Immune Cells Are Differentially Affected by SARS-CoV-2 Viral Loads in K18-hACE2 Mice.

Viral load and the duration of viral shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are important determinants of the transmission of coronavirus disease 2019. In this study, we examined the effects of viral doses on the lung and spleen of K18-hACE2 transgenic mice by temporal histological and transcriptional analyses. Approximately, 1×105 plaque-forming units (PFU) of SARS-CoV-2 induced strong host responses in the lungs from 2 days post inoculation (dpi) which did not recover until the mice died, whereas responses to the virus were obvious at 5 days, recovering to the basal state by 14 dpi at 1×102 PFU. Further, flow cytometry showed that number of CD8+ T cells continuously increased in 1×102 PFU-virus-infected lungs from 2 dpi, but not in 1×105 PFU-virus-infected lungs. In spleens, responses to the virus were prominent from 2 dpi, and number of B cells was significantly decreased at 1×105 PFU; however, 1×102 PFU of virus induced very weak responses from 2 dpi which recovered by 10 dpi. Although the defense responses returned to normal and the mice survived, lung histology showed evidence of fibrosis, suggesting sequelae of SARS-CoV-2 infection. Our findings indicate that specific effectors of the immune response in the lung and spleen were either increased or depleted in response to doses of SARS-CoV-2. This study demonstrated that the response of local and systemic immune effectors to a viral infection varies with viral dose, which either exacerbates the severity of the infection or accelerates its elimination.

Assessing the accuracy and reliability of application-based audiometry for hearing evaluation.

Pure-tone audiometry (PTA) is the gold standard for assessing hearing loss. However, traditional PTA tests require specialized equipment, trained personnel, and a soundproof environment. Recently, smartphone-based PTA tests have been developed as an alternative method for hearing assessment. The aim of this study was to validate the accuracy and reliability of a smartphone application-based audiometry test. This study was conducted to assess the performance of application-based audiometry from November 2021 to January 2022. Pure-tone thresholds were measured using a smartphone application-based PTA test and compared with results obtained using a traditional audiometer in a sound-treated booth. The smartphone application used in this study was the "Care4Ear (Care4ear, version 1.0.6, MIJ Co., Ltd.)". Hearing thresholds less than 35 dB HL were classified as group A, 35-64 dB HL as group B, and 65 dB HL or greater as group C for the classification of hearing levels. We evaluated the accuracy of smartphone audiometry for each group and compared the results of frequency-specific hearing tests. Additionally, we examined the results of smartphone audiometry in individuals (n = 27) with asymmetric hearing loss. Seventy subjects completed both conventional audiometry and smartphone application-based hearing tests. Among the ears assessed, 55.7% were classified as group A, while 25.7% and 18.6% were classified as group B and group C, respectively. The average hearing threshold obtained from conventional pure-tone audiometry was 37.7 ± 25.2 dB HL, whereas the application-based hearing test yielded thresholds of 21.0 ± 23.0 dB HL. A significant correlation (r = 0.69, p < 0.01) was found between the average hearing thresholds obtained from the application-based and conventional pure-tone audiometry tests. The application-based test achieved a 97.4% hit rate for classifying hearing thresholds as class A, but lower rates of 22.2% for class B and 38.5% for class C. Notably, a discrepancy was observed between the hearing threshold measured by the application and the conventional audiometry for the worse ear with asymmetric hearing. The smartphone-based audiometry is a feasible method for hearing evaluation especially in persons with normal hearing. In cases of hearing loss or asymmetric hearing loss, the results of the application-based audiometry may be inaccurate, limiting its diagnostic utility.

Surgical Training Using Augmented Reality-Based Optical Head-Mounted Displays: A Pilot Study.

While the educational benefits of the modern techniques such as virtual reality (VR) or augmented reality (AR) have been suggested, there is still a lack of reports on actual surgeons' experiences. In this study, we evaluated the effectiveness of a holographic AR-based surgical training in tonsillectomy. Two otolaryngologists, 1 trainee and 1 instructor, performed 5 tonsillectomies using an AR headset (HoloLens 2, Microsoft, USA). The trainee wore the AR headset to share the surgical view through front camera while the instructor remotely accessed the device using the Microsoft Teams program and provided real-time guidance. The AR-based surgical training offered several advantages, including direct real-time guidance for the trainee and clear instructions without disturbing the surgical process. However, there were also drawbacks, such as the front camera not always matching the trainee's view and some difficulty with focusing, depending on the depth of the oral cavity. Our study suggests that AR devices are a feasible and alternative method for surgical training. With the ability to provide clear guidance, even from a distance, this technology has the potential to revolutionize surgical training in the future.

A longitudinal molecular and cellular lung atlas of lethal SARS-CoV-2 infection in K18-hACE2 transgenic mice.

BACKGROUND: The global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to approximately 500 million cases and 6 million deaths worldwide. Previous investigations into the pathophysiology of SARS-CoV-2 primarily focused on peripheral blood mononuclear cells from patients, lacking detailed mechanistic insights into the virus's impact on inflamed tissue. Existing animal models, such as hamster and ferret, do not faithfully replicate the severe SARS-CoV-2 infection seen in patients, underscoring the need for more relevant animal system-based research. METHODS: In this study, we employed single-cell RNA sequencing (scRNA-seq) with lung tissues from K18-hACE2 transgenic (TG) mice during SARS-CoV-2 infection. This approach allowed for a comprehensive examination of the molecular and cellular responses to the virus in lung tissue. FINDINGS: Upon SARS-CoV-2 infection, K18-hACE2 TG mice exhibited severe lung pathologies, including acute pneumonia, alveolar collapse, and immune cell infiltration. Through scRNA-seq, we identified 36 different types of cells dynamically orchestrating SARS-CoV-2-induced pathologies. Notably, SPP1+ macrophages in the myeloid compartment emerged as key drivers of severe lung inflammation and fibrosis in K18-hACE2 TG mice. Dynamic receptor-ligand interactions, involving various cell types such as immunological and bronchial cells, defined an enhanced TGFß signaling pathway linked to delayed tissue regeneration, severe lung injury, and fibrotic processes. INTERPRETATION: Our study provides a comprehensive understanding of SARS-CoV-2 pathogenesis in lung tissue, surpassing previous limitations in investigating inflamed tissues. The identified SPP1+ macrophages and the dysregulated TGFß signaling pathway offer potential targets for therapeutic intervention. Insights from this research may contribute to the development of innovative diagnostics and therapies for COVID-19. FUNDING: This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (2020M3A9I2109027, 2021R1A2C2004501).

Comparison of Unilateral versus Bilateral Instrumented Transforaminal Lumbar Interbody Fusion in Lumbar Degenerative Diseases: A Minimum of 5-Year Follow-Up.

Background and Objective: There is a paucity of literature comparing unilateral instrumented transforaminal lumbar interbody fusion (UITLIF) with bilateral instrumented TLIF (BITLIF) regarding radiological alignment, including the coronal balance, even though UITLIF might have asymmetric characteristics in the coronal plane. This retrospective study aimed to compare the clinical and long-term radiological outcomes of 1-level UITLIF and BITLIF in lumbar degenerative diseases (LDD) including lumbar spinal stenosis with or without spondylolisthesis (degenerative or spondylolytic). Materials and Methods: Patients who underwent 1-level UITLIF with two rectangular polyetheretherketone (PEEK) cages or BITLIF between November 2009 and June 2016 by four surgeons with ≥5 years of follow-up at a single hospital were included. We compared the clinical and radiological outcomes between the UITLIF and BITLIF. Results: In total, 63 and 111 patients who underwent UITLIF and BITLIF, respectively, were enrolled. The median follow-up was 85.55 months (range: 60-130). The UITLIF group had a significantly shorter operation time (185.0 [170.0-210.0] vs. 225.0 [200.0-265.0], p < 0.001) and lower estimated blood loss (300.0 [250.0-500.0] vs. 550.0 [400.0-800.0], p < 0.001) than the BITLIF group. Regarding the clinical outcomes, there were no significant differences in the intermittent claudication score (p = 0.495) and Kirkaldy-Willis criteria (p = 0.707) at 1 year postoperatively. The interval changes in the local coronal Cobb angle at the index level, L1-S1 lordotic angle, and coronal off-balance from the immediate postoperative radiograph to the last follow-up were not significantly different (p = 0.687, p = 0.701, and p = 0.367, respectively). Conclusions: UITLIF with two rectangular PEEK cages may provide comparable clinical outcomes and radiological longevity including coronal alignment to BITLIF in 1-level LDD. In addition, UITLIF has advantages over BITLIF in terms of operative time and blood loss.

Characterization of bipolar plates manufactured with various Pb/C ratios for unitized regenerative fuel cell system.

The weight reduction of the bipolar plate (BP) is essential for commercializing unitized regenerative fuel cells (URFCs). In order to lighten the weight of the bipolar plate, we have used Pb/C composite powder as a cost-effective primary material, which is a mixture of low-density graphite and lead. Further, varied lead-carbon weight ratios (1: 8, 1:4, 1:1, 4:1, and 8:1) were investigated for fabricating the bipolar plate by hot-pressing process adding styrene-butadiene rubber (SBR) as a binder. The specific surface area, porosity, and microstructure characteristics corresponding to the varied lead-graphite ratio of the prepared bipolar plates were studied. The relative difference in conductivity upon the compressibility of the plates is also examined. Finally, the wettability and electrochemical properties of the prepared bipolar plates were evaluated through water contact angle and cyclic voltammetry analysis.

Understanding the Residence Time Distribution in a Transient Inline Spiking System: Modeling, Experiments, and Simulations.

A transient inline spiking system is a promising tool for evaluating the performance of a virus filter in continuous operation. For better implementation of the system, we performed a systematic analysis to understand the residence time distribution (RTD) of inert tracers in the system. We aimed to understand the RTD of a salt spike, not retained onto or within the membrane pore, to focus on its mixing and spreading within the processing units. A concentrated NaCl solution was spiked into a feed stream as the spiking duration (tspike) was varied from 1 to 40 min. A static mixer was employed to mix the salt spike with the feed stream, which then passed through a single-layered nylon membrane inserted in a filter holder. The RTD curve was obtained by measuring the conductivity of the collected samples. An analytical model, the PFR-2CSTR model, was employed to predict the outlet concentration from the system. The slope and peak of the RTD curves were well-aligned with the experimental findings when τPFR = 4.3 min, τCSTR1 = 4.1 min, and τCSTR2 = 1.0 min. CFD simulations were performed to describe the flow and transport of the inert tracers through the static mixer and the membrane filter. The RTD curve spanned more than 30 min, much longer than tspike, since solutes were dispersed within processing units. The flow characteristics in each processing unit correlated with the RTD curves. Our detailed analysis of the transient inline spiking system would be helpful for implementing this protocol in continuous bioprocessing.

Establishment of multicenter COVID-19 therapeutics preclinical test system in Republic of Korea.

Throughout the recent COVID-19 pandemic, South Korea led national efforts to develop vaccines and therapeutics for SARS-CoV-2. The project proceeded as follows: 1) evaluation system setup (including Animal Biosafety Level 3 (ABSL3) facility alliance, standardized nonclinical evaluation protocol, and laboratory information management system), 2) application (including committee review and selection), and 3) evaluation (including expert judgment and reporting). After receiving 101 applications, the selection committee reviewed pharmacokinetics, toxicity, and efficacy data and selected 32 final candidates. In the nonclinical efficacy test, we used golden Syrian hamsters and human angiotensin-converting enzyme 2 transgenic mice under a cytokeratin 18 promoter to evaluate mortality, clinical signs, body weight, viral titer, neutralizing antibody presence, and histopathology. These data indicated eight new drugs and one repositioned drug having significant efficacy for COVID-19. Three vaccine and four antiviral drugs exerted significant protective activities against SARS-CoV-2 pathogenesis. Additionally, two anti-inflammatory drugs showed therapeutic effects on lung lesions and weight loss through their mechanism of action but did not affect viral replication. Along with systematic verification of COVID-19 animal models through large-scale studies, our findings suggest that ABSL3 multicenter alliance and nonclinical evaluation protocol standardization can promote reliable efficacy testing against COVID-19, thus expediting medical product development.

Manipulating wettability of catalytic surface for improving ammonia production from electrochemical nitrogen reduction.

An electrochemical nitrogen reduction reaction (ENRR) is considered a promising alternative for the traditional Haber-Bosch process. In this study, we present a method for improving the ENRR by controlling the wettability of the catalyst surface, suppressing the hydrogen evolution reaction (HER) while facilitating N2 adsorption. Reduced-graphene oxide (rGO) with a hydrophobic surface property and a contact angle (C.A.) of 59° was synthesized through a high-density atmospheric plasma deposition. Two other hydrophilic and superhydrophobic surfaces with a C.A. of 15° and 150° were developed through additional argon plasma and heat treatment of as-deposited rGO, respectively. The ENRR results showed that the ammonia yield and Faradaic efficiency tended to increase with increasing hydrophobicity. Electrochemical measurements reveal that superhydrophobic rGO achieves a higher Faradaic efficiency (5.73 %) at -0.1 V (vs RHE) and a higher NH3 yield (9.77 µg h-1 cm-2) at -0.4 V (vs RHE) in a 0.1 M KOH electrolyte. In addition, the computational fluid dynamics simulation confirmed that the amount of time the N2 gas remains on the surface could increase by improving the hydrophobicity of the catalytic surface. This study inspires the development of the rGO electrocatalyst through surface wettability modification for boosting ammonia electrosynthesis.

Corrigendum: Mouse models of lung-specific SARS-CoV-2 infection with moderate pathological traits.

[This corrects the article DOI: 10.3389/fimmu.2022.1055811.].

Mouse models of lung-specific SARS-CoV-2 infection with moderate pathological traits.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) has been a global health concern since 2019. The viral spike protein infects the host by binding to angiotensin-converting enzyme 2 (ACE2) expressed on the cell surface, which is then processed by type II transmembrane serine protease. However, ACE2 does not react to SARS-CoV-2 in inbred wild-type mice, which poses a challenge for preclinical research with animal models, necessitating a human ACE2 (hACE2)-expressing transgenic mouse model. Cytokeratin 18 (K18) promoter-derived hACE2 transgenic mice [B6.Cg-Tg(K18-ACE2)2Prlmn/J] are widely used for research on SARS-CoV-1, MERS-CoV, and SARS-CoV-2. However, SARS-CoV-2 infection is lethal at ≥105 PFU and SARS-CoV-2 target cells are limited to type-1 alveolar pneumocytes in K18-hACE2 mice, making this model incompatible with infections in the human lung. Hence, we developed lung-specific SARS-CoV-2 infection mouse models with surfactant protein B (SFTPB) and secretoglobin family 1a member 1 (Scgb1a1) promoters. After inoculation of 105 PFU of SARS-CoV-2 to the K18-hACE2, SFTPB-hACE2, and SCGB1A1-hACE2 models, the peak viral titer was detected at 2 days post-infection and then gradually decreased. In K18-hACE2 mice, the body temperature decreased by approximately 10°C, body weight decreased by over 20%, and the survival rate was reduced. However, SFTPB-hACE2 and SCGB1A1-hACE2 mice showed minimal clinical signs after infection. The virus targeted type I pneumocytes in K18-hACE2 mice; type II pneumocytes in SFTPB-hACE2 mice; and club, goblet, and ciliated cells in SCGB1A1-hACE2 mice. A time-dependent increase in severe lung lesions was detected in K18-hACE2 mice, whereas mild lesions developed in SFTPB-hACE2 and SCGB1A1-hACE2 mice. Spleen, small intestine, and brain lesions developed in K18-hACE2 mice but not in SFTPB-hACE2 and SCGB1A1-hACE2 mice. These newly developed SFTPB-hACE2 and SCGB1A1-hACE2 mice should prove useful to expand research on hACE2-mediated respiratory viruses.

Temporal Transcriptome Analysis of SARS-CoV-2-Infected Lung and Spleen in Human ACE2-Transgenic Mice.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible and potentially fatal virus. So far, most comprehensive analyses encompassing clinical and transcriptional manifestation have concentrated on the lungs. Here, we confirmed evident signs of viral infection in the lungs and spleen of SARS-CoV-2-infected K18-hACE2 mice, which replicate the phenotype and infection symptoms in hospitalized humans. Seven days post viral detection in organs, infected mice showed decreased vital signs, leading to death. Bronchopneumonia due to infiltration of leukocytes in the lungs and reduction in the spleen lymphocyte region were observed. Transcriptome profiling implicated the meticulous regulation of distress and recovery from cytokine-mediated immunity by distinct immune cell types in a time-dependent manner. In lungs, the chemokine-driven response to viral invasion was highly elevated at 2 days post infection (dpi). In late infection, diseased lungs, post the innate immune process, showed recovery signs. The spleen established an even more immediate line of defense than the lungs, and the cytokine expression profile dropped at 7 dpi. At 5 dpi, spleen samples diverged into two distinct groups with different transcriptome profile and pathophysiology. Inhibition of consecutive host cell viral entry and massive immunoglobulin production and proteolysis inhibition seemed that one group endeavored to survive, while the other group struggled with developmental regeneration against consistent viral intrusion through the replication cycle. Our results may contribute to improved understanding of the longitudinal response to viral infection and development of potential therapeutics for hospitalized patients affected by SARS-CoV-2.

Comparison of the pathogenesis of SARS-CoV-2 infection in K18-hACE2 mouse and Syrian golden hamster models.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, causes life-threatening disease. This novel coronavirus enters host cells via the respiratory tract, promoting the formation of severe pulmonary lesions and systemic disease. Few animal models can simulate the clinical signs and pathology of COVID-19 patients. Diverse preclinical studies using K18-hACE2 mice and Syrian golden hamsters, which are highly permissive to SARS-CoV-2 in the respiratory tract, are emerging; however, the systemic pathogenesis and cellular tropism of these models remain obscure. We intranasally infected K18-hACE2 mice and Syrian golden hamsters with SARS-CoV-2, and compared the clinical features, pathogenesis, cellular tropism and infiltrated immune-cell subsets. In K18-hACE2 mice, SARS-CoV-2 persistently replicated in alveolar cells and caused pulmonary and extrapulmonary disease, resulting in fatal outcomes. Conversely, in Syrian golden hamsters, transient SARS-CoV-2 infection in bronchial cells caused reversible pulmonary disease, without mortality. Our findings provide comprehensive insights into the pathogenic spectrum of COVID-19 using preclinical models.

Modulation of osteogenic differentiation by Escherichia coli-derived recombinant bone morphogenetic protein-2.

Recombinant human bone morphogenetic protein-2 (rhBMP-2), a key regulator of osteogenesis, induces the differentiation of mesenchymal cells into cartilage or bone tissues. Early orthopedic and dental studies often used mammalian cell-derived rhBMP-2, especially Chinese hamster ovary (CHO) cells. However, CHO cell-derived rhBMP-2 (C-rhBMP-2) presents disadvantages such as high cost and low production yield. To overcome these problems, Escherichia coli-derived BMP-2 (E-rhBMP-2) was developed; however, the E-rhBMP-2-induced signaling pathways and gene expression profiles during osteogenesis remain unclear. Here, we investigated the E-rhBMP-2-induced osteogenic differentiation pattern in C2C12 cells and elucidated the difference in biological characteristics between E-rhBMP-2 and C-rhBMP-2 via surface plasmon resonance, western blotting, qRT-PCR, RNA-seq, and alkaline phosphatase assays. The binding affinities of E-rhBMP-2 and C-rhBMP-2 towards BMP receptors were similar, both being confirmed at the nanomolecular level. However, the phosphorylation of Smad1/5/9 at 3 h after treatment with E-rhBMP-2 was significantly lower than that on treatment with C-rhBMP-2. The expression profiles of osteogenic marker genes were similar in both the E-rhBMP-2 and C-rhBMP-2 groups, but the gene expression level in the E-rhBMP-2 group was lower than that in the C-rhBMP-2 group at each time point. Taken together, our results suggest that the osteogenic signaling pathways induced by E-rhBMP-2 and C-rhBMP-2 both follow the general Smad-signaling pathway, but the difference in intracellular phosphorylation intensity results in distinguishable transcription profiles on osteogenic marker genes and biological activities of each rhBMP-2. These findings provide an extensive understanding of the biological properties of E-rhBMP-2 and the signaling pathways during osteogenic differentiation.

Laboratory information management system for COVID-19 non-clinical efficacy trial data.

BACKGROUND: As the number of large-scale studies involving multiple organizations producing data has steadily increased, an integrated system for a common interoperable format is needed. In response to the coronavirus disease 2019 (COVID-19) pandemic, a number of global efforts are underway to develop vaccines and therapeutics. We are therefore observing an explosion in the proliferation of COVID-19 data, and interoperability is highly requested in multiple institutions participating simultaneously in COVID-19 pandemic research. RESULTS: In this study, a laboratory information management system (LIMS) approach has been adopted to systemically manage various COVID-19 non-clinical trial data, including mortality, clinical signs, body weight, body temperature, organ weights, viral titer (viral replication and viral RNA), and multiorgan histopathology, from multiple institutions based on a web interface. The main aim of the implemented system is to integrate, standardize, and organize data collected from laboratories in multiple institutes for COVID-19 non-clinical efficacy testings. Six animal biosafety level 3 institutions proved the feasibility of our system. Substantial benefits were shown by maximizing collaborative high-quality non-clinical research. CONCLUSIONS: This LIMS platform can be used for future outbreaks, leading to accelerated medical product development through the systematic management of extensive data from non-clinical animal studies.

A Case of Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma.

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is a recently described neoplasm entity that presents only in the sinonasal tract. Histologically, it displays features of both a surface-derived carcinoma and a salivary gland carcinoma, and is associated with high-risk HPV, specifically HPV type 33. Whereas majority of the cases display high-grade histologic features, HMSC paradoxically behaves in a relatively indolent fashion. It is important and meaningful to distinguish HMSC from other histopathologic mimickers as the clinical features and management are distinctive. A 64-year-old woman presented having intermittent left-side epistaxis and progressive nasal obstruction. A well-defined, solitary, friable mass with an irregular surface that easily bled upon contact was found in the posterior part of the left nasal cavity. Endoscopic excision of the tumor which was originated from left nasal septum was done and the tumor was confirmed as HMSC. After surgery, definitive radiotherapy was performed in 28 fractions. HMSC is a histopathological type that has been rarely reported so that we report this case with literature review.

The Long-Term Effects of Budesonide Nasal Irrigation in Chronic Rhinosinusitis with Asthma.

Chronic rhinosinusitis with nasal polyps (CRSwNP) in asthmatic patients has a high recurrence rate even after surgery. For this reason, oral steroids are frequently used, but their long-term use may cause side effects. The purpose of this study is to investigate the long-term effects of budesonide nasal irrigation (BNI) in CRSwNP and asthma. An analysis of 33 patients with CRSwNP and well-controlled asthma, who performed BNI for more than 12 months, was performed. We compared oral steroid and antibiotic dosages as well as nasal endoscopy scores before, and every six months after, BNI. The six-month dosages of oral steroids and antibiotics prescribed were significantly decreased at all time points after BNI compared to before BNI. When the dosages were compared at the time point immediately preceding six months, oral steroid intake decreased significantly until 12 months, and antibiotic intake decreased until 6 months. Furthermore, the endoscopic score decreased significantly until 12 months. The nasal symptom questionnaire score also significantly improved after BNI. Therefore, BNI is considered an effective treatment method that can improve subjective symptoms and objective intranasal findings while reducing oral steroid and antibiotic doses after long-term use in patients with CRSwNP accompanied by asthma.

Broad humoral and cellular immunity elicited by one-dose mRNA vaccination 18 months after SARS-CoV-2 infection.

BACKGROUND: Practical guidance is needed regarding the vaccination of coronavirus disease 2019 (COVID-19) convalescent individuals in resource-limited countries. It includes the number of vaccine doses that should be given to unvaccinated patients who experienced COVID-19 early in the pandemic. METHODS: We recruited COVID-19 convalescent individuals who received one or two doses of an mRNA vaccine within 6 or around 18 months after a diagnosis of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection. Their samples were assessed for IgG-binding or neutralizing activity and cell-mediated immune responses against SARS-CoV-2 wild-type and variants of concern. RESULTS: A total of 43 COVID-19 convalescent individuals were analyzed in the present study. The results showed that humoral and cellular immune responses against SARS-CoV-2 wild-type and variants of concern, including the Omicron variant, were comparable among patients vaccinated within 6 versus around 18 months. A second dose of vaccine did not significantly increase immune responses. CONCLUSION: One dose of mRNA vaccine should be considered sufficient to elicit a broad immune response even around 18 months after a COVID-19 diagnosis.

Effect of Colloidal Interactions and Hydrodynamic Stress on Particle Deposition in a Single Micropore.

Clogging is ubiquitous. It happens in a wide range of material processing and causes severe performance degradation or process breakdown. In this study, we investigate clogging dynamics in a single micropore by controlling the surface property of the particle and processing condition. Microfluidic observation is conducted to investigate particle deposition in a contraction microchannel where polystyrene suspension is injected as a feed solution. The particle deposition area is quantified using the images taken using a CCD camera in both upstream and downstream of the microchannel. Pressure drop across the microchannel is also measured. When the particle interaction is repulsive, the deposition occurs mostly in downstream, while an opposite tendency is identified when the particle interaction is attractive. More complex deposition characteristics are found as the flow rate is changed. Particle flux density and the ratio of lift force to colloidal force are introduced to explain the clogging dynamics. This study provides a useful insight to alleviate clogging issues by controlling the colloidal interaction and hydrodynamic stress.

Development of a transient inline spiking system for evaluating virus clearance in continuous bioprocessing-Proof of concept for virus filtration.

The development of continuous/connected bioprocesses requires new approaches for viral clearance validation, both for specific unit operations and for the overall process. In this study, we have developed a transient inline spiking system that can be used to evaluate virus clearance at distinct time points during prolonged operation of continuous bioprocesses. The proof of concept for this system was demonstrated by evaluating the viral clearance for a virus filtration step, both with and without a prefilter upstream of the virus filter. The residence time distribution was evaluated using a previously identified noninteracting fluorescent tracer, while viral clearance was evaluated from measurements of the virus titer in samples obtained downstream of the virus filter. The measured log reduction values (LRV) for ϕX174, minute virus of mice, xenotropic murine leukemia virus, and a noninfectious mock virus particle were all within 0.5 log of those obtained using a traditional batch virus challenge for both model and real-world process streams (LRV between 2.2 and 3.4 for ϕX174 using a single layer of virus filter). The results demonstrate the effectiveness of transient inline spiking to validate the virus clearance capabilities in continuous bioprocessing, an essential element for the adoption of these processes for products made using mammalian cell lines.