The virucidal effects of 405 nm visible light on SARS-CoV-2 and influenza A virus.

The germicidal potential of specific wavelengths within the electromagnetic spectrum is an area of growing interest. While ultra-violet (UV) based technologies have shown satisfactory virucidal potential, the photo-toxicity in humans coupled with UV associated polymer degradation limit their use in occupied spaces. Alternatively, longer wavelengths with less irradiation energy such as visible light (405 nm) have largely been explored in the context of bactericidal and fungicidal applications. Such studies indicated that 405 nm mediated inactivation is caused by the absorbance of porphyrins within the organism creating reactive oxygen species which result in free radical damage to its DNA and disruption of cellular functions. The virucidal potential of visible-light based technologies has been largely unexplored and speculated to be ineffective given the lack of porphyrins in viruses. The current study demonstrated increased susceptibility of lipid-enveloped respiratory pathogens of importance such as SARS-CoV-2 (causative agent of COVID-19) and influenza A virus to 405 nm, visible light in the absence of exogenous photosensitizers thereby indicating a potential alternative porphyrin-independent mechanism of visible light mediated viral inactivation. These results were obtained using less than expected irradiance levels which are considered safe for humans and commercially achievable. Our results support further exploration of the use of visible light technology for the application of continuous decontamination in occupied areas within hospitals and/or infectious disease laboratories, specifically for the inactivation of respiratory pathogens such as SARS-CoV-2 and Influenza A.

Development of a novel self-sanitizing mask prototype to combat the spread of infectious disease and reduce unnecessary waste.

With the spread of COVID-19, significant emphasis has been placed on mitigation techniques such as mask wearing to slow infectious disease transmission. Widespread use of face coverings has revealed challenges such as mask contamination and waste, presenting an opportunity to improve the current technologies. In response, we have developed the Auto-sanitizing Retractable Mask Optimized for Reusability (ARMOR). ARMOR is a novel, reusable face covering that can be quickly disinfected using an array of ultraviolet C lamps contained within a wearable case. A nanomembrane UVC sensor was used to quantify the intensity of germicidal radiation at 18 different locations on the face covering and determine the necessary exposure time to inactivate SARS-CoV-2 in addition to other viruses and bacteria. After experimentation, it was found that ARMOR successfully provided germicidal radiation to all areas of the mask and will inactivate SARS-CoV-2 in approximately 180 s, H1N1 Influenza in 130 s, and Mycobacterium tuberculosis in 113 s, proving that this design is effective at eliminating a variety of pathogens and can serve as an alternative to traditional waste-producing disposable face masks. The accessibility, ease of use, and speed of sanitization supports the wide application of ARMOR in both clinical and public settings.

Low Doses of Radiation Increase the Immunosuppressive Profile of Lung Macrophages During Viral Infection and Pneumonia.

PURPOSE: Severe pneumonia and acute respiratory distress syndrome (ARDS) have been described in patients with severe coronavirus disease 2019 (COVID-19). Recently, early clinical data reported the feasibility of low doses of radiation therapy (RT) in the treatment of ARDS in patients with severe COVID-19. However, the involved mechanisms remained unknown. METHODS AND MATERIALS: Here, we used airways-instilled lipopolysaccharide (LPS) and influenza virus (H1N1) as murine models of pneumonia, and toll-like receptor (TLR)-3 stimulation in human lung macrophages. RESULTS: Low doses of RT (0.5-1 Gray) decreased LPS-induced pneumonia, and increased the percentage of nerve- and airway-associated macrophages producing interleukin (IL) 10. During H1N1 viral infection, we observed decreased lung tissue damage and immune cell infiltration in irradiated animals. Low doses of RT increased IL-10 production by infiltrating immune cells into the lung. Irradiation of TLR-3 ligand-stimulated human lung macrophages ex vivo increased IL-10 secretion and decreased interferon γ production in the culture supernatant. The percentage of human lung macrophages producing IL-6 was also decreased. CONCLUSIONS: Our data highlight a mechanism by which low doses of RT regulate lung inflammation and skew lung macrophages toward an anti-inflammatory profile. These data provide a preclinical mechanistic support to clinical trials evaluating low doses of RT, such as COVID-19-induced ARDS.

Spectrum of virucidal activity from ultraviolet to infrared radiation.

The COVID-19 pandemic has sparked a demand for safe and highly effective decontamination techniques for both personal protective equipment (PPE) and hospital and operating rooms. The gradual lifting of lockdown restrictions warrants the expansion of these measures into the outpatient arena. Ultraviolet C (UVC) radiation has well-known germicidal properties and is among the most frequently reported decontamination techniques used today. However, there is evidence that wavelengths beyond the traditional 254 nm UVC - namely far UVC (222 nm), ultraviolet B, ultraviolet A, visible light, and infrared radiation - have germicidal properties as well. This review will cover current literature regarding the germicidal effects of wavelengths ranging from UVC through the infrared waveband with an emphasis on their activity against viruses, and their potential applicability in the healthcare setting for general decontamination during an infectious outbreak.

The efficacy of vacuum-ultraviolet light disinfection of some common environmental pathogens.

BACKGROUND: This study is to elucidate the disinfection effect of ozone producing low-pressure Hg vapor lamps against human pathogens. Ozone producing low-pressure Hg vapor lamps emit mainly 254 nm ultraviolet light C (UVC) with about 10% power of Vacuum-ultraviolet (VUV) light at 185 nm. The combination of UVC and VUV can inactivate airborne pathogens by disrupting the genetic materials or generation of reactive oxygen species, respectively. In this study, inactivation of common bacteria including Escherichia coli ATCC25922 (E. coli), Extended Spectrum Beta-Lactamase-producing E. coli (ESBL), Methicillin-resistant Staphylococcus aureus (MRSA) and Mycobacterium tuberculosis (MTB), and that of influenza A viruses H1N1 and H3N2 under the radiation from ozone producing low-pressure Hg vapor lamps was examined. Log reduction values at different treatment durations were determined. METHODS: In vitro tests were carried out. Various bacterium and virus suspensions were added onto nitrocellulose filter papers and subjected to the illumination from ozone producing low-pressure Hg vapor lamps. The extents of pathogen inactivation at different illumination times were investigated by conducting a series of experiments with increasing duration of illumination. log10 reduction in CFU/ml and reduction at log10(TCID50) were respectively measured for bacteria and viruses. The disinfection effectiveness of this type of lamps against the pathogens under the environment with a moderate barrier to light was therefore evaluated. RESULTS: Ozone producing low-pressure Hg vapor lamp successfully inactivated these human pathogens. Nevertheless, among these pathogens, disinfection of MTB required more intense treatment. In the best tested situation, 3-log10 inactivation of pathogens can be achieved with ≤10 min of VUV treatment except MTB which needed about 20 min. This demonstrated the high resistance against UV disinfection of MTB. CONCLUSIONS: Following the criteria that valid germicidal results can be reflected with 3-log10 inactivation for bacteria, 4-log10 inactivation for viruses and 5-log10 inactivation for MTB, most of the bacteria required ≤10 min of VUV treatment, 20 min for the influenza viruses while MTB needed about 30 min VUV treatment. This indicated that VUV light is an effective approach against different environmental microorganisms.

Identification and Characterization of Novel Compounds with Broad-Spectrum Antiviral Activity against Influenza A and B Viruses.

Influenza A (IAV) and influenza B (IBV) viruses are highly contagious pathogens that cause fatal respiratory disease every year, with high economic impact. In addition, IAV can cause pandemic infections with great consequences when new viruses are introduced into humans. In this study, we evaluated 10 previously described compounds with antiviral activity against mammarenaviruses for their ability to inhibit IAV infection using our recently described bireporter influenza A/Puerto Rico/8/34 (PR8) H1N1 (BIRFLU). Among the 10 tested compounds, eight (antimycin A [AmA], brequinar [BRQ], 6-azauridine, azaribine, pyrazofurin [PF], AVN-944, mycophenolate mofetil [MMF], and mycophenolic acid [MPA]), but not obatoclax or Osu-03012, showed potent anti-influenza virus activity under posttreatment conditions [median 50% effective concentration (EC50) = 3.80 nM to 1.73 µM; selective index SI for 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, >28.90 to 13,157.89]. AmA, 6-azauridine, azaribine, and PF also showed potent inhibitory effect in pretreatment (EC50 = 0.14 µM to 0.55 µM; SI-MTT = 70.12 to >357.14) or cotreatment (EC50 = 34.69 nM to 7.52 µM; SI-MTT = 5.24 to > 1,441.33) settings. All of the compounds tested inhibited viral genome replication and gene transcription, and none of them affected host cellular RNA polymerase II activities. The antiviral activity of the eight identified compounds against BIRFLU was further confirmed with seasonal IAVs (A/California/04/2009 H1N1 and A/Wyoming/3/2003 H3N2) and an IBV (B/Brisbane/60/2008, Victoria lineage), demonstrating their broad-spectrum prophylactic and therapeutic activity against currently circulating influenza viruses in humans. Together, our results identified a new set of antiviral compounds for the potential treatment of influenza viral infections.IMPORTANCE Influenza viruses are highly contagious pathogens and are a major threat to human health. Vaccination remains the most effective tool to protect humans against influenza infection. However, vaccination does not always guarantee complete protection against drifted or, more noticeably, shifted influenza viruses. Although U.S. Food and Drug Administration (FDA) drugs are approved for the treatment of influenza infections, influenza viruses resistant to current FDA antivirals have been reported and continue to emerge. Therefore, there is an urgent need to find novel antivirals for the treatment of influenza viral infections in humans, a search that could be expedited by repurposing currently approved drugs. In this study, we assessed the influenza antiviral activity of 10 compounds previously shown to inhibit mammarenavirus infection. Among them, eight drugs showed antiviral activities, providing a new battery of drugs that could be used for the treatment of influenza infections.

The Influence of Simulated Sunlight on the Inactivation of Influenza Virus in Aerosols.

BACKGROUND: Environmental parameters, including sunlight levels, are known to affect the survival of many microorganisms in aerosols. However, the impact of sunlight on the survival of influenza virus in aerosols has not been previously quantified. METHODS: The present study examined the influence of simulated sunlight on the survival of influenza virus in aerosols at both 20% and 70% relative humidity using an environmentally controlled rotating drum aerosol chamber. RESULTS: Measured decay rates were dependent on the level of simulated sunlight, but they were not significantly different between the 2 relative humidity levels tested. In darkness, the average decay constant was 0.02 ± 0.06 min-1, equivalent to a half-life of 31.6 minutes. However, at full intensity simulated sunlight, the mean decay constant was 0.29 ± 0.09 min-1, equivalent to a half-life of approximately 2.4 minutes. CONCLUSIONS: These results are consistent with epidemiological findings that sunlight levels are inversely correlated with influenza transmission, and they can be used to better understand the potential for the virus to spread under varied environmental conditions.

Ultraviolet germicidal irradiation of influenza-contaminated N95 filtering facepiece respirators.

BACKGROUND: Safe and effective decontamination and reuse of N95 filtering facepiece respirators (FFRs) has the potential to significantly extend FFR holdings, mitigating a potential shortage due to an influenza pandemic or other pandemic events. Ultraviolet germicidal irradiation (UVGI) has been shown to be effective for decontaminating influenza-contaminated FFRs. This study aims to build on past research by evaluating the UVGI decontamination efficiency of influenza-contaminated FFRs in the presence of soiling agents using an optimized UVGI dose. METHODS: Twelve samples each of 15 N95 FFR models were contaminated with H1N1 influenza (facepiece and strap), then covered with a soiling agent-artificial saliva or artificial skin oil. For each soiling agent, 3 contaminated FFRs were treated with 1 J/cm2 UVGI for approximately 1 minute, whereas 3 other contaminated FFRs remained untreated. All contaminated surfaces were cut out and virus extracted. Viable influenza was quantified using a median tissue culture infectious dose assay. RESULTS: Significant reductions (≥3 log) in influenza viability for both soiling conditions were observed on facepieces from 12 of 15 FFR models and straps from 7 of 15 FFR models. CONCLUSIONS: These data suggest that FFR decontamination and reuse using UVGI can be effective. Implementation of a UVGI method will require careful consideration of FFR model, material type, and design.

Extermination of influenza virus H1N1 by a new visible-light-induced photocatalyst under fluorescent light.

A new visible-light-induced photocatalyst based on several transition metals (iron, magnesium and manganese)-loaded TiO2 was evaluated for its anti-viral activity with influenza virus H1N1. Under a fluorescent lamp of 1000 lx, λ > 410 nm, the virus was eradicated to more than 99% within 30 min. Since this photocatalyst can be used for coating plastics, wall papers and walls, it would be desirable to use this photocatalyst to reduce viral transmission via droplets and aerosols as well as surface contact for disinfection.

Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases.

Airborne-mediated microbial diseases such as influenza and tuberculosis represent major public health challenges. A direct approach to prevent airborne transmission is inactivation of airborne pathogens, and the airborne antimicrobial potential of UVC ultraviolet light has long been established; however, its widespread use in public settings is limited because conventional UVC light sources are both carcinogenic and cataractogenic. By contrast, we have previously shown that far-UVC light (207-222 nm) efficiently inactivates bacteria without harm to exposed mammalian skin. This is because, due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer (non living) layers of human skin or eye; however, because bacteria and viruses are of micrometer or smaller dimensions, far-UVC can penetrate and inactivate them. We show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm2 of 222-nm light inactivating >95% of aerosolized H1N1 influenza virus. Continuous very low dose-rate far-UVC light in indoor public locations is a promising, safe and inexpensive tool to reduce the spread of airborne-mediated microbial diseases.

Measuring influenza RNA quantity after prolonged storage or multiple freeze/thaw cycles.

In this study, we aim to determine what effects prolonged storage and repeated freeze/thaw cycles have on the stability of influenza A(H1N1)pdm09 (influenza A/H1N1)RNA. Cloned influenza A/H1N1 RNA transcripts were serially diluted from 8.0-1.0 log10 copies/µl. RT-qPCR was used to measure RNA loss in transcripts stored at -80°C, -20°C, 4°C and 25°C for up to 84days or transcripts undergoing a total of 10 freeze/thaw cycles. Viral load was measured in clinical specimens stored at-80°C for three years (n=89 influenza A RNA extracts; n=35 primary specimens) and in 10 clinical specimens from the 2015/2016 influenza season that underwent 7 freeze/thaw cycles. RNA stored at -80°C, -20°C, 4°C and 25°C is stable for up to 56, 56, 21, and 7days respectively or up to 9 freeze/thaw cycles when stored at -80°C. There is no difference in viral load in clinical specimens that have been stored for up to three years at -80°C if they are re-extracted. Similarly, clinical specimens undergoing up to 7 freeze/thaw cycles are stable if they are re-extracted between cycles. Influenza specimens can be stored for up to three years at -80°C or undergo up to 7 freeze/thaw cycles without loss of RNA quantity if re-extracted.

Effectiveness of hydrogen peroxide and electron-beam irradiation treatment for removal and inactivation of viruses in equine-derived xenografts.

Bone grafting is a common procedure for bone reconstruction in dentistry, orthopedics, and neurosurgery. A wide range of grafts are currently used, and xenografts are regarded as an interesting alternative to autogenous bone because all mammals share the same bone mineral component composition and morphology. Antigens must be eliminated from bone grafts derived from animal tissues in order to make them biocompatible. Moreover, the processing method must also safely inactivate and/or remove viruses or other potential infectious agents. This study assessed the efficacy of two steps applied in manufacturing some equine-derived xenografts: hydrogen-peroxide and e-beam sterilization treatments for inactivation and removal of viruses in equine bone granules (cortical and cancellous) and collagen and pericardium membranes. Viruses belonging to three different human viral species (Herpes simplex virus type 1, Coxsackievirus B1, and Influenzavirus type A H1N1) were selected and used to spike semi-processed biomaterials. For each viral species, the tissue culture infective dose (TCID50) on cell lines and the number of genome copies through qPCR were assessed. Both treatments were found to be effective at virus inactivation. Considering the model viruses studied, the application of hydrogen peroxide and e-beam irradiation could also be considered effective for processing bone tissue of human origin.

Temperature-Sensitive Mutants in the Influenza A Virus RNA Polymerase: Alterations in the PA Linker Reduce Nuclear Targeting of the PB1-PA Dimer and Result in Viral Attenuation.

UNLABELLED: The influenza virus RNA-dependent RNA polymerase catalyzes genome replication and transcription within the cell nucleus. Efficient nuclear import and assembly of the polymerase subunits PB1, PB2, and PA are critical steps in the virus life cycle. We investigated the structure and function of the PA linker (residues 197 to 256), located between its N-terminal endonuclease domain and its C-terminal structured domain that binds PB1, the polymerase core. Circular dichroism experiments revealed that the PA linker by itself is structurally disordered. A large series of PA linker mutants exhibited a temperature-sensitive (ts) phenotype (reduced viral growth at 39.5°C versus 37°C/33°C), suggesting an alteration of folding kinetic parameters. The ts phenotype was associated with a reduced efficiency of replication/transcription of a pseudoviral reporter RNA in a minireplicon assay. Using a fluorescent-tagged PB1, we observed that ts and lethal PA mutants did not efficiently recruit PB1 to reach the nucleus at 39.5°C. A protein complementation assay using PA mutants, PB1, and ß-importin IPO5 tagged with fragments of the Gaussia princeps luciferase showed that increasing the temperature negatively modulated the PA-PB1 and the PA-PB1-IPO5 interactions or complex stability. The selection of revertant viruses allowed the identification of different types of compensatory mutations located in one or the other of the three polymerase subunits. Two ts mutants were shown to be attenuated and able to induce antibodies in mice. Taken together, our results identify a PA domain critical for PB1-PA nuclear import and that is a "hot spot" to engineer ts mutants that could be used to design novel attenuated vaccines. IMPORTANCE: By targeting a discrete domain of the PA polymerase subunit of influenza virus, we were able to identify a series of 9 amino acid positions that are appropriate to engineer temperature-sensitive (ts) mutants. This is the first time that a large number of ts mutations were engineered in such a short domain, demonstrating that rational design of ts mutants can be achieved. We were able to associate this phenotype with a defect of transport of the PA-PB1 complex into the nucleus. Reversion substitutions restored the ability of the complex to move to the nucleus. Two of these ts mutants were shown to be attenuated and able to produce antibodies in mice. These results are of high interest for the design of novel attenuated vaccines and to develop new antiviral drugs.

Infección por el virus H1N1: hallazgos en la radiografía simple de tórax / H1N1 virus infection: chest radiographic findings

Objetivo. Mostrar los hallazgos en la radiografía de tórax (RT) de pacientes con infección confirmada por la nueva variante del virus de la gripe A (H1N1) correlacionándolos con la historia y evolución clínica. Material y métodos. Revisión de la historia clínica y estudios radiológicos de 99 pacientes con infección por la nueva variante del virus de gripe A ingresados en dos hospitales del Servicio Cántabro de Salud. Los hallazgos en la RT fueron clasificados por el patrón parenquimatoso y la distribución de las lesiones. Resultados. De los 99 pacientes evaluados, 28 presentaron alteraciones en la RT realizada al ingresar. En estos 28 pacientes los hallazgos fueron: condensación en 19, condensación más vidrio deslustrado en 7 y vidrio deslustrado en dos; en 17 la distribución de las lesiones fue difusa, en 17 bilateral, y por campos los más afectados fueron el inferior y el medio. Trece pacientes experimentaron una progresión de las lesiones y los 7 que precisaron ventilación mecánica mostraron con mayor frecuencia en la RT del ingreso una distribución difusa de las lesiones y un mayor número de campos pulmonares afectos. Los pacientes con RT patológica fueron preferentemente varones, fumadores y presentaron disnea, dolor pleurítico y diarrea (p<0,05). Conclusión. La mayoría de los pacientes con infección por la nueva variante del virus de la gripe A no presentaron alteraciones en la RT del ingreso; sin embargo, cuando estaban presentes, el patrón predominante fue una condensación de distribución difusa, bilateral y con predominio en las bases. El derrame pleural y las adenopatías hiliares o mediastínicas fueron infrecuentes (AU)

Objective. To show the plain chest film findings in patients with confirmed infection with the new variant of the influenza A (H1N1) virus and to correlate these findings with the clinical history and evolution. Material and methods. We reviewed the clinical histories and radiological studies in 99 patients infected with the new variant of H1N1 influenza who were admitted in two Hospitals in Cantabria, Spain. Plain chest film findings were classified according to their parenchymal pattern and the distribution of the lesions. Results. Of the 99 patients evaluated, 28 had changes on the plain chest film acquired at admission. In these 28 patients, the findings were: condensation in 19, condensation and ground-glass opacities in 7, and ground-glass opacities in 2; the distribution of the lesions was diffuse in 17 patients and bilateral in 17, with the lower and middle lobes being the most frequently affected. The lesions progressed in 13 patients, and the 7 patients who required mechanical ventilation had a higher frequency of diffuse lesion distribution and more lung fields affected on the plain chest field acquired at admission. Pathological findings on plain chest films were more common in males, in smokers, and in patients who presented with shortness of breath, pleuritic pain, and diarrhea (P<0.05). Conclusion. Most patients infected with the new variant of the H1N1 virus had no alterations on the plain chest film acquired on admission; when findings were present, the predominant pattern was diffuse, bilateral condensation mainly involving the bases of the lungs. Pleural effusion and hilar or mediastinal lymph node enlargement were uncommon (AU)

Photocatalytic inactivation of influenza virus by titanium dioxide thin film.

Titanium dioxide (TiO(2)) under ultraviolet (UV) light produces a strong oxidative effect and may therefore be used as a photocatalytic disinfectant. Although many studies on the photocatalytic inactivation of bacteria have been reported, few studies have addressed virus inactivation. In the present study, we demonstrated the inactivation of influenza virus through TiO(2) photocatalysis using TiO(2) nanoparticles immobilized on a glass plate. The influences of the UV intensity, UV irradiation time and bovine serum albumin (BSA) concentration in the viral suspensions on the inactivation kinetics were investigated. Additionally, we also determined whether the International Organization for Standardization (ISO) methodology for the evaluation of antibacterial activity of TiO(2) photocatalysis could be applied to the evaluation of antiviral activity. The viral titers were dramatically reduced by the photocatalytic reaction. Even with a low intensity of UV-A (0.01 mW cm(-2)), a viral reduction of approximately 4-log(10) was observed within a short irradiation time. The viral inactivation kinetics were associated with the exposure time, the UV intensity and the BSA concentration in virus suspensions. These results show that TiO(2) photocatalysis could be used to inactivate the influenza virus. Furthermore, a minor modification of the ISO test method for anti-bacterial effects of TiO(2) photocatalysis could be useful for the evaluation of antiviral activity.

Engineering temperature sensitive live attenuated influenza vaccines from emerging viruses.

The licensed live attenuated influenza A vaccine (LAIV) in the United States is created by making a reassortant containing six internal genes from a cold-adapted master donor strain (ca A/AA/6/60) and two surface glycoprotein genes from a circulating/emerging strain (e.g., A/CA/7/09 for the 2009/2010 H1N1 pandemic). Technologies to rapidly create recombinant viruses directly from patient specimens were used to engineer alternative LAIV candidates that have genomes composed entirely of vRNAs from pandemic or seasonal strains. Multiple mutations involved in the temperature-sensitive (ts) phenotype of the ca A/AA/6/60 master donor strain were introduced into a 2009 H1N1 pandemic strain rA/New York/1682/2009 (rNY1682-WT) to create rNY1682-TS1, and additional mutations identified in other ts viruses were added to rNY1682-TS1 to create rNY1682-TS2. Both rNY1682-TS1 and rNY1682-TS2 replicated efficiently at 30°C and 33°C. However, rNY1682-TS1 was partially restricted, and rNY1682-TS2 was completely restricted at 39°C. Additionally, engineering the TS1 or TS2 mutations into a distantly related human seasonal H1N1 influenza A virus also resulted pronounced restriction of replication in vitro. Clinical symptoms and virus replication in the lungs of mice showed that although rNY1682-TS2 and the licensed FluMist(®)-H1N1pdm LAIV that was used to combat the 2009/2010 pandemic were similarly attenuated, the rNY1682-TS2 was more protective upon challenge with a virulent mutant of pandemic H1N1 virus or a heterologous H1N1 (A/PR/8/1934) virus. This study demonstrates that engineering key temperature sensitive mutations (PB1-K391E, D581G, A661T; PB2-P112S, N265S, N556D, Y658H) into the genomes of influenza A viruses attenuates divergent human virus lineages and provides an alternative strategy for the generation of LAIVs.

Aerosol susceptibility of influenza virus to UV-C light.

The person-to-person transmission of influenza virus, especially in the event of a pandemic caused by a highly virulent strain of influenza, such as H5N1 avian influenza, is of great concern due to widespread mortality and morbidity. The consequences of seasonal influenza are also substantial. Because airborne transmission appears to play a role in the spread of influenza, public health interventions should focus on preventing or interrupting this process. Air disinfection via upper-room 254-nm germicidal UV (UV-C) light in public buildings may be able to reduce influenza transmission via the airborne route. We characterized the susceptibility of influenza A virus (H1N1, PR-8) aerosols to UV-C light using a benchtop chamber equipped with a UVC exposure window. We evaluated virus susceptibility to UV-C doses ranging from 4 to 12 J/m(2) at three relative humidity levels (25, 50, and 75%). Our data show that the Z values (susceptibility factors) were higher (more susceptible) to UV-C than what has been reported previously. Furthermore, dose-response plots showed that influenza virus susceptibility increases with decreasing relative humidity. This work provides an essential scientific basis for designing and utilizing effective upper-room UV-C light installations for the prevention of the airborne transmission of influenza by characterizing its susceptibility to UV-C.

Return of inactivated whole-virus vaccine for superior efficacy.

The swine, influenza, H1N1 outbreak in 2009 highlighted the inadequacy of the currently used antibody-based vaccine strategies as a preventive measure for combating influenza pandemics. The ultimate goal for successful control of newly arising influenza outbreaks is to design a single-shot vaccine that will provide long-lasting immunity against all strains of influenza A virus. A large amount of data from animal studies has indicated that the cross-reactive cytotoxic T (Tc) cell response against conserved influenza virus epitopes may be the key immune response needed for a universal influenza vaccine. However, decades of research have shown that the development of safe T-cell-based vaccines for influenza is not an easy task. Here, I discuss the overlooked but potentially highly advantageous inactivation method, namely, γ-ray irradiation, as a mean to reach the Holy Grail of influenza vaccinology.

Effectiveness of three decontamination treatments against influenza virus applied to filtering facepiece respirators.

Filtering facepiece respirators (FFRs) are recommended for use as precautions against airborne pathogenic microorganisms; however, during pandemics demand for FFRs may far exceed availability. Reuse of FFRs following decontamination has been proposed but few reported studies have addressed the feasibility. Concerns regarding biocidal efficacy, respirator performance post decontamination, decontamination cost, and user safety have impeded adoption of reuse measures. This study examined the effectiveness of three energetic decontamination methods [ultraviolet germicidal irradiation (UVGI), microwave-generated steam, and moist heat] on two National Institute for Occupational Safety and Health-certified N95 FFRs (3M models 1860s and 1870) contaminated with H5N1. An aerosol settling chamber was used to apply virus-laden droplets to FFRs in a method designed to simulate respiratory deposition of droplets onto surfaces. When FFRs were examined post decontamination by viral culture, all three decontamination methods were effective, reducing virus load by > 4 log median tissue culture infective dose. Analysis of treated FFRs using a quantitative molecular amplification assay (quantitative real-time polymerase chain reaction) indicated that UVGI decontamination resulted in lower levels of detectable viral RNA than the other two methods. Filter performance was evaluated before and after decontamination using a 1% NaCl aerosol. As all FFRs displayed <5% penetration by 300-nm particles, no profound reduction in filtration performance was caused in the FFRs tested by exposure to virus and subsequent decontamination by the methods used. These findings indicate that, when properly implemented, these methods effectively decontaminate H5N1 on the two FFR models tested and do not drastically affect their filtering function; however, other considerations may influence decisions to reuse FFRs.

Gamma-irradiated influenza virus uniquely induces IFN-I mediated lymphocyte activation independent of the TLR7/MyD88 pathway.

BACKGROUND: We have shown previously in mice, that infection with live viruses, including influenza/A and Semliki Forest virus (SFV), induces systemic partial activation of lymphocytes, characterized by cell surface expression of CD69 and CD86, but not CD25. This partial lymphocytes activation is mediated by type-I interferons (IFN-I). Importantly, we have shown that γ-irradiated SFV does not induce IFN-I and the associated lymphocyte activation. PRINCIPAL FINDINGS: Here we report that, in contrast to SFV, γ-irradiated influenza A virus elicits partial lymphocyte activation in vivo. Furthermore, we show that when using influenza viruses inactivated by a variety of methods (UV, ionising radiation and formalin treatment), as well as commercially available influenza vaccines, only γ-irradiated influenza virus is able to trigger IFN-I-dependent partial lymphocyte activation in the absence of the TLR7/MyD88 signalling pathways. CONCLUSIONS: Our data suggest an important mechanism for the recognition of γ-irradiated influenza vaccine by cytosolic receptors, which correspond with the ability of γ-irradiated influenza virus to induce cross-reactive and cross-protective cytotoxic T cell responses.