Small-particle Aerosol Research Articles

6770 Graves’ disease induced by COVID-19 infection in a 49 year old male

Abstract Disclosure: N. Al-hosainat: None. A. Al Najada: None. T. Salar: None. S. Iqbal: None. K. Abdel Gadir: None. Introduction: Graves’ disease is an autoimmune disease causing hyperthyroidism, characterized by elevated thyrotropin-receptor antibodies. COVID-19 infection has been increasingly reported as a trigger of thyroid illness including Graves’ disease. We present a unique case of 49-year-old patient who was diagnosed with Graves’ disease after COVID-19 infection. Case description: A 49-year-old male patient with history of prediabetes presented with complaints of tremor, fatigue, generalized itching, and unintentional weight loss (30 Ibs in 6 months). He had COVID-19 infection 3 months prior. The remainder of review of systems was negative. No family history of thyroid disease. On exam, the patient had sinus tachycardia with otherwise normal vital signs. Diffuse thyromegaly was noted along with an intermittent fine tremor of the extremities. Blood work was notable for low TSH <0.01 uIU/mL, elevated free T4 (3.4 ng/dL), free T3 (17.6ng/dL), and TSH receptor antibody (12 IU/L). Thyroid ultrasound showed mild goiter with 2 nodules, one of which was TIRADS 4 and 1.5cm. This nodule was biopsied and found to be benign. Radioactive iodine uptake scan revealed homogeneous diffuse increased thyroid uptake. The diagnosis of Graves’ disease was made, and the patient was started on propranolol and methimazole with significant improvement of his symptoms and his laboratory tests normalizing. Discussion: Graves' disease is an autoimmune disease, characterized by hyperthyroidism, goiter, occasional orbitopathy and dermopathy. Caused by antibodies against thyroid-stimulating hormone receptors which stimulate thyroid hormone secretion and thyroid growth. Treatment is aimed to decrease thyroid hormone synthesis by either a Thionamide, radioiodine ablation, or surgery. Remission rates with antithyroid drugs average under 40 percent after one to two years of treatment and could exceed 80 percent after 5 to 10 years of treatment. COVID-19 is a multi-system disease, caused by SARS-CoV-2 virus, transmitted by large droplets and small particle aerosols, was declared a pandemic in 2020 and affected millions of people worldwide. There is emerging data showing the association of COVID-19 with various thyroid diseases including thyroiditis and relapse of known Graves' disease after the infection. We present a case of newly diagnosed Graves’ disease after COVID-19 infection in a patient with no personal or family history of such disease which raises the concern of autoimmune pathway activation induced by the infection. The onset of Graves’ disease after COVID-19 infection does not depend on the presence of pre-existing thyroid pathology and in this case responded well to antithyroid medication. Conclusion: COVID-19 can lead to the development of a range of medical illnesses. In patients who develop symptoms of thyrotoxicosis, Graves’ disease should be suspected, investigated, and treated appropriately Presentation: 6/3/2024

Characterization of pediatric extrathoracic aerosol deposition with air-jet dry powder inhalers

The use of air-jet dry powder inhalers (DPIs) offers a number of advantages for the administration of pharmaceutical aerosols, including the ability to achieve highly efficient and potentially targeted aerosol delivery to the lungs of children using the oral or trans-nasal routes of administration. To better plan targeted lung delivery of pharmaceutical aerosols with these inhalers, more information is needed on the extrathoracic (ET) depositional loss in pediatric subjects when using relatively small (e.g., 0.5–2 μm) particles and including oral or nasal device interfaces. The objective of this study was to implement validated computational fluid dynamics (CFD) models to characterize ET depositional loss during mouth-throat (MT) and nose-throat (NT) aerosol administration to pediatric subjects (2–10 years old) using an air-jet DPI platform across a range of initial small-particle aerosol sizes (0.41–13.65 μm) and inhalation flow rates (8–20 L/min).A new CFD model focused on small-particle aerosol depositional loss in existing pediatric airway models was developed and validated with existing in vitro data. The validated CFD model was then used to characterize depositional loss in the MT and NT regions of children using particle sizes, flow rates and interfaces consistent with air-jet DPIs.Successful validation of the CFD model for small-particle aerosol deposition was achieved through enhanced resolution of the near-wall transport conditions. Existing non-dimensional parameters were used to produce high quality single-curve deposition efficiency correlations with r2 values in the range of 0.95–0.97. A new method for predicting realistic polydisperse aerosol deposition using the developed correlations and an equivalent monodisperse particle diameter was also introduced. In conclusion, the newly developed correlations will be useful in planning the lung delivery of next-generation inhaled medications, where achieving both low ET loss and targeted airway deposition, perhaps with excipient enhanced growth technology, are critical factors.

Predicting the Airborne Transmission of Measles: Impact of Indoor Carbon Dioxide (CO2) Levels and Mitigation Strategies.

Measles is a highly contagious cause of febrile illness typically seen in young children. It is transmitted primarily through respiratory droplets and small-particle aerosols and can remain viable in the air. Despite the availability of an effective vaccine, measles remains a major global issue, particularly in regions with low vaccination rates. This study aimed to quantify the airborne transmission risk of the measles virus in various indoor environments. Using indoor carbon dioxide (CO2) levels, we estimated the probability of airborne transmission and the basic reproduction number (Ro) in four hypothetical indoor scenarios, including restaurants, mass gathering events, homes, and business meetings, based on the modified Wells-Riley model. The relationship between airborne transmission rates and indoor CO2 concentrations was visualized, with and without mask usage. Without masks, at an indoor CO2 concentration of 1,000 ppm, the airborne transmission rates were high in homes (100.0%) and business meetings (100.0%) and moderate in restaurants (45.6%) and live events (30.6%). By contrast, the Ro was high in audience-participatory live events (60.9%) and restaurants (13.2%), indicating a higher risk of cluster infections. In all indoor environmental scenarios, a positive linear relationship was found between the risk of airborne transmission and indoor CO2 levels. The risk of airborne transmission varied significantly across scenarios, which was influenced by various parameters, such as mask usage, quality of ventilation, conversation, and exposure duration. This model suggests that the risk of airborne transmission of measles can be easily predicted using a CO2 meter.

MVA-based vaccines are protective against lethal eastern equine encephalitis virus aerosol challenge in cynomolgus macaques.

MVA-based monovalent eastern equine encephalitis virus (MVA-BN-EEEV) and multivalent western, eastern, and Venezuelan equine encephalitis virus (MVA-BN-WEV) vaccines were evaluated in the cynomolgus macaque aerosol model of EEEV infection. Macaques vaccinated with two doses of 5 × 108 infectious units of the MVA-BN-EEEV or MVA-BN-WEV vaccine by the intramuscular route rapidly developed robust levels of neutralizing antibodies to EEEV that persisted at high levels until challenge at day 84 via small particle aerosol delivery with a target inhaled dose of 107 PFU of EEEV FL93-939. Robust protection was observed, with 7/8 animals receiving MVA-BN-EEEV and 100% (8/8) animals receiving MVA-BN-WEV surviving while only 2/8 mock vaccinated controls survived lethal challenge. Complete protection from viremia was afforded by both vaccines, with near complete protection from vRNA loads in tissues and any pathologic evidence of central nervous system damage. Overall, the results indicate both vaccines are effective in eliciting an immune response that is consistent with protection from aerosolized EEEV-induced disease.

No evidence for enhanced disease with human polyclonal SARS-CoV-2 antibody in the ferret model.

Since SARS-CoV-2 emerged in late 2019, it spread from China to the rest of the world. An initial concern was the potential for vaccine- or antibody-dependent enhancement (ADE) of disease as had been reported with other coronaviruses. To evaluate this, we first developed a ferret model by exposing ferrets to SARS-CoV-2 by either mucosal inoculation (intranasal/oral/ocular) or inhalation using a small particle aerosol. Mucosal inoculation caused a mild fever and weight loss that resolved quickly; inoculation via either route resulted in virus shedding detected in the nares, throat, and rectum for 7-10 days post-infection. To evaluate the potential for ADE, we then inoculated groups of ferrets intravenously with 0.1, 0.5, or 1 mg/kg doses of a human polyclonal anti-SARS-CoV-2 IgG from hyper-immunized transchromosomic bovines (SAB-185). Twelve hours later, ferrets were challenged by mucosal inoculation with SARS-CoV-2. We found no significant differences in fever, weight loss, or viral shedding after infection between the three antibody groups or the controls. Signs of pathology in the lungs were noted in infected ferrets but no differences were found between control and antibody groups. The results of this study indicate that healthy, young adult ferrets of both sexes are a suitable model of mild COVID-19 and that low doses of specific IgG in SAB-185 are unlikely to enhance the disease caused by SARS-CoV-2.

SARS-CoV-2 Aerosol and Intranasal Exposure Models in Ferrets.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the worldwide COVID-19 pandemic. Animal models are extremely helpful for testing vaccines and therapeutics and for dissecting the viral and host factors that contribute to disease severity and transmissibility. Here, we report the assessment and comparison of intranasal and small particle (~3 µm) aerosol SARS-CoV-2 exposure in ferrets. The primary endpoints for analysis were clinical signs of disease, recovery of the virus in the upper respiratory tract, and the severity of damage within the respiratory tract. This work demonstrated that ferrets were productively infected with SARS-CoV-2 following either intranasal or small particle aerosol exposure. SARS-CoV-2 infection of ferrets resulted in an asymptomatic disease course following either intranasal or small particle aerosol exposure, with no clinical signs, significant weight loss, or fever. In both aerosol and intranasal ferret models, SARS-CoV-2 replication, viral genomes, and viral antigens were detected within the upper respiratory tract, with little to no viral material detected in the lungs. The ferrets exhibited a specific IgG immune response to the SARS-CoV-2 full spike protein. Mild pathological findings included inflammation, necrosis, and edema within nasal turbinates, which correlated to positive immunohistochemical staining for the SARS-CoV-2 virus. Environmental sampling was performed following intranasal exposure of ferrets, and SARS-CoV-2 genomic material was detected on the feeders and nesting areas from days 2-10 post-exposure. We conclude that both intranasal and small particle aerosol ferret models displayed measurable parameters that could be utilized for future studies, including transmission studies and testing SARS-CoV-2 vaccines and therapeutics.

Aerosol Particle Size Influences the Infectious Dose and Disease Severity in a Golden Syrian Hamster Model of Inhalational COVID-19.

Background: Significant evidence suggests that SARS-CoV-2 can be transmitted via respiratory aerosols, which are known to vary as a function of respiratory activity. Most animal models examine disease presentation following inhalation of small-particle aerosols similar to those generated during quiet breathing or speaking. However, despite evidence that particle size can influence dose-infectivity relationships and disease presentation for other microorganisms, no studies have examined the infectivity of SARS-CoV-2 contained in larger particle aerosols similar to those produced during coughing, singing, or talking. Therefore, the aim of the present study was to assess the influence of aerodynamic diameter on the infectivity and virulence of aerosols containing SARS-CoV-2 in a hamster model of inhalational COVID-19. Methods: Dose-response relationships were assessed for two different aerosol particle size distributions, with mass median aerodynamic diameters (MMADs) of 1.3 and 5.2 μm in groups of Syrian hamsters exposed to aerosols containing SARS-CoV-2. Results: Disease was characterized by viral shedding in oropharyngeal swabs, increased respiratory rate, decreased activity, and decreased weight gain. Aerosol particle size significantly influenced the median doses to induce seroconversion and viral shedding, with both increasing ∼30-fold when the MMAD was increased. In addition, disease presentation was dose-dependent, with seroconversion and viral shedding occurring at lower doses than symptomatic disease characterized by increased respiratory rate and decreased activity. Conclusions: These results suggest that aerosol particle size may be an important factor influencing the risk of COVID-19 transmission and needs to be considered when developing animal models of disease. This result agrees with numerous previous studies with other microorganisms and animal species, suggesting that it would be generally translatable across different species. However, it should be noted that the absolute magnitude of the observed shifts in the median doses obtained with the specific particle sizes utilized herein may not be directly applicable to other species.

Pathogenesis of Aerosolized Ebola Virus Variant Makona in Nonhuman Primates.

Highly pathogenic filoviruses such as Ebola virus (EBOV) hold capacity for delivery by artificial aerosols, and thus potential for intentional misuse. Previous studies have shown that high doses of EBOV delivered by small-particle aerosol cause uniform lethality in nonhuman primates (NHPs), whereas only a few small studies have assessed lower doses in NHPs. To further characterize the pathogenesis of EBOV infection via small-particle aerosol, we challenged cohorts of cynomolgus monkeys with low doses of EBOV variant Makona, which may help define risks associated with small particle aerosol exposures. Despite using challenge doses orders of magnitude lower than previous studies, infection via this route was uniformly lethal across all cohorts. Time to death was delayed in a dose-dependent manner between aerosol-challenged cohorts, as well as in comparison to animals challenged via the intramuscular route. Here, we describe the observed clinical and pathological details including serum biomarkers, viral burden, and histopathological changes leading to death. Our observations in this model highlight the striking susceptibility of NHPs, and likely humans, via small-particle aerosol exposure to EBOV and emphasize the need for further development of diagnostics and postexposure prophylactics in the event of intentional release via deployment of an aerosol-producing device.

Natural history of nonhuman primates after conjunctival exposure to Ebola virus

Transmission of Ebola virus (EBOV) primarily occurs via contact exposure of mucosal surfaces with infected body fluids. Historically, nonhuman primate (NHP) challenge studies have employed intramuscular (i.m.) or small particle aerosol exposure, which are largely lethal routes of infection, but mimic worst-case scenarios such as a needlestick or intentional release, respectively. When exposed by more likely routes of natural infection, limited NHP studies have shown delayed onset of disease and reduced mortality. Here, we performed a series of systematic natural history studies in cynomolgus macaques with a range of conjunctival exposure doses. Challenge with 10,000 plaque forming units (PFU) of EBOV was uniformly lethal, whereas 5/6 subjects survived lower dose challenges (100 or 500 PFU). Conjunctival challenge resulted in a protracted time-to death compared to i.m. Asymptomatic infection was observed in survivors with limited detection of EBOV replication. Inconsistent seropositivity in survivors may suggest physical or natural immunological barriers are sufficient to prevent widespread viral dissemination.

Parapoxvirus-based therapy eliminates SARS-CoV-2-loaded fine aerosol and blocks viral transmission in hamster models.

Currently, it is believed that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an airborne virus, and virus-containing aerosol particles have been found concurrent with the onset of COVID-19, which may contribute to the noncontact transmission of SARS-CoV-2. Exploring agents to block SARS-CoV-2 transmission is of great importance to prevent the COVID-19 pandemic. In this study, we found that inactivated Parapoxvirus ovis (iORFV), a kind of immunomodulator, could compress the proportion of small particle aerosols exhaled by Syrian golden hamsters. Notably, the concentration of SARS-CoV-2 RNA-containing aerosol particles was significantly reduced by iORFV in the early stages after viral inoculation. Importantly, smaller aerosol particles (<4.7 μm) that carry infectious viruses were completely cleared by iORFV. Consistently, iORFV treatment completely blocked viral noncontact (aerosol) transmission. In summary, iORFV may become a repurposed agent for the prevention and control of COVID-19 by affecting viral aerosol exhalation and subsequent viral transmission.

Aerosol Survival, Disinfection and Formalin Inactivation of Nipah Virus.

Nipah virus is a relatively newly discovered emerging virus on the WHO list of priority pathogens which has the potential to cause outbreaks with high fatality rates. Whilst progress is being made in the development of animal models for evaluating vaccines and therapies, some of the more fundamental data on Nipah virus are lacking. We performed studies to generate novel information on the aerosol survival of Nipah virus and to look at the efficacy of two common disinfectants. We also performed studies to evaluate the inactivation of Nipah virus by using neutral buffered formalin. Nipah virus was relatively stable in a small particle (1–5 µm) aerosol in the dark, with it having a decay rate of 1.46%min−1. Sodium hypochlorite (at 10%) and ethanol (at 80%) reduced the titre of Nipah virus to undetectable levels. Nipah virus that was in tissue culture medium was also inactivated after 24 h in the presence of 10% formalin.

Histopathological and Immunological Findings in the Common Marmoset Following Exposure to Aerosolized SARS-CoV-2.

There is an enduring requirement to develop animal models of COVID-19 to assess the efficacy of vaccines and therapeutics that can be used to treat the disease in humans. In this study, six marmosets were exposed to a small particle aerosol (1–3 µm) of SARS-CoV-2 VIC01 that delivered the virus directly to the lower respiratory tract. Following the challenge, marmosets did not develop clinical signs, although a disruption to the normal diurnal temperature rhythm was observed in three out of six animals. Early weight loss and changes to respiratory pattern and activity were also observed, yet there was limited evidence of viral replication or lung pathology associated with infection. There was a robust innate immunological response to infection, which included an early increase in circulating neutrophils and monocytes and a reduction in the proportion of circulating T-cells. Expression of the ACE2 receptor in respiratory tissues was almost absent, but there was ubiquitous expression of TMPRSS2. The results of this study indicate that exposure of marmosets to high concentrations of aerosolised SARS-CoV-2 did not result in the development of clear, reproducible signs of COVID-19.

Exposure modality influences viral kinetics but not respiratory outcome of COVID-19 in multiple nonhuman primate species.

The novel coronavirus SARS-CoV-2 emerged in late 2019, rapidly reached pandemic status, and has maintained global ubiquity through the emergence of variants of concern. Efforts to develop animal models have mostly fallen short of recapitulating severe disease, diminishing their utility for research focusing on severe disease pathogenesis and life-saving medical countermeasures. We tested whether route of experimental infection substantially changes COVID-19 disease characteristics in two species of nonhuman primates (Macaca mulatta; rhesus macaques; RM, Chlorocebus atheiops; African green monkeys; AGM). Species-specific cohorts were experimentally infected with SARS-CoV-2 by either direct mucosal (intratracheal + intranasal) instillation or small particle aerosol in route-discrete subcohorts. Both species demonstrated analogous viral loads in all compartments by either exposure route although the magnitude and duration of viral loading was marginally greater in AGMs than RMs. Clinical onset was nearly immediate (+1dpi) in the mucosal exposure cohort whereas clinical signs and cytokine responses in aerosol exposure animals began +7dpi. Pathologies conserved in both species and both exposure modalities include pulmonary myeloid cell influx, development of pleuritis, and extended lack of regenerative capacity in the pulmonary compartment. Demonstration of conserved pulmonary pathology regardless of species and exposure route expands our understanding of how SARS-CoV-2 infection may lead to ARDS and/or functional lung damage and demonstrates the near clinical response of the nonhuman primate model for anti-fibrotic therapeutic evaluation studies.

Long-term persistence of viral RNA and inflammation in the CNS of macaques exposed to aerosolized Venezuelan equine encephalitis virus.

Venezuelan equine encephalitis virus (VEEV) is a positively-stranded RNA arbovirus of the genus Alphavirus that causes encephalitis in humans. Cynomolgus macaques are a relevant model of the human disease caused by VEEV and are useful in exploring pathogenic mechanisms and the host response to VEEV infection. Macaques were exposed to small-particle aerosols containing virus derived from an infectious clone of VEEV strain INH-9813, a subtype IC strain isolated from a human infection. VEEV-exposed macaques developed a biphasic fever after infection similar to that seen in humans. Maximum temperature deviation correlated with the inhaled dose, but fever duration did not. Neurological signs, suggestive of virus penetration into the central nervous system (CNS), were predominantly seen in the second febrile period. Electroencephalography data indicated a statistically significant decrease in all power bands and circadian index during the second febrile period that returned to normal after fever resolved. Intracranial pressure increased late in the second febrile period. On day 6 post-infection macaques had high levels of MCP-1 and IP-10 chemokines in the CNS, as well as a marked increase of T lymphocytes and activated microglia. More than four weeks after infection, VEEV genomic RNA was found in the brain, cerebrospinal fluid and cervical lymph nodes. Pro-inflammatory cytokines & chemokines, infiltrating leukocytes and pathological changes were seen in the CNS tissues of macaques euthanized at these times. These data are consistent with persistence of virus replication and/or genomic RNA and potentially, inflammatory sequelae in the central nervous system after resolution of acute VEEV disease.

Exposure Route Influences Disease Severity in the COVID-19 Cynomolgus Macaque Model.

The emergence of SARS-CoV-2 and the subsequent pandemic has highlighted the need for animal models that faithfully replicate the salient features of COVID-19 disease in humans. These models are necessary for the rapid selection, testing, and evaluation of potential medical countermeasures. Here, we performed a direct comparison of two distinct routes of SARS-CoV-2 exposure—combined intratracheal/intranasal and small particle aerosol—in two nonhuman primate species, rhesus and cynomolgus macaques. While all four experimental groups displayed very few outward clinical signs, evidence of mild to moderate respiratory disease was present on radiographs and at necropsy. Cynomolgus macaques exposed via the aerosol route also developed the most consistent fever responses and had the most severe respiratory disease and pathology. This study demonstrates that while all four models produced suitable representations of mild COVID-like illness, aerosol exposure of cynomolgus macaques to SARS-CoV-2 produced the most severe disease, which may provide additional clinical endpoints for evaluating therapeutics and vaccines.

Infiltration of inflammatory macrophages and neutrophils and widespread pyroptosis in lung drive influenza lethality in nonhuman primates.

Severe influenza kills tens of thousands of individuals each year, yet the mechanisms driving lethality in humans are poorly understood. Here we used a unique translational model of lethal H5N1 influenza in cynomolgus macaques that utilizes inhalation of small-particle virus aerosols to define mechanisms driving lethal disease. RNA sequencing of lung tissue revealed an intense interferon response within two days of infection that resulted in widespread expression of interferon-stimulated genes, including inflammatory cytokines and chemokines. Macaques with lethal disease had rapid and profound loss of alveolar macrophages (AMs) and infiltration of activated CCR2+ CX3CR1+ interstitial macrophages (IMs) and neutrophils into lungs. Parallel changes of AMs and neutrophils in bronchoalveolar lavage (BAL) correlated with virus load when compared to macaques with mild influenza. Both AMs and IMs in lethal influenza were M1-type inflammatory macrophages which expressed neutrophil chemotactic factors, while neutrophils expressed genes associated with activation and generation of neutrophil extracellular traps (NETs). NETs were prominent in lung and were found in alveolar spaces as well as lung parenchyma. Genes associated with pyroptosis but not apoptosis were increased in lung, and activated inflammatory caspases, IL-1β and cleaved gasdermin D (GSDMD) were present in bronchoalveolar lavage fluid and lung homogenates. Cleaved GSDMD was expressed by lung macrophages and alveolar epithelial cells which were present in large numbers in alveolar spaces, consistent with loss of epithelial integrity. Cleaved GSDMD colocalized with viral NP-expressing cells in alveoli, reflecting pyroptosis of infected cells. These novel findings reveal that a potent interferon and inflammatory cascade in lung associated with infiltration of inflammatory macrophages and neutrophils, elaboration of NETs and cell death by pyroptosis mediates lethal H5N1 influenza in nonhuman primates, and by extension humans. These innate pathways represent promising therapeutic targets to prevent severe influenza and potentially other primary viral pneumonias in humans.

Increased small particle aerosol transmission of B.1.1.7 compared with SARS-CoV-2 lineage A in vivo.

The major transmission route for SARS-CoV-2 is airborne. However, previous studies could not elucidate the contribution between large droplets and aerosol transmission of SARS-CoV-2 and its variants. Here, we designed and validated an optimized transmission caging setup, which allows for the assessment of aerosol transmission efficiency at various distances. At a distance of 2 m, only particles of <5 μm traversed between cages. Using this setup, we investigated the relative efficiency of aerosol transmission between the SARS-CoV-2 Alpha variant (B.1.1.7) and lineage A in Syrian hamsters. Aerosol transmission of both variants was confirmed in all sentinels after 24 h of exposure as demonstrated by respiratory virus shedding and seroconversion. Productive transmission also occurred after 1 h of exposure, highlighting the efficiency of this transmission route. Interestingly, after donors were infected with a mix of both variants, the Alpha variant outcompeted the lineage A variant in an airborne transmission chain. Overall, these data indicate that a lower infectious dose of the Alpha variant, compared to lineage A, could be sufficient for successful transmission. This highlights the continuous need to assess emerging variants and the development for pre-emptive transmission mitigation strategies.

Novel Transcriptional and Translational Biomarkers of Tularemia Vaccine Efficacy in a Mouse Inhalation Model: Proof of Concept.

Francisella tularensis subspecies tularensis (Ftt) is extremely virulent for humans when inhaled as a small particle aerosol (<5 µm). Inhalation of ≥20 viable bacteria is sufficient to initiate infection with a mortality rate ≥30%. Consequently, in the past, Ftt became a primary candidate for biological weapons development. To counter this threat, the USA developed a live vaccine strain (LVS), that showed efficacy in humans against inhalation of virulent Ftt. However, the breakthrough dose was fairly low, and protection waned with time. These weaknesses triggered extensive research for better vaccine candidates. Previously, we showed that deleting the clpB gene from virulent Ftt strain, SCHU S4, resulted in a mutant that was significantly less virulent than LVS for mice, yet better protected them from aerosol challenge with wild-type SCHU S4. To date, comprehensive searches for correlates of protection for SCHU S4 ΔclpB among molecules that are critical signatures of cell-mediated immunity, have yielded little reward. In this study we used transcriptomics analysis to expand the potential range of molecular correlates of protection induced by vaccination with SCHU S4 ΔclpB beyond the usual candidates. The results provide proof-of-concept that unusual host responses to vaccination can potentially serve as novel efficacy biomarkers for new tularemia vaccines.

Suction mask device: a simple, inexpensive, and effective method of reducing spread of aerosolized particles during endoscopic endonasal surgery in the era of COVID-19.

Aerosol-generating procedures, including endoscopic endonasal surgery (EES), are a major risk for physicians during the COVID-19 pandemic. Techniques for reducing aerosolization and risk of transmission of COVID-19 during these procedures would be valuable to the neurosurgical community. The authors aimed to simulate the generation of small-particle aerosols during EES and craniectomy in order to develop methods to reduce the spread of aerosolized particles, and to test the effectiveness of these methods. This study was performed at the Anatomical Laboratory for Visuospatial Innovations in Otolaryngology and Neurosurgery at The Ohio State University. The following two scenarios were used to measure three different particle sizes (0.3, 2.5, and 10 µm) generated: 1) drilling frontotemporal bone, simulating a craniectomy; and 2) drilling sphenoid bone, simulating an endonasal approach. A suction mask device was created with the aim of reducing particle release. The presence of particles was measured without suction, with a single Frazier tip suction in the field, and with the suction mask device in addition to the Frazier suction tip. Particles were measured 12 cm from the craniectomy or endonasal drilling region. In the absence of any aerosol-reducing devices, the number of particles measured during craniectomy was significantly higher than that generated by endonasal drilling. This was true regardless of the particle size measured (0.3 µm, p < 0.001; 2.5 µm, p < 0.001; and 10 µm, p < 0.001). The suction mask device reduced the release of particles of all sizes measured in the craniectomy simulation (0.3 µm, p < 0.001; 2.5 µm, p < 0.001; and 10 µm, p < 0.001) and particles of 0.3 µm and 2.5 µm in the single Frazier suction simulation (0.3 µm, p = 0.031; and 2.5 µm, p = 0.026). The suction mask device further reduced the release of particles of all sizes during EES simulation (0.3 µm, p < 0.001; and 2.5 µm, p < 0.001) and particles of 0.3 µm and 2.5 µm in the single Frazier suction simulation (0.3 µm, p = 0.033; and 2.5 µm, p = 0.048). Large particles (10 µm) were not detected during EES. The suction mask device is a simple and effective means of reducing aerosol release during EES, and it could potentially be used during mastoidectomies. This could be a valuable tool to reduce the risk of procedure-associated viral transmission during the COVID-19 pandemic.

Effect of Vibrating Mesh Nebulizer Aerosol Technology on the In Vitro Activity of Ribavirin Against Respiratory Syncytial Virus.

Ribavirin is an antiviral drug that for many years has been administered to the lungs by aerosolization. Despite advancements in oral delivery routes, there has been a renewed interested in delivering ribavirin via the pulmonary system in select patients and the severely ill. The vibrating mesh nebulizer was previously demonstrated to be an effective alternative to the small-particle aerosol generator in particle size, chemical makeup, and concentrations of the ribavirin before and after nebulization. However, the antiviral activity of ribavirin has never been examined. We sought to study ribavirin's activity before and after nebulization via vibrating mesh nebulizer. We grew and infected human epithelial type 2 cells and primary airway epithelial cells with respiratory syncytial virus (RSV). We then compared the antiviral effect of non-nebulized (control) and aerosolized ribavirin to untreated controls. We used traditional plaque assay and real-time polymerase chain reaction to determine the quantity of virus. Both non-nebulized (control) and nebulized ribavirin reduced the size of RSV plaques compared to untreated controls. Additionally, the non-nebulized and nebulized ribavirin equally inhibited RSV replication. There were no statistically significant differences between the non-nebulized and nebulized ribavirin across all time points. The vibrating mesh nebulizer did not affect the antiviral properties of nebulized ribavirin when compared to non-nebulized drug. Our findings add supporting evidence for the use of the vibrating mesh nebulizer in the administration of inhaled ribavirin.