hepatitis virus (MHV) and bacteriophages Phi6 and MS2], to identify a BSL-1 or BSL-2 virus to use in future studies. We found SARS-CoV-2 can be reduced >4 log10 on porous and nonporous surfaces within 30 s upon exposure to 0.5% NaOCl. The results indicate coronavirus MHV-GFP is inactivated faster than SARS-CoV-2 (MHV-GFP ≥ 6.08 log10; SARS-CoV-2 = 0.66 log10 at 30 s with 0.05% NaOCl on steel) and MS2 is inactivated more slowly. Phi6 is inactivated like SARS-CoV-2, and we propose Phi6 as a slightly conservative surrogate for SARS-CoV-2 chlorine disinfection. Additionally, disinfection of bacteriophages on wood was challenging, and exposure to antimicrobial surfaces had no disinfection efficacy as tested. We recommend using 0.5% chlorine on surfaces for a minimum of 30 s of contact to disinfect SARS-CoV-2 and recommend additional research on Phi6 disinfection with varied surfaces and conditions.

Characterizing hydrogen bonds in intact RNA from MS2 bacteriophage using magic angle spinning NMR

RNA is a polymer with pivotal functions in many biological processes. RNA structure determination is thus a vital step toward understanding its function. The secondary structure of RNA is stabilized by hydrogen bonds formed between nucleotide basepairs, and it defines the positions and shapes of functional stem-loops, internal loops, bulges, and other functional and structural elements. In this work, we present a methodology for studying large intact RNA biomolecules using homonuclear 15N solid-state NMR spectroscopy. We show that proton-driven spin-diffusion experiments with long mixing times, up to 16 s, improved by the incorporation of multiple rotor-synchronous 1H inversion pulses (termed radio-frequency dipolar recoupling pulses), reveal key hydrogen-bond contacts. In the full-length RNA isolated from MS2 phage, we observed strong and dominant contributions of guanine-cytosine Watson-Crick basepairs, and beyond these common interactions, we observe a significant contribution of the guanine-uracil wobble basepairs. Moreover, we can differentiate basepaired and non-basepaired nitrogen atoms. Using the improved technique facilitates characterization of hydrogen-bond types in intact large-scale RNA using solid-state NMR. It can be highly useful to guide secondary structure prediction techniques and possibly structure determination methods.

Ozone: A Novel Sterilizer for Personal Protective Equipment.

Objective: Personal protective equipment (PPE) is urgently sought during public health crises. It is necessary for the safety of both the patient and the healthcare professional. Yet during the recent COVID-19 pandemic, PPE scarcity in many countries, including the United States, has impacted the level of care for patients and the safety of healthcare personnel. Additionally, the implementation of mandatory mask mandates for the general public in many countries forced individuals to either reuse PPE, which can contribute to poor hygiene, or buy PPE in bulk and thereby contribute to the scarcity of PPE. In this study, we investigate the possibility of using a cost-effective ozone sterilization unit on contaminated N95 masks as an alternative to current sterilization methods.Method: This protocol examined ozone’s ability to decontaminate N95 mask fabric that was exposed to a surrogate virus (Escherichia coli bacteriophage MS2). Once the sterilization unit achieves an ozone concentration of ~30 ppm, a 60-minute or 120-minute sterilization cycle commences. Following the sterilization cycle, we investigated the amount of viable virus on the slide using a viral plaque assay and compared it to a non-sterilized, control slide.Furthermore, we carried out trials to investigate the safety of an ozone sterilization device, by measuring the levels of ozone exposure that individuals may experience when operating the sterilization unit post-cycle.Results: We showed that a 120-minute sterilization cycle at ~30 ppm achieves a 3-log reduction in viral activity, thereby complying with industry and U.S. Food and Drug Administration (FDA) standards. Further, we demonstrated that when following our protocol, the ozone exposure levels for a simple sterilization unit to be used at home complied with federal and industry standards.Conclusion: Ozone may have the potential to decontaminate masks and other PPE.

Application of zinc oxide nano particles using polymeric binders on cotton fabric

Purpose The durability of antimicrobial agents and its effectiveness is the most important factor for consumer usage. One important class of antimicrobial agents are inorganic metals and their metal oxides which can be prepared into nanoparticles and can be imparted to enhance the antimicrobial properties. The purpose of this paper is to investigate the effect of three different polymeric binders during the application of zinc oxide (ZnO) nanoparticles on the antimicrobial and performance properties of the finished fabric. Design/methodology/approach In this study, ZnO nanoparticles were prepared by a wet chemical method. The nano-particles size distributions was determined using Nanoplus Dynamic Light Scattering particle size distribution analyzer and concentration of nano ZnO 0.1% (w/v) was applied with 2% (w/v) polymeric binders, namely, polyvinyl alcohol (PVA), polyurethane (PU) and butyl acrylic (BA) on cotton fabric by pad dry cure method. The treated samples were tested for physical properties such as tearing strength, tensile strength, crease recovery and air permeability and antimicrobial properties using test method American Association of Textile Chemists and Colorists (AATCC) 100. Further, the content of zinc in the treated samples was determined by the atomic absorption method. The treated fabric was analyzed using fourier transform infrared spectroscopy and scanning electron microscopic and also tested for cytotoxicity as per International Organization for Standardization 10993. Findings The results indicated that the type of polymeric binders did not show any influence on the uptake of the zinc content. All treated samples showed positive results >99% with regard to antibacterial property. However, the polymeric treated samples showed a difference in physical properties. The ZnO nano-finish reduced the tensile strength and tearing strength of the fabrics. The difference in crease recovery for samples ZnO/PVA and ZnO/PU was not much except for ZnO/BA where it increased by 38%. The air permeability decreased after application for all treated samples, the lowest among treated samples was in ZnO/PU fabric. Further, ZnO/PVA finished fabric was found to retain antibacterial property up to 50 washes and was effective against MS2 Bacteriophage as a surrogate virus when analyzed as per AATCC 100–2012 test method, and therefore can be potentially used as health-care apparel such as doctors coat and scrub suits. Originality/value The outcome of this research is in its contribution to the field of reusable textiles. It highlights the use of nanotechnology to design and develop cotton fabrics for antimicrobial properties which has the potential of preventing the growth of harmful bacteria. The study brings forth the use of ZnO nanoparticles mixed with PVA binder on 100% cotton fabrics which exhibits antibacterial and antiviral properties with adequate wash durability. Currently, there is a high demand of effective durable textiles with barrier properties and the present study provides a promising solution to provide reusable textiles with a greater level of protection.

Virus Removal and Inactivation Mechanisms during Iron Electrocoagulation: Capsid and Genome Damages and Electro-Fenton Reactions.

Virus destabilization and inactivation are critical considerations in providing safe drinking water. We demonstrate that iron electrocoagulation simultaneously removed (via sweep flocculation) and inactivated a non-enveloped virus surrogate (MS2 bacteriophage) under slightly acidic conditions, resulting in highly effective virus control (e.g., 5-logs at 20 mg Fe/L and pH 6.4 in 30 min). Electrocoagulation simultaneously generated H2O2 and Fe(II) that can potentially trigger electro-Fenton reactions to produce reactive oxygen species such as •OH and high valent oxoiron(IV) that are capable of inactivating viruses. To date, viral attenuation during water treatment has been largely probed by evaluating infective virions (as plaque forming units) or genomic damage (via the quantitative polymerase chain reaction). In addition to these existing means of assessing virus attenuation, a novel technique of correlating transmission electron micrographs of electrocoagulated MS2 with their computationally altered three-dimensional electron density maps was developed to provide direct visual evidence of capsid morphological damages during electrocoagulation. The majority of coliphages lost at least 10-60% of the capsid protein missing a minimum of one of the 5-fold and two of 3- and 2-fold regions upon electrocoagulation, revealing substantial localized capsid deformation. Attenuated total reflectance-Fourier transform infrared spectroscopy revealed potential oxidation of viral coat proteins and modification of their secondary structures that were attributed to reactive oxygen species. Iron electrocoagulation simultaneously disinfects and coagulates non-enveloped viruses (unlike conventional coagulation), adding to the robustness of multiple barriers necessary for public health protection and appears to be a promising technology for small-scale distributed water treatment.

Pool water disinfection by ozone-bromine treatment: Assessing the disinfectant efficacy and the occurrence and in vitro toxicity of brominated disinfection by-products

Pool water is continuously circulated and reused after an extensive treatment including disinfection by chlorination, ozonation or UV treatment. In Germany, these methods are regulated by DIN standard 19643. Recently, the DIN standard has been extended by a new disinfection method using hypobromous acid as disinfectant formed by introducing ozone into water with naturally or artificially high bromide content during water treatment.In this study, we tested the disinfection efficacy of the ozone-bromine treatment in comparison to hypochlorous acid in a flow-through test rig using the bacterial indicator strains Escherichia coli, Enterococcus faecium, Pseudomonas aeruginosa, and Staphylococcus aureus and the viral indicators phage MS2 and phage PRD1. Furthermore, the formation of disinfection by-products and their potential toxic effects were investigated in eight pool water samples using different disinfection methods including the ozone-bromine treatment. Our results show that the efficacy of hypobromous acid, depending on its concentration and the tested organism, is comparable to that of hypochlorous acid. Hypobromous acid was effective against five of six tested indicator organisms. However, using Pseudomonas aeruginosa and drinking water as test water, both tested disinfectants (0.6 mg L−1 as Cl2 hypobromous acid as well as 0.3 mg L−1 as Cl2 hypochlorous acid) did not achieve a reduction of four log10 levels within 30 s, as required by DIN 19643.The formation of brominated disinfection by-products depends primarily on the bromide concentration of the filling water, with the treatment method having a smaller effect. The eight pool water samples did not show critical values in vitro for acute cytotoxicity or genotoxicity in the applied assays. In real pool water samples, the acute toxicological potential was not higher than for conventional disinfection methods. However, for a final assessment of toxicity, all single substance toxicities of known DBPs present in pool water treated by the ozone-bromine treatment have to be analyzed additionally.

Antiviral properties of select carbon nanostructures and their functionalized analogs

The antiviral properties of nanocarbons namely, carbon nanotubes (CNT), graphene oxide (GO), reduced graphene oxide (rGO), hybrid GO-CNT, rGO-CNT and CNTs functionalized with carboxylic (CNT-COOH), phenol (CNT-phenol), silver (CNT-Ag) are presented. Escherichia coli MS2 bacteriophage was the model virus. All the nanocarbons showed antiviral activities and the activity increased with increase in concentration. CNT-phenol showed the highest antiviral activity (97.1%) at 0.3mg/mL followed by CNT-Ag (90%), GO-CNT (85.5%), rGO-CNT (83.5%), CNT-COOH (82.5%), CNT (78%), GO (45.6%) and rGO (39.5%) at the same concentration. At 0.05 mg/ml, compared to pure CNTs, those functionalized with silver and phenol showed 270% and 200% higher removal efficiencies respectively. GO and rGO were less efficient by themselves, but with the CNTs, namely GO-CNT and rGO-CNT, their activities enhanced by factors of 650 and 950% respectively. The antiviral activity of the nanocarbons was quantified based on both the concentration of nanocarbons needed to reach a 50 percent deactivation (LD50) and the rate of deactivation. CNT-Phenol was the most effective antiviral nanocarbon studied here, it’s LD50 was 1400 times lower than the pure CNTs even though it had similar rate of deactivation as the latter, The antiviral efficiency of GO and rGO were relatively lower compared to the other nanocarbons, however they improved by 92% and 89% for GO and rGO when combined with the CNTs in a hybrid form. From the transmission electron microscopy (TEM) analysis, it was observed that the CNTs entangled the viruses which probably led to physical damage to their structure while the functional groups attached to CNTs such as phenol and Ag further enhanced toxicity due to their own properties.

The impact of local assembly rules on RNA packaging in a T = 1 satellite plant virus.

The vast majority of viruses consist of a nucleic acid surrounded by a protective icosahedral protein shell called the capsid. During viral infection of a host cell, the timing and efficiency of the assembly process is important for ensuring the production of infectious new progeny virus particles. In the class of single-stranded RNA (ssRNA) viruses, the assembly of the capsid takes place in tandem with packaging of the ssRNA genome in a highly cooperative co-assembly process. In simple ssRNA viruses such as the bacteriophage MS2 and small RNA plant viruses such as STNV, this cooperative process results from multiple interactions between the protein shell and sites in the RNA genome which have been termed packaging signals. Using a stochastic assembly algorithm which includes cooperative interactions between the protein shell and packaging signals in the RNA genome, we demonstrate that highly efficient assembly of STNV capsids arises from a set of simple local rules. Altering the local assembly rules results in different nucleation scenarios with varying assembly efficiencies, which in some cases depend strongly on interactions with RNA packaging signals. Our results provide a potential simple explanation based on local assembly rules for the ability of some ssRNA viruses to spontaneously assemble around charged polymers and other non-viral RNAs in vitro.

Miniaturizing Wet Scrubbers for Aerosolized Droplet Capture.

Aerosols dispersed and transmitted through the air (e.g., particulate matter pollution and bioaerosols) are ubiquitous and one of the leading causes of adverse health effects and disease transmission. A variety of sampling methods (e.g., filters, cyclones, and impactors) have been developed to assess personal exposures. However, a gap still remains in the accessibility and ease-of-use of these technologies for people without experience or training in collecting airborne samples. Additionally, wet scrubbers (large non-portable industrial systems) utilize liquid sprays to remove aerosols from the air; the goal is to "scrub" (i.e., clean) the exhaust of industrial smokestacks, not collect the aerosols for analysis. Inspired by wet scrubbers, we developed a device fundamentally different from existing portable air samplers by using aerosolized microdroplets to capture aerosols in personal spaces (e.g., homes, offices, and schools). Our aerosol-sampling device is the size of a small teapot, can be operated without specialized training, and features a winding flow path in a supersaturated relative humidity environment, enabling droplet growth. The integrated open mesofluidic channels shuttle coalesced droplets to a collection chamber for subsequent sample analysis. Here, we present the experimental demonstration of aerosol capture in water droplets. An iterative study optimized the non-linear flow manipulating baffles and enabled an 83% retention of the aerosolized microdroplets in the confined volume of our device. As a proof-of-concept for aerosol capture into a liquid medium, 0.5-3 μm model particles were used to evaluate aerosol capture efficiency. Finally, we demonstrate that the device can capture and keep a bioaerosol (bacteriophage MS2) viable for downstream analysis.

UVC inactivation of MS2-phage in drinking water – Modelling and field testing

UVC disinfection has been recognised by the WHO as an effective disinfection treatment to provide decentralized potable water. Under real conditions there are still unknowns that limit this application including the influence of suspended solids and natural organic matter. This work aims to investigate the influence of two key parameters, suspended solids and natural organic matter, on the efficiency of UVC disinfection of surface water to achieve the drinking water quality requirements established by the WHO for point of use (POU) technologies. Kaolinite (turbidity agent) and humic acids (HA, model of organic matter) were used in a factorial design of experiments (Turbidity from 0 to 5 NTU, and HA from 0 to 3.5 mg/L) to investigate their effect on UVC inactivation of MS2 phage in surface water. A collimated beam (12 W) and a commercial UVC disinfection flow system (16 W) designed to provide drinking water at households were used. The UVC flow system both in the laboratory and in the field was able to achieve the reduction requirements established by WHO (LRV >3.5 for all tested conditions), confirming the good performance of the studied UVC disinfection system. The results found in the lab were used to establish a numerical model that predicts the disinfection rate constant as a function of water turbidity and transmittance at 254 nm (confidence level>95%). The model permitted to elucidate the critical effect of low concentrations of HA in reducing the inactivation rate by 40% for 3.5 mg/L-HA compared with 0, the non-significant detrimental effect of turbidity lower than 5 NTU, and the lack of synergistic effects between both parameters at these levels. The UVC flow system was also tested in the field, in Tzabalho, Chiapas (Mexico), and Antioquia (Colombia), with spiked MS2 into natural surface water. This investigation opens a potential application to monitor the performance of UVC systems with surface water by monitoring transmittance at 254 nm as a tool to control UVC domestic systems to deliver safe drinking water in a household without the need of expensive and laborious biological monitoring tools.

Understanding the Folding Mediated Assembly of the Bacteriophage MS2 Coat Protein Dimers

The capsids of RNA viruses such as MS2 are great models for studying protein self-assembly because they are made almost entirely of multiple copies of a single coat protein (CP). Although CP is the minimal repeating unit of the capsid, previous studies have shown that CP exists as a homodimer (CP2) even in an acid-disassembled system, indicating that CP2 is an obligate dimer. Here, we investigate the molecular basis of this obligate dimerization using coarse-grained structure-based models and molecular dynamics simulations. We find that, unlike monomeric proteins of similar size, CP populates a single partially folded ensemble whose "foldedness" is sensitive to denaturing conditions. In contrast, CP2 folds similarly to single-domain proteins populating only the folded and the unfolded ensembles, separated by a prominent folding free energy barrier. Several intramonomer contacts form early, but the CP2 folding barrier is crossed only when the intermonomer contacts are made. A dissection of the structure of CP2 through mutant folding simulations shows that the folding barrier arises both from the topology of CP and the interface contacts of CP2. Together, our results show that CP2 is an obligate dimer because of kinetic stability, that is, dimerization induces a folding barrier and that makes it difficult for proteins in the dimer minimum to partially unfold and access the monomeric state without completely unfolding. We discuss the advantages of this obligate dimerization in the context of dimer design and virus stability.

An overview of silver nano-particles as promising materials for water disinfection

Open defecation, improper disposal of sewer line wastes and mismanagement of infectious biomedical wastes may cause severe biological contamination to the water reservoirs. On the other hand, high demand of drinking water has become again a challenge in terms of maintaining hygiene, safe and cleanliness. Nano-technological approaches can play significant roles in the efficient and effective disinfection of drinking water for the continuously growing world’s population without generating toxic byproducts. Non-conventional water disinfection process (or microbial inactivation) using silver nanoparticles (AgNPs) has many advantages over the other nanoparticles (NPs) because of their bactericidal, fungicidal, veridical and oligodynamic properties. It can also be conveniently incorporated into different porous cellulosic materials. Recently, it has been observed that silver-based porous nanocomposites (AgNCs) were efficiently deactivated the bacteria and viruses up to 99%–100% from drinking water. In many studies, silver based nanoparticles are found able to kill around 99.99% for E. coli and MS2 bacteriophage viruses. The present review is aimed at (1) describing the recent advances for AgNPs preparation, (2) explaining the incorporation of AgNPs into paper, polyurethane, ceramic, cotton fabrics and other polymers for water disinfection process, (3) discussing the mechanism of water disinfection/microbial inactivation using AgNPs and AgNCs, and (4) also illustrated that how water sanitation can be helpful to achieve sustainable development goals using silver NPs based developed disinfection systems? Moreover, a number of limitations and future scope have also been discussed. This review will be useful to the researchers and competent authorities engaged in water conservation and management to prepare more effective strategies by using AgNPs and AgNCs.

Antiviral properties of propolis ethanol extract against norovirus and its application in fresh juices

Human noroviruses (HuNoVs) outbreaks have been linked to contaminated fresh-cut produce. Propolis has been used as a folk medicine because of its extensive bioactivity and antimicrobial properties. The aim of this study was to investigate the antiviral properties of propolis water extracts (PWE) and propolis ethanol extracts (PEE) against noroviruses, and its application in fresh-cut produce. Extraction yields, total phenolic content, total flavonoid, and soluble carbohydrate content of the propolis extracts were measured to estimate their antiviral compounds. The HuNoV GII.4 and its surrogates (murine norovirus MNV-1 and bacteriophage MS2) were used to evaluate the anti-noroviral activities of propolis extracts. The polyphenol-rich extract (PEE) showed better antiviral activities than PWE. Time-of-addition experiments and TEM images suggested that PEE denatured the viral capsid protein and likely prevented adsorption and internalization of viruses into cells. The application of PEE for natural preservative in fresh juices was also analyzed. After 30 min of treatment of the four different juices, 500 μg/mL PEE reduced MNV-1 and MS2 titers by > 3.0 log10. Therefore, the PEE containing high amounts of polyphenol improved the safety of fresh juices and could be potential candidates for the development of novel natural antiviral preservative for fresh juices.

Aerobic Conditions and Endogenous Reactive Oxygen Species Reduce the Production of Infectious MS2 Phage by Escherichia coli.

Most of the defective/non-infectious enteric phages and viruses that end up in wastewater originate in human feces. Some of the causes of this high level of inactivity at the host stage are unknown. There is a significant gap between how enteric phages are environmentally transmitted and how we might design molecular tools that would only detect infectious ones. Thus, there is a need to explain the low proportion of infectious viral particles once replicated. By analyzing lysis plaque content, we were able to confirm that, under aerobic conditions, Escherichia coli produce low numbers of infectious MS2 phages (I) than the total number of phages indicated by the genome copies (G) with an I/G ratio of around 2%. Anaerobic conditions of replication and ROS inhibition increase the I/G ratio to 8 and 25%, respectively. These data cannot only be explained by variations in the total numbers of MS2 phages produced or in the metabolism of E. coli. We therefore suggest that oxidative damage impacts the molecular replication and assembly of MS2 phages.

Persistence of Foodborne Pathogens on Farmers' Market Fomites

The number of farmers' markets registered by the U.S. Department of Agriculture has seen a significant increase, jumping from 1,755 in 1994 to 8,771 in 2019. Although previous studies have investigated the microbial profile of produce obtained from farmers' markets, literature exploring microbial (bacteria and virus) persistence on a variety of different farmers' market fomites over a 2-month period is limited. The objective of the current study was to investigate the persistence of key foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, and MS2 bacteriophage) on these fomites by using a microbiological viability assay. The MS2 bacteriophage was quantified by using a host E. coli strain, and PFU were identified. A repeated measures analysis of variance was used to compare the persistence rates of foodborne pathogens on cardboard, plastic, tablecloth, molded pulp fiber, and wicker baskets used to store, transport, and display produce at farmers' markets. In general, molded pulp fiber, plastic, and wicker surface materials supported the persistence of foodborne pathogens the most, with Salmonella and S. aureus demonstrating the highest log concentrations over the longest period of time. Additionally, E. coli strains also persisted for a significant period of time on all fomites, with the exception of tablecloth. The results suggest that foodborne pathogens on these fomites pose a high risk of cross-contamination, particularly if the fomites cannot be washed, rinsed, and sanitized effectively (e.g., cardboard). The results highlight the need to avoid using porous, single-use storage containers, such as cardboard, molded pulp fiber, and wicker containers for extended periods of time and suggest the use of easily cleanable materials, such as plastic containers.

Surface chemistry-dependent antiviral activity of silver nanoparticles

The toxicity towards viruses of silver nanoparticles (AgNPs) has been reported to be dependent on several factors such as particle concentration, size, and shape. Although these factors may indeed contribute to the toxicity of AgNPs, the results presented in this work demonstrate that surface chemistry and especially surface charge is a crucial factor governing their antiviral activity. Here, this work investigated the influence of capping agents representing various surface charges ranging from negative to positive. These AgNPs were capped with citrate, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) mercaptoacetic acid (MAA) and (branched polyethyleneimine (BPEI). We show that AgNPs exhibited surface charge-dependent toxicity towards MS2 bacteriophages. Among the capping agents under investigation, BPEI capped AgNPs (Ag/BPEI) exhibited the highest reduction of MS2 resulting in ≥6 log10-units reductions, followed by 4–5 log10-units reductions with PVP and PEG capping’s and 3–4 log10-units with MAA and citrate cappings. Bare nanoparticles reported a mere 1–2 log10-units reduction. Electrostatic interaction between the positively charged BPEI-coating and the negatively charged virus surface played a significant role in bringing the MS2 closer to toxic silver ions (Ag+). Further results obtained from TEM showed that Ag/BPEI nanoparticles could directly damage the structure of the MS2 bacteriophages. AgNPs and cationic capping agents’ observed synergy can lead to much lower and much more efficient dosing of AgNPs for antiviral applications.

Advanced Oxidation Processes for Water and Wastewater Viral Disinfection. A Systematic Review

Water and wastewater virological quality is a significant public health issue. Viral agents include emerging and re-emerging pathogens characterized by extremely small size, and high environmental stability. Since the mainly used conventional disinfection methods are usually not able to achieve complete disinfection of viral and other microbial targets, in real water and wastewater matrices, effective strategies for the treatment, use and reuse of water and the development of next-generation water supply systems are required. The scope of the present systematic review was to summarize research data on the application of advanced oxidation processes (AOPs) for viral disinfection of water and wastewater. A literature survey was conducted using the electronic databases PubMed, Scopus, and Web of Science. This comprehensive research yielded 23 records which met the criteria and were included and discussed in this review. Most of the studies (14/23) used only MS2 bacteriophage as an index virus, while the remaining studies (9/23) used two or more viral targets, including phages (MS2, T4, T7, phiX174, PRD-1, S2, ϕB124-14, ϕcrAssphage) and/or Adenovirus, Aichivirus, Norovirus (I, II, IV), Polyomavirus (JC and BK), Sapovirus, Enterovirus, Coxsackievirus B3, Echovirus, and Pepper mild mottle virus. The vast majority of the studies applied a combination of two or more treatments and the most frequently used process was ultraviolet light-hydrogen peroxide (UV/H2O2) advanced oxidation. The review is expected to highlight the potential of the AOPs for public health protection from the waterborne viral exposure.

Sunlight Inactivation of Human Norovirus and Bacteriophage MS2 Using a Genome-Wide PCR-Based Approach and Enzyme Pretreatment.

Human norovirus (hNoV) is an important etiology of gastrointestinal illness and can be transmitted via ingestion of contaminated water. Currently impractical to culture, hNoV detection is reliant on real-time polymerase chain reaction (RT-PCR)-based methods. This approach cannot distinguish between infective and inactivated viruses because intact regions of the RNA genome can amplify even if the damage is present in other regions of the genome or because intact genetic material is not contained within an infectious virion. Herein, we employ a multiple long-amplicon RT-qPCR extrapolation approach to assay genome-wide damage and an enzymatic pretreatment to study the impact of simulated sunlight on the infectivity of hNoV in clear, sensitizer-free water. Using MS2 coliphage as an internal control, the genome-wide damage extrapolation approach, previously successfully applied for UV-254 inactivation, vastly overestimated sunlight inactivation, suggesting key differences in photoinactivation under different spectral conditions. hNoV genomic RNA was more susceptible to simulated sunlight degradation per base compared to MS2 genomic RNA, while enzymatic pretreatment indicated that hNoV experienced more capsid damage than MS2. This work provides practical and mechanistic insight into the endogenous sunlight inactivation of single-stranded RNA bacteriophage MS2, a widely used surrogate, and hNoV GII.4 Sydney, an important health-relevant virus, in clear sensitizer-free water.

Evaluation of 2 Ultraviolet-C Light Boxes for Decontamination of N95 Respirators.

Background:Ultraviolet-C (UV-C) light devices are effective in reducing contamination on N95 filtering facepiece respirators. However, limited information is available on whether UV-C devices meet the Food and Drug Administration's (FDA) microbiological requirements for Emergency Use Authorization (EUA) for respirator bioburden reduction.Methods:We tested the ability of 2 UV-C light boxes to achieve the 3-log10 microorganism reductions required for EUA for reuse by single users. Whole 3M 1860 or Moldex 1513 respirators were inoculated on the exterior facepiece, interior facepiece, and internal fibers with bacteriophage MS2 and/or 4 strains of bacteria and treated with UV-C cycles of 1 or 20 minutes. Colorimetric indicators were used to assess penetration of UV-C through the respirators.Results:For 1 UV-C box, a 20-minute treatment achieved the required bioburden reduction for Moldex 1513 but not 3M 1860 respirators. For the second UV-C box, a 1-minute treatment achieved the required bioburden reduction in 4 bacterial strains for the Moldex 1513 respirator. Colorimetric indicators demonstrated penetration of UV-C through all layers of the Moldex 1513 respirator but not the 3M 1860 respirator.Conclusions:Our findings demonstrate that UV-C box technologies can achieve bioburden reductions required by the FDA for EUA for single users but highlight the potential for variable efficacy for different types of respirators.

Genetically Encoding Ultrastable Virus-like Particles Encapsulating Functional DNA Nanostructures in Living Bacteria.

DNA nanotechnology is leading the field of in vitro molecular-scale device engineering, accumulating to a dazzling array of applications. However, while DNA nanostructures' function is robust under in vitro settings, their implementation in real-world conditions requires overcoming their rapid degradation and subsequent loss of function. Viruses are sophisticated supramolecular assemblies, able to protect their nucleic acid content in inhospitable biological environments. Inspired by this natural ability, we engineered in vitro and in vivo technologies, enabling the encapsulation and protection of functional DNA nanostructures inside MS2 bacteriophage virus-like particles (VLPs). We demonstrate the ssDNA-VLPs nanocomposites' (NCs) abilities to encapsulate single-stranded-DNA (ssDNA) in a variety of sizes (200-1500 nucleotides (nt)), sequences, and structures while retaining their functionality. Moreover, by exposing these NCs to hostile biological conditions, such as human blood serum, we exhibit that the VLPs serve as an excellent protective shell. These engineered NCs pose critical properties that are yet unattainable by current fabrication methods.