Bacteriophage-based Vaccine: A New Dawn for Vaccine Design and Development

The COVID-19 epidemic has strained healthcare systems, causing stress among personnel and facing significant economic and social issues. COVID-19 patients have significant symptoms, necessitating prompt treatment. It is a global urgency to develop effective vaccinations against COVID-19. Quick immunization of the whole world population against an ever-changing, extremely deadly virus is alarming, and various vaccine techniques are being researched. Bacteriophages are helpful in the treatment of multidrug-resistant bacterial infections. But, their clinical efficacy may go far beyond. One of the most significant bioproducts in medicine is thought to be vaccines. Vaccines for a variety of diseases have been made. However, certain vaccinations have disadvantages, such as high prices and immunological responses. In this regard, the use of bacteriophages has been suggested as an exciting alternative for making more inexpensive vaccines. Bacteriophage-displayed vaccines are based on the antigens being expressed on the phage surface. This tactic uses the inherent advantages of these particles, including their high stability, inexpensive production, and adjuvant capacity. Phage-displayed, phages DNA and hybrid phage-DNA vaccines are the three phage-based vaccines that are currently offered. The traditional method for finding novel barrier protection epitopes, antigens, and mimotopes is phage display. In this frame of reference, phage particles serve as a versatile, effective, and promising strategy for making vaccine delivery systems that are more effective and should be widely applied in the future. The phage-vaccine technique can potentially address the growing demand for innovative vaccinations against emerging diseases. This short communication addresses bacteriophage uses in vaccine development and discusses recent developments in bacteriophage-based vaccinations. It also focuses on and describes bacteriophages as a novel vaccine candidate for COVID-19. © Pakistan Academy of Sciences.

Engineered Cross-Linked Silane with Urea Polymer Thin Durable Coatings onto Polymeric Films for Controlled Antiviral Release of Activated Chlorine and Essential Oils.

In March 2020, the World Health Organization announced a pandemic attributed to SARS-CoV-2, a novel beta-coronavirus, which spread widely from China. As a result, the need for antiviral surfaces has increased significantly. Here, the preparation and characterization of new antiviral coatings on polycarbonate (PC) for controlled release of activated chlorine (Cl+) and thymol separately and combined are described. Thin coatings were prepared by polymerization of 1-[3-(trimethoxysilyl)propyl] urea (TMSPU) in ethanol/water basic solution by modified Stöber polymerization, followed by spreading the formed dispersion onto surface-oxidized PC film using a Mayer rod with appropriate thickness. Activated Cl-releasing coating was prepared by chlorination of the PC/SiO2-urea film with NaOCl through the urea amide groups to form a Cl-amine derivatized coating. Thymol releasing coating was prepared by linking thymol to TMSPU or its polymer via hydrogen bonds between thymol hydroxyl and urea amide groups. The activity towards T4 bacteriophage and canine coronavirus (CCV) was measured. PC/SiO2-urea-thymol enhanced bacteriophage persistence, while PC/SiO2-urea-Cl reduced its amount by 84%. Temperature-dependent release is presented. Surprisingly, the combination of thymol and chlorine had an improved antiviral activity, reducing the amount of both viruses by four orders of magnitude, indicating synergistic activity. For CCV, coating with only thymol was inactive, while SiO2-urea-Cl reduced it below a detectable level.

Opportunistic Respiratory Pathogens in Symptomatic Non- Covid-19 Adults during a Presumptive Influenza Season

Intro: It is hypothesized that metagenomics could contribute to the effective sentinel surveillance of emerging infections to identify plausible cause of respiratory symptoms in the population. Method(s): This study forms part of a longitudinal household cohort study involving the collection of respiratory symptoms and vaccination history in Hong Kong. As a pilot, selected households were provided with swab collection kit for collecting nasopharyngeal and throat samples when there was an influenza-like illness (ILI) during a 4-month presumptive period of the year's winter influenza season. Sequence-Independent Single Primer Amplification (SISPA) and nanopore metagenomic sequencing were performed. After basecalling, demultiplexing, and quality filtering, taxonomic classification was done. Unclassified and host reads were removed and only taxon with over 0.1% abundance were included in the analysis. Finding(s): Between December 2021 and April 2022, of 101 collection kits delivered, 36 (36%) participants returned the samples. Two (6%) had previous COVID-19 diagnosis and almost all (97%) received at least one dose of COVID-19 vaccination. Metagenomics sequencing was performed on 13 samples collected from participants when ILI was present. Of the 1,592,219 reads obtained, 5308 taxa were identified and 136 had over 0.1% abundance, including 128 bacteria, 6 fungi, and 1 virus, which was a bacteriophage. The five most abundant genera of bacteria included Neisseria (19%), Streptococcus (10%), Haemophilus (9%), Veillonella (3%), and Rothia (3%). Haemophilus parainfluenzae was the most abundant species with 97,542 (6%) reads, followed by Neisseria meningitides (5%). Other bacteria identified included Rothia mucilaginosa, Acinetobacter baumannii, Lautropia mirabilis, Veillonella atypica, Streptococcus salivarius, and Streptococcus pneumonia. Inter-participant abundance profile was significantly different (p<0.001). Conclusion(s): The absence of viral infections identified echoed the extremely low proportion (3/21986, or 0.01%) of respiratory specimens testing positive for influenza virus by the government laboratory during the same period. The metagenomic profile could be useful for identifying the likely ILI-causing pathogen.Copyright © 2023

The fate of SARS-CoV-2 viral RNA in coastal New England wastewater treatment plants

Municipal sewage carries SARS-CoV-2 viruses shed in the human stool by infected individuals to wastewater treatment plants (WWTPs). It is well-established that increasing prevalence of COVID-19 in a community increases the viral load in its WWTPs. Despite the fact that wastewater treatment facilities serve a critical role in protecting downstream human and environmental health through removal or inactivation of the virus, little is known about the fate of the virus along the treatment train. To assess the efficacy of differing WWTP size and treatment processes in viral RNA removal we quantified two SARS-CoV-2 nucleocapsid (N) biomarkers (N1 and N2) in both liquid and solids phases for multiple treatment train locations from seven coastal New England WWTPs. SARS-CoV-2 biomarkers were commonly detected in the influent, primary treated, and sludge samples (returned activated sludge, waste activated sludge, and digested sludge), and not detected after secondary clarification processes or disinfection. Solid fractions had 470 to 3,700-fold higher concentrations of viral biomarkers than liquid fractions, suggesting considerably higher affinity of the virus for the solid phase. Our findings indicate that a variety of wastewater treatment designs are efficient at achieving high removal of SARS CoV-2 from effluent;however, quantifiable viral RNA was commonly detected in wastewater solids at various points in the facility. This study supports the important role municipal wastewater treatment facilities serve in reducing the discharge of SARS-CoV-2 viral fragments to the environment and highlights the need to better understand the fate of this virus in wastewater solids.

Antiviral activity of nano-monocaprin against Phi6 as a surrogate for SARS-CoV-2.

The COVID-19 pandemic involving SARS-CoV-2 has raised interest in using antimicrobial lipid formulations to inhibit viral entry into their host cells or to inactivate them. Lipids are a part of the innate defense mechanism against pathogens. Here, we evaluated the use of nano-monocaprin (NMC) in inhibiting enveloped (phi6) and unenveloped (MS2) bacteriophages. NMC was prepared using the sonochemistry technique. Size and morphology analysis revealed the formation of ~ 8.4 ± 0.2-nm NMC as measured by dynamic light scattering. We compared the antiviral activity of NMC with molecular monocaprin (MMC) at 0.5 mM and 2 mM concentrations against phi6, which we used as a surrogate for SARS-CoV-2. The synthesized NMC exhibited 50% higher antiviral activity against phi6 than MMC at pH 7 using plaque assay. NMC inactivated phi6 stronger at pH 4 than at pH 7. To determine if NMC is toxic to mammalian cells, we used MTS assay to assess its IC50 for HPDE and HeLa cell lines, which were ~ 203 and 221 µM, respectively. NMC may be used for prophylactic application either as a drop or spray since many viruses enter the human body through the mucosal lining of the nose, eyes, and lungs.

Efficacy evaluation of an air-assisted electrostatic disinfection device for the effective disinfection and sanitization against the spread of pathogenic infections

This research aims to check the chargeability of sodium hypochlorite and the efficacy evaluation of an air-assisted electrostatic disinfection device. Five different inanimate surfaces i.e., wood, glass, stainless steel, plastic and fabric were considered to examine the performance in terms of efficacy, survival time, off-target losses, spray coverage and the volume of disinfectant consumed. A significant charge-to-mass level of 2.43 mC/kg was achieved for sodium hypochlorite at an applied voltage of 2.0 kV, a liquid flowrate of 253 ml/min and applied air pressure of 4.0 bar. The experimental results found that 1000 mg/L of sodium hypochlorite concentration effectively eliminated Pseudomonas aeruginosa, Clostridium perfringens and Bacteriophage MS2 colonies. © 2023 Elsevier B.V.

Quantifying the reduction of airborne infectious viral load using a ventilated patient hood.

BACKGROUND: Healthcare workers treating SARS-CoV-2 patients are at risk of infection by respiratory exposure to patient-emitted, virus-laden aerosols. Source control devices such as ventilated patient isolation hoods have been shown to limit the dissemination of non-infectious airborne particles in laboratory tests, but data on their performance in mitigating the airborne transmission risk of infectious viruses are lacking. AIM: We used an infectious airborne virus to quantify the ability of a ventilated hood to reduce infectious virus exposure in indoor environments. METHODS: We nebulized 109 plaque forming units (pfu) of bacteriophage PhiX174 virus into a ∼30-m3 room when the hood was active or inactive. The airborne concentration of infectious virus was measured by BioSpot-VIVAS and settle plates using plaque assay quantification on the bacterial host Escherichia coli C. The airborne particle number concentration (PNC) was also monitored continuously using an optical particle sizer. FINDINGS: The median airborne viral concentration in the room reached 1.41 × 105 pfu/m3 with the hood inactive. When active, the hood reduced infectious virus concentration in air samples by 374-fold. The deposition of infectious virus on the surface of settle plates was reduced by 87-fold. This was associated with a 109-fold reduction in total airborne particle number escape rate. CONCLUSION: A personal ventilation hood significantly reduced airborne particle escape, considerably lowering infectious virus contamination in an indoor environment. Our findings support the further development of source control devices to mitigate nosocomial infection risk among healthcare workers exposed to airborne viruses in clinical settings.

RESISTANCE FACTORS OF KLEBSIELLA PNEUMONIAE BACTERIA DURING COVID-19 PANDEMIC.

Multidrug-resistant K. pneumoniae bacterial strains producing extended range of beta-lactamases or carbapenemases are of serious clinical concern. The aim of the study was to determine the resistance factors of K. pneumoniae strains isolated from the lower respiratory tract of patients diagnosed with community-acquired pneumonia during the COVID-19 pandemic. Materials and methods. The study of resistance to antimicrobial drugs included 138 strains of K. pneumoniae isolated from the sputum of patients treated in infectious diseases monohospitals in the city of Tyumen and the Tyumen region within the period from May 2020 to June 2021. Among the strains examined, 51.4% of them were isolated from SARS-CoV-2 positive patients. The presence of resistance genes was determined by PCR in 71 strains of K. pneumoniae (34 strains from COVID-19-positive and 37 strains from COVID-19-negative patients). Identification of isolated bacterial strains was carried out according to the protein spectra by using a desktop time-of-flight mass spectrometer with matrix laser desorption MALDI-TOF MS (Bruker, Germany). The belonging of the strains to the hypermucoid phenotype was determined using the string test. Sensitivity to antimicrobial drugs was assessed in the disk diffusion method on Muller-Hinton medium. The sensitivity of culture strains to bacteriophage preparations was determined by the drop method (spot-test). In the study, we used "Polyvalent Sextaphage Pyobacteriophage" and "Purified Polyvalent Klebsiella Bacteriophage", JSC NPO Microgen, Russia. Detection of resistance genes to beta-lactam antibiotics by real-time PCR was carried out using the BakRezista kit (OOO DNA-technology, Russia). The results of the study evidence that K. pneumoniae bacteria isolated from COVID-19-positive and COVID-19-negative patients diagnosed with community-acquired pneumonia displayed a high resistance to antimicrobial drugs and commercial phage-containing drugs. Resistance of K. pneumoniae strains was recorded from 50% (to aminoglycosides and carbapenems) to 90% (to inhibitor-protected penicillins). Sensitivity to bacteriophages was noted on average in no more than 20% of strains. It is important to emphasize that strains isolated from COVID-19-positive patients more often showed a hypermucoid phenotype, suggesting a high bacterial virulence, and also showed greater resistance to all groups of antibacterial drugs examined in the study, which is confirmed by the presence of resistance genes of the ESBL group and carbapenemase. The results of the study suggest that the high level of resistance of K. pneumoniae strains isolated from COVID-19-positive patients is associated with immunosuppression provoked by the SARS-CoV-2 virus, which contributes to their colonization by more virulent strains.Copyright © 2022 Saint Petersburg Pasteur Institute. All rights reserved.

Identification of highly immunogenic epitopes in the SARS-CoV-2 Spike protein to produce monoclonal antibodies

Background: In outpatients, monoclonal antibodies to Spike protein reduce viral load and improve outcomes, with a greater effect in serum antibody-negative at baseline. The aim of this study was to find epitope candidates to produce neutralizing monoclonal antibodies (mAb) for COVID-19 treatment. Method(s): IgG COVID-19 patients (N=500) against SARS-CoV-2 was confirmed. Epitope mapping was performed by Luminex technology. A computational pipeline based in predictive models was designed to predict S protein epitopes most likely to be recognized by mAb from COVID-19 convalescent patients. Result(s): Validation Screening: 29 epitopes of the SARS-CoV-2 S protein were predicted by our pipeline and included in the Luminex panel. 40 serum samples from convalescent COVID-19 patients and 126 pre-pandemia negative controls were included in the validation screening. Epitope mapping: 500 serum samples were tested against the 8 epitopes selected in the validation screening. The two epitopes with the highest IgG of participants above the seropositivity cut-offs were selected. The two most immunogenic epitopes were screened in phage library containing 109 clones of antibodies anti-SARS-CoV-2 to produce mAbs by phage display technology. Conclusion(s): The two epitopes with the highest IgG reactivity validated against serum samples from 500 COVID-19 convalescent patients and phage library are good candidates for the production of new neutralizing mAbs against SARS-CoV-2 S protein.

The Quinolone Resistance Genes in the Bacteriophage DNA Fractions in the Healthy Calf Stool Samples Via qPCR

The One Health approach shows that people, animals, plants, and environmental factors can affect each other. Phages are one of the mobile genetic elements. Quinolones are a critical group of antibiotics for both human and animal health and monitoring their antimicrobial resistance is very important. The aim of the study is to determine the frequency of the quinolone resistance gene in bacteriophage DNA fractions obtained from healthy calf stool samples. In our study, 50 samples from 6-9 months old calves, which were found to be healthy and not treated with any group of antibiotics in Sanliurfa province, were included. DNA isolation was made from phage lysates of stool samples and specific primers were used qnrA, qnrB and qnrS genes. qPCR was performed on LightCycler480. Despite not receiving any antibiotic treatment, qnrB was the most detected gene among the phage DNA fractions detected in 11 calves. While qnrA, qnrB and qnrS quinolone resistance genes were detected together in one sample, qnrB and qnrS resistance genes were found together in two samples. Our data, obtained from the study in Turkiye to search for antimicrobial resistance genes in phage fractions, showed the importance of the One Health approach and determined that it was highly effective in quinolone resistance gene shedding in healthy calves that had never been treated with antibiotics. It has been concluded that in empirical treatment with quinolone, attention should be paid to all living things and unconscious antibiotic use may cause the spread of resistance genes more than expected.Copyright © 2023, Veteriner Fakultesi Dergisi. All rights reserved.

Current pandemic COVID-19 vaccine strategies and development: a comprehensive review

The coronavirus disease-19 pandemic with the characteristics of asymptomatic condition, long incubation period and poor treatment has influenced the entire globe. Coronaviruses are important emergent pathogens, specifically, the recently emerged sever acute respiratory syndrome coronavirus 2, the causative virus of the current COVID-19 pandemic. To mitigate the virus and curtail the infection risk, vaccines are the most hopeful solution. The protein structure and genome sequence of SARS-CoV-2 were processed and provided in record time;providing feasibility to the development of COVID-19 vaccines. In an unprecedented scientific and technological effort, vaccines against SARS-CoV-2 have been developed in less than one year. This review addresses the approaches adopted for SARS-CoV-2 vaccine development and the effectiveness of the currently approved vaccines.Copyright © 2023, Finlay Ediciones. All rights reserved.

Aspects of Phage-Based Vaccines for Protein and Epitope Immunization.

Because vaccine development is a difficult process, this study reviews aspects of phages as vaccine delivery vehicles through a literature search. The results demonstrated that because phages have adjuvant properties and are safe for humans and animals, they are an excellent vaccine tool for protein and epitope immunization. The phage genome can easily be manipulated to display antigens or create DNA vaccines. Additionally, they are easy to produce on a large scale, which lowers their manufacturing costs. They are stable under various conditions, which can facilitate their transport and storage. However, no medicine regulatory agency has yet authorized phage-based vaccines despite the considerable preclinical data confirming their benefits. The skeptical perspective of phages should be overcome because humans encounter bacteriophages in their environment all the time without suffering adverse effects. The lack of clinical trials, endotoxin contamination, phage composition, and long-term negative effects are some obstacles preventing the development of phage vaccines. However, their prospects should be promising because phages are safe in clinical trials; they have been authorized as a food additive to avoid food contamination and approved for emergency use in phage therapy against difficult-to-treat antibiotic-resistant bacteria. Therefore, this encourages the use of phages in vaccines.

Efficacy of Grignard Pure to Inactivate Airborne Phage MS2, a Common SARS-CoV-2 Surrogate.

Grignard Pure (GP) is a unique and proprietary blend of triethylene glycol (TEG) and inert ingredients designed for continuous antimicrobial treatment of air. TEG has been designated as a ″Safer Chemical" by the US EPA. GP has already received approval from the US EPA under its Section 18 Public Health Emergency Exemption program for use in seven states. This study characterizes the efficacy of GP for inactivating MS2 bacteriophage─a nonenveloped virus widely used as a surrogate for SARS-CoV-2. Experiments measured the decrease in airborne viable MS2 concentration in the presence of different concentrations of GP from 60 to 90 min, accounting for both natural die-off and settling of MS2. Experiments were conducted both by introducing GP aerosol into air containing MS2 and by introducing airborne MS2 into air containing GP aerosol. GP is consistently able to rapidly reduce viable MS2 bacteriophage concentration by 2-3 logs at GP concentrations of 0.04-0.5 mg/m3 (corresponding to TEG concentrations of 0.025 to 0.287 mg/m3). Related GP efficacy experiments by the US EPA, as well as GP (TEG) safety and toxicology, are also discussed.

Isolation, characterization, therapeutic potency, and genomic analysis of a novel bacteriophage vB_KshKPC-M against carbapenemase-producing Klebsiella pneumoniae strains (CRKP) isolated from Ventilator-associated pneumoniae (VAP) infection of COVID-19 patients.

BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a significant clinical problem, given the lack of therapeutic options. The CRKP strains have emerged as an essential worldwide healthcare issue during the last 10 years. Global expansion of the CRKP has made it a significant public health hazard. We must consider to novel therapeutic techniques. Bacteriophages are potent restorative cases against infections with multiple drug-resistant bacteria. The Phages offer promising prospects for the treatment of CRKP infections. OBJECTIVE: In this study, a novel K. pneumoniae phage vB_KshKPC-M was isolated, characterized, and sequenced, which was able to infect and lyse Carbapenem-resistant K. pneumoniae host specifically. METHODS: One hundred clinical isolates of K. pneumoniae were collected from patients with COVID-19 associated with ventilator-associated acute pneumonia hospitalized at Shahid Beheshti Hospital, Kashan, Iran, from 2020 to 2021. Initially, all samples were cultured, and bacterial isolates identified by conventional biochemical tests, and then the ureD gene was used by PCR to confirm the isolates. The Antibiotic susceptibility test in the disc diffusion method and Minimum inhibitory concentrations for Colistin was done and interpreted according to guidelines. Phenotypic and molecular methods determined the Carbapenem resistance of isolates. The blaKPC, blaNDM, and blaOXA-23 genes were amplified for this detection. Biofilm determination of CRKP isolates was performed using a quantitative microtiter plate (MTP) method. The phage was isolated from wastewater during the summer season at a specific position from Beheshti Hospital (Kashan, Iran). The sample was processed and purified against the bacterial host, a CRKP strain isolated from a patient suffering from COVID-19 pneumoniae and resistance to Colistin with high potency for biofilm production. This isolate is called Kp100. The separated phages were diluted and titration by the double overlay agar plaque assay. The separate Phage is concentrated with 10% PEG and stored at -80 °C until use. The phage host range was identified by the spot test method. The purified phage morphology was determined using a transmission electron microscope. The phage stability tests (pH and temperature) were analyzed. The effect of cationic ions on phage adsorption was evaluated. The optimal titer of bacteriophage was determined to reduce the concentration of the CRKP strain. One-step growth assays were performed to identify the purified phage burst's latent cycle and size. The SDS-PAGE was used for phage proteins analysis. Phage DNA was extracted by chloroform technique, and the whole genome of lytic phage was sequenced using Illumina HiSeq technology (Illumina, San Diego, CA). For quality assurance and preprocessing, such as trimming, Geneious Prime 2021.2.2 and Spades 3.9.0. The whole genome sequence of the lytic phage is linked to the GenBank database accession number. RASTtk-v1.073 was used to predict and annotate the ORFs. Prediction of ORF was performed using PHASTER software. ResFinder is used to assess the presence of antimicrobial resistance and virulence genes in the genome. The tRNAs can-SE v2.0.6 is used to determine the presence of tRNA in the genome. Linear genome comparisons of phages and visualization of coding regions were performed using Easyfig 2.2.3 and Mauve 2.4.0. Phage lifestyles were predicted using the program PHACTS. Phylogenetic analysis and amino acid sequences of phage core proteins, such as the major capsid protein. Phylogenies were reconstructed using the Neighbor-Joining method with 1000 bootstrap repeat. HHpred software was used to predict depolymerase. In this study, GraphPad Prism version 9.1 was used for the statistical analysis. Student's t-test was used to compare the sets and the control sets, and the significance level was set at P ≤ 0.05. RESULTS: Phage vB_KshKPC-M is assigned to the Siphoviridae, order Caudovirales. It was identified as a linear double-stranded DNA phage of 54,378 bp with 50.08% G + C content, had a relatively broad host range (97.7%), a short latency of 20 min, and a high burst size of 260 PFU/cell, and was maintained stable at different pH (3-11) and temperature (45-65 °C). The vB_KshKPC-M genome contains 91 open-reading frames. No tRNA, antibiotic resistance, toxin, virulence-related genes, or lysogen-forming gene clusters were detected in the phage genome. Comparative genomic analysis revealed that phage vB_KshKPC-M has sequence similarity to the Klebsiella phages, phage 13 (NC_049844.1), phage Sushi (NC_028774.1), phage vB_KpnD_PeteCarol (OL539448.1) and phage PWKp14 (MZ634345.1). CONCLUSION: The broad host range and antibacterial activity make it a promising candidate for future phage therapy applications. The isolated phage was able to lyse most of the antibiotic-resistant clinical isolates. Therefore, this phage can be used alone or as a phage mixture in future studies to control and inhibit respiratory infections caused by these bacteria, especially in treating respiratory infections caused by resistant strains in sick patients.

Room-Based Assessment of Mobile Air Cleaning Devices Using a Bioaerosol Challenge.

Introduction: The widespread transmission of the SARS-CoV-2 virus has increased scientific and societal interest in air cleaning technologies, and their potential to mitigate the airborne spread of microorganisms. Here we evaluate room scale use of five mobile air cleaning devices. Methods: A selection of air cleaners, containing high efficiency filtration, was tested using an airborne bacteriophage challenge. Assessments of bioaerosol removal efficacy were undertaken using a decay measurement approach over 3 h, with air cleaner performance compared with bioaerosol decay rate without an air cleaner in the sealed test room. Evidence of chemical by-product emission was also checked, as were total particle counts. Results: Bioaerosol reduction, exceeding natural decay, was observed for all air cleaners. Reductions ranged between devices from <2-log per m3 room air for the least effective, to a >5-log reduction for the most efficacious systems. One system generated detectable ozone within the sealed test room, but ozone was undetectable when the system was run in a normally ventilated room. Total particulate air removal trends aligned with measured airborne bacteriophage decline. Discussion: Air cleaner performance differed, and this could relate to individual air cleaner flow specifications as well as test room conditions, such as air mixing during testing. However, measurable reductions in bioaerosols, beyond natural airborne decay rate, were observed. Conclusion: Under the described test conditions, air cleaners containing high efficiency filtration significantly reduced bioaerosol levels. The best performing air cleaners could be investigated further with improved assay sensitivity, to enable measurement of lower residual levels of bioaerosols.

Establishment and application of test methodology demonstrating the functionality of air purification systems in reducing virus-loaded aerosol in indoor air.

BACKGROUND: The global COVID-19 pandemic has resulted in a greater interest in improving the ventilation of indoor environments in order to remove aerosolized virus and thus reduce transmission. Air purification systems have been proposed as a solution to improve aerosol removal. AIM: The aim was to determine the efficacy of air purification systems in reducing the viral load in the environmental air of a room. METHODS: A containment room equipped with HEPA filter on air intake and exhaust was constructed. It was connected via an inlet with the BSL-2 facility. From the BSL-2, Feline Coronavirus (FCoV)-loaded aerosols were released into the containment room. After nebulization, air sampling was performed to determine the viral load in air prior to assessing the clean air delivery rate of the air purification systems. The infectivity of the captured viruses was also examined. FINDINGS: The air purification systems realized a 97-99% reduction in viral load in air in 1 h. Captured infectious FCoV was reduced by 99.9%-99.99% by use of an ESP technology. CONCLUSIONS: The air purification systems, using ESP technology or HEPA filter, reduce the viral load in air. The ESP purifiers inactivate captured FCoV viruses. Therefore, air purification systems can be used as an adjunctive infection control measure.

Performance evaluation of an electrostatic precipitator with a copper plate using an aerosolized SARS-CoV-2 surrogate (bacteriophage phi 6).

The global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has reminded us of the importance of developing technologies to reduce and control bioaerosols in built environments. For bioaerosol control, the interaction between researchers and biomaterials is essential, and considering the characteristics of target pathogens is strongly required. Herein, we used enveloped viral aerosols, bacteriophage phi 6, for evaluating the performance of an electrostatic precipitator (ESP) with a copper-collecting plate (Cu-plate). In particular, bacteriophage phi 6 is an accessible enveloped virus that can be operated in biosafety level (BSL)-1 as a promising surrogate for SARS-CoV-2 with structural and morphological similarities. ESP with Cu-plate showed >91% of particle removal efficiency for viral aerosols at 77 cm/s of airflow face velocity. Moreover, the Cu-plate presented a potent antiviral performance of 5.4-relative log reduction within <15 min of contact. We believe that the evaluation of ESP performance using an aerosolized enveloped virus and plaque assay is invaluable. Our results provide essential information for the development of bioaerosol control technologies that will lead the post-corona era.

Analysis of Bacteriophage Behavior of a Human RNA Virus, SARS-CoV-2, through the Integrated Approach of Immunofluorescence Microscopy, Proteomics and D-Amino Acid Quantification.

SARS-CoV-2, one of the human RNA viruses, is widely studied around the world. Significant efforts have been made to understand its molecular mechanisms of action and how it interacts with epithelial cells and the human microbiome since it has also been observed in gut microbiome bacteria. Many studies emphasize the importance of surface immunity and also that the mucosal system is critical in the interaction of the pathogen with the cells of the oral, nasal, pharyngeal, and intestinal epithelium. Recent studies have shown how bacteria in the human gut microbiome produce toxins capable of altering the classical mechanisms of interaction of viruses with surface cells. This paper presents a simple approach to highlight the initial behavior of a novel pathogen, SARS-CoV-2, on the human microbiome. The immunofluorescence microscopy technique can be combined with spectral counting performed at mass spectrometry of viral peptides in bacterial cultures, along with identification of the presence of D-amino acids within viral peptides in bacterial cultures and in patients' blood. This approach makes it possible to establish the possible expression or increase of viral RNA viruses in general and SARS-CoV-2, as discussed in this study, and to determine whether or not the microbiome is involved in the pathogenetic mechanisms of the viruses. This novel combined approach can provide information more rapidly, avoiding the biases of virological diagnosis and identifying whether a virus can interact with, bind to, and infect bacteria and epithelial cells. Understanding whether some viruses have bacteriophagic behavior allows vaccine therapies to be focused either toward certain toxins produced by bacteria in the microbiome or toward finding inert or symbiotic viral mutations with the human microbiome. This new knowledge opens a scenario on a possible future vaccine: the probiotics vaccine, engineered with the right resistance to viruses that attach to both the epithelium human surface and gut microbiome bacteria.

Virus Occurrence and Survival in Reusable Resources: A Minireview

This work covers important aspects of the occurrence and viability of various viruses in the two most common reusable waste resources: wastewater and biomass waste. Detection of human, bacterial and plant viruses in these wastes are summarized. Historically, human viruses have been monitored in wastewater for decades. Evidence suggests that wastewater mostly contains fecal-orally transmitted viruses, which are abundant and diverse. Recently, an increasing occurrence of SARS-CoV2 in sewage water with the spreading epidemics has been confirmed but lacking biological proof of infectivity yet. Besides human pathogens, wastewater is shown to be rich in bacteriophages and plant viruses as well, which supposedly enter the water from human guts. Viruses serving as water quality indicators are also discussed here. Lastly, we focus on biomass waste treatment, showing the presence of some common and stable plant viruses which may supposedly survive the technological process. Copyright © Publisher PH <<Akademperiodyka>> of the NAS of Ukraine, 2022.

Ultrashort Peptides for the Self-Assembly of an Antiviral Coating

Antiviral compounds are important for generating sterile surfaces. Here, two extremely short peptides, DOPA-Phe-NH2 and DOPA-Phe(4F)-NH2 that can self-assemble into spherical nanoparticles with antiviral activity are presented. The peptide assemblies possess excellent antiviral activity against bacteriophage T4 with antiviral minimal inhibitory concentrations of 125 and 62.5 µg mL−1, for DOPA-Phe-NH2 and DOPA-Phe(4F)-NH2, respectively. When the peptide assemblies are applied on a glass substrate by drop-casting, they deactivate more than 99.9% of bacteriophage T4 and Canine coronavirus. Importantly, the peptide assemblies have low toxicity toward mammalian cells. Overall, the findings can provide a novel strategy for the design and development of antiviral coatings for a decreased risk of viral infections. © 2023 The Authors. Advanced Materials Interfaces published by Wiley-VCH GmbH.