Incidence and risk factors of COVID-19 in a tertiary hospital and the effectiveness of booster vaccination among health care workers: A retrospective cohort study, January 2020 to June 2022.

BACKGROUND: Health care workers (HCWs) face a higher risk of infection and may transmit pathogens to patients during a pandemic. This study aims to evaluate infection-control measures by analyzing the incidence and risk factors of COVID-19 and estimating vaccine effectiveness (VE) at a tertiary hospital in Seoul, Republic of Korea. METHODS: This study included 2,516 HCWs from January 1, 2020, to June 30, 2022. Data were analyzed to determine the incidence density and cumulative incidence; the results were compared by the age- and gender-specific standardized incidence ratios (SIR). VE was estimated with multivariate Cox proportional-hazard models as 1-adjusted hazard ratio × 100%. RESULTS: SIR indicated a lower COVID-19 risk in the hospital population than in the general Korean population (SIR, 0.81; 95% confidence interval [CI]: 0.76-0.87). Multivariate Cox analysis indicated that, compared to doctors, nonmedical service supporters and other HCWs (excluding doctors and nurses) were high-risk groups (adjusted hazard ratio [95% CI], 1.72 [1.04-2.83] and 1.76 [1.20-2.58], respectively). Compared to the outpatient unit, the emergency department was a high-risk department (1.70 [1.16-2.50]). The VE of the booster dose was 55.47%, compared to no or incomplete vaccination (95% CI: 22.63-74.37). CONCLUSIONS: Besides encouraging HCWs vaccination, effective infection-control measures should target high-risk groups and departments.

Progress, Challenges, and Opportunities in Oxide Semiconductor Devices: A Key Building Block for Applications Ranging from Display Backplanes to 3D Integrated Semiconductor Chips.

As Si has faced physical limits on further scaling down, novel semiconducting materials such as 2D transition metal dichalcogenides and oxide semiconductors (OSs) have gained tremendous attention to continue the ever-demanding downscaling represented by Moore's law. Among them, OS is considered to be the most promising alternative material because it has intriguing features such as modest mobility, extremely low off-current, great uniformity, and low-temperature processibility with conventional complementary-metal-oxide-semiconductor-compatible methods. In practice, OS has successfully replaced hydrogenated amorphous Si in high-end liquid crystal display devices and has now become a standard backplane electronic for organic light-emitting diode displays despite the short time since their invention in 2004. For OS to be implemented in next-generation electronics such as back-end-of-line transistor applications in monolithic 3D integration beyond the display applications, however, there is still much room for further study, such as high mobility, immune short-channel effects, low electrical contact properties, etc. This study reviews the brief history of OS and recent progress in device applications from a material science and device physics point of view. Simultaneously, remaining challenges and opportunities in OS for use in next-generation electronics are discussed.

Device modeling of two-steps oxygen anneal-based submicron InGaZnO back-end-of-line field-effect transistor enabling short-channel effects suppression.

Amorphous oxide semiconductor (AOS) field-effect transistors (FETs) have been integrated with complementary metal-oxide-semiconductor (CMOS) circuitry in the back end of line (BEOL) CMOS process; they are promising devices creating new and various functionalities. Therefore, it is urgent to understand the physics determining their scalability and establish a physics-based model for a robust device design of AOS BEOL FETs. However, the advantage emphasized to date has been mainly an ultralow leakage current of these devices. A device modeling that comprehensively optimizes the threshold voltage (VT), the short-channel effect (SCE), the subthreshold swing (SS), and the field-effect mobility (µFE) of short-channel AOS FETs has been rarely reported. In this study, the device modeling of two-steps oxygen anneal-based submicron indium-gallium-zinc-oxide (IGZO) BEOL FET enabling short-channel effects suppression is proposed and experimentally demonstrated. Both the process parameters determining the SCE and the device physics related to the SCE are elucidated through our modeling and a technology computer-aided design (TCAD) simulation. In addition, the procedure of extracting the model parameters is concretely supplied. Noticeably, the proposed device model and simulation framework reproduce all of the measured current-voltage (I-V), VT roll-off, and drain-induced barrier lowering (DIBL) characteristics according to the changes in the oxygen (O) partial pressure during the deposition of IGZO film, device structure, and channel length. Moreover, the results of an analysis based on the proposed model and the extracted parameters indicate that the SCE of submicron AOS FETs is effectively suppressed when the locally high oxygen-concentration region is used. Applying the two-step oxygen annealing to the double-gate (DG) FET can form this region, the beneficial effect of which is also proven through experimental results; the immunity to SCE is improved as the O-content controlled according to the partial O pressure during oxygen annealing increases. Furthermore, it is found that the essential factors in the device optimization are the subgap density of states (DOS), the oxygen content-dependent diffusion length of either the oxygen vacancy (VO) or O, and the separation between the top-gate edge and the source-drain contact hole. Our modeling and simulation results make it feasible to comprehensively optimize the device characteristic parameters, such as VT, SCE, SS, and µFE, of the submicron AOS BEOL FETs by independently controlling the lateral profile of the concentrations of VO and O in two-step oxygen anneal process.

High-Performance Thin-Film Transistor with Atomic Layer Deposition (ALD)-Derived Indium-Gallium Oxide Channel for Back-End-of-Line Compatible Transistor Applications: Cation Combinatorial Approach.

In this paper, the feasibility of an indium-gallium oxide (In2(1-x)Ga2xOy) film through combinatorial atomic layer deposition (ALD) as an alternative channel material for back-end-of-line (BEOL) compatible transistor applications is studied. The microstructure of random polycrystalline In2Oy with a bixbyite structure was converted to the amorphous phase of In2(1-x)Ga2xOy film under thermal annealing at 400 °C when the fraction of Ga is ≥29 at. %. In contrast, the enhancement in the orientation of the (222) face and subsequent grain size was observed for the In1.60Ga0.40Oy film with the intermediate Ga fraction of 20 at. %. The suitability as a channel layer was tested on the 10-nm-thick HfO2 gate oxide where the natural length was designed to meet the requirement of short channel devices with a smaller gate length (<100 nm). The In1.60Ga0.40Oy thin-film transistors (TFTs) exhibited the high field-effect mobility (µFE) of 71.27 ± 0.98 cm2/(V s), low subthreshold gate swing (SS) of 74.4 mV/decade, threshold voltage (VTH) of -0.3 V, and ION/OFF ratio of >108, which would be applicable to the logic devices such as peripheral circuit of heterogeneous DRAM. The in-depth origin for this promising performance was discussed in detail, based on physical, optical, and chemical analysis.

Relative Effectiveness of COVID-19 Vaccination in Healthcare Workers: 3-Dose Versus 2-Dose Vaccination.

The omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is known to have high infectivity and is more likely to evade vaccine immunity. However, booster vaccination is expected to strengthen cross-reactive immunity, thereby increasing the vaccine effectiveness (VE). This study aimed to evaluate the relative VE of the 3-dose (booster) vaccination compared with the 2-dose primary series vaccination in healthcare workers during omicron variant-dominant periods. During the omicron-dominant period from February 1, 2022 to February 28, 2022, a 1:1 matched case-control study was conducted. Healthcare workers with positive SARS-CoV-2 test results were classified as positive cases, whereas those with negative results served as controls. Compared with the 2-dose primary series vaccination, booster vaccination with mRNA vaccine showed moderate VE (53.1%). However, in multivariate analysis including the time elapsed after vaccination, the significant VE disappeared, reflecting the impact of recent vaccination rather than the third dose itself.

Microprocessor-Controlled Prostheses for a Bilateral Transtibial Amputee with Gait Analysis and Satisfaction: A 1-Year Followup Case Report.

Bilateral amputees are disadvantaged as they lack healthy leg support. We present the rare case of a bilateral transtibial amputee (BTA), in which we compared the first South Korean-made microprocessor-controlled prosthesis (MPA) to a conventional prosthetic ankle (CPA) with gait analysis and a patient questionnaire for long-term outcomes. A 70-year-old man presented with bilateral transtibial amputations from injury. Assessments were performed after wearing an MPA for 1 month and 1 year with three-dimensional gait analysis. Satisfaction, mobility, and pain were evaluated using the Korean version of the Prostheses Evaluation Questionnaire (K-PEQ). The spatiotemporal parameters of both sides showed increased stability from the CPA to 1 month (mMPA) and 1 year (yMPA). We observed an increased single support time, decreased step width, and almost normal stance-swing time ratio. In kinematic parameters, the ankle range of motion (ROM) was bilaterally increased at mMPA and yMPA. Unfortunately, the MPA gait showed insufficient ankle plantarflexion during the terminal stance that failed to generate push-up power. As the MPA adaptation time increased, the symmetry ratio improved to a balanced value. The questionnaire-based investigations of satisfaction, mobility, and pain revealed excellent results. The MPA proved helpful for ankle mobility in the BTA, and the questionnaire showed good satisfaction and mobility in varied terrain.

ß­catenin blockers enhance the effect of CDK4/6 inhibitors on stemness and proliferation suppression in endocrine­resistant breast cancer cells.

Wnt/ß­catenin signaling is involved in endocrine resistance and stem cell­like properties of hormone receptor­positive breast cancer cells. Palbociclib is a well­known inhibitor of cyclin­dependent kinase 4 and 6 (CDK4/6 inhibitor) that downregulates the activation of retinoblastoma protein, thereby inhibiting the cell cycle in breast cancer cells. The inhibitory effects of a combination of palbociclib and ICG­001, a ß­catenin small­molecule inhibitor, were investigated in tamoxifen­resistant breast cancer cell lines. Tamoxifen­resistant MCF­7 (TamR) cells were established by continuously exposing MCF­7 cells to tamoxifen. The characteristics associated with the stem cell­like property of cancer were assessed using western blotting, cell cycle analysis, and the mammosphere assay. The effects of the combination of palbociclib and ICG­001 were evaluated in control MCF­7 and TamR cell lines. Compared with control cells, TamR cells exhibited elevated levels of Nanog, Sox2, ALDH1, and p­STAT3, indicating stem cell­like characteristics, and elevated ß­catenin activity. TamR cells also showed significantly higher mammosphere­forming efficiency. Several markers of stem cell­like nature of TamR cells showed reduced levels upon treatment of cells with the drug combination; there was a greater reduction in the levels of these markers when the cells were treated with the combination than in the case where cells were treated with one of the drugs individually (combination index value for 25 µM palbociclib and 50 µM ICG­001 was 1.1±0.02). TamR cells treated with the palbociclib and ICG­001 combination demonstrated significantly reduced cell proliferation and mammosphere­forming efficiency compared with the cells treated with one of these drugs. The combination of the drugs could additively inhibit proliferation and suppress stem cell­like characteristics. These results suggest that ß­catenin plays a role in endocrine­resistant breast cancer; the inhibition of ß­catenin and CDK4/6 together can overcome endocrine resistance in breast cancer cells.

Atomic Layer Deposition Process-Enabled Carrier Mobility Boosting in Field-Effect Transistors through a Nanoscale ZnO/IGO Heterojunction.

Low-temperature (≤400 °C), stackable oxide semiconductors are promising as an upper transistor ingredient for monolithic three-dimensional integration. The atomic layer deposition (ALD) route provides a low-defect, high-quality semiconducting oxide channel layer and enables accurate controllability of the chemical composition and physical thickness as well as excellent step coverage on nanoscale trench structures. Here, we report a high-mobility heterojunction transistor in a ternary indium gallium zinc oxide system using the ALD technique. The heterojunction channel structure consists of a 10 nm thick indium gallium oxide (IGO) layer as an effective transporting layer and a 3 nm thick, wide band gap ZnO layer. The formation of a two-dimensional electron gas was suggested by controlling the band gap of the IGO quantum well through In/Ga ratio tailoring and reducing the physical thickness of the ZnO film. A field-effect transistor (FET) with a ZnO/In0.83Ga0.17O1.5 heterojunction channel exhibited the highest field-effect mobility of 63.2 ± 0.26 cm2/V s, a low subthreshold gate swing of 0.26 ± 0.03 V/dec, a threshold voltage of -0.84 ± 0.85 V, and an ION/OFF ratio of 9 × 108. This surpasses the performance (carrier mobility of ∼41.7 ± 1.43 cm2/V s) of an FET with a single In0.83Ga0.17O1.5 channel. Furthermore, the gate bias stressing test results indicate that FETs with a ZnO/In1-xGaxO1.5 (x = 0.25 and 0.17) heterojunction channel are much more stable than those with a single In1-xGaxO1.5 (x = 0.35, 0.25, and 0.17) channel. Relevant discussion is given in detail on the basis of chemical characterization and technological computer-aided design simulation.

Clinicopathologic Features and Molecular Characteristics of Glucose Metabolism Contributing to ¹8F-fluorodeoxyglucose Uptake in Gastrointestinal Stromal Tumors.

Fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) is useful in the preoperative diagnosis of gastrointestinal stromal tumors (GISTs); however, the molecular characteristics of glucose metabolism of GIST are unknown. We evaluated 18F-FDG uptake on preoperative PET/CT of 40 patients and analyzed the expression of glycolytic enzymes in resected GIST tissues by qRT-PCR, western blotting, and immunohistochemistry. Results of receiver operating characteristic curve analysis showed that the maximum standardized uptake value (SUVmax) cut-off value of 4.99 had a sensitivity of 89.5%, specificity was 76.2%, and accuracy of 82.5% for identifying tumors with a high risk of malignancy. We found that 18F-FDG uptake correlated positively with tumor size, risk grade, and expression levels of glucose transporter 1 (GLUT1), hexokinase 1 (HK1), and lactate dehydrogenase A (LDHA). Elevated HK and LDH activity was found in high-risk tumors. Among the isoforms of GLUT and HK, GLUT1 and HK1 expression increased with higher tumor risk grade. In addition, overexpression of glycolytic enzymes M2 isoform of pyruvate kinase (PKM2) and LDHA was observed in GISTs, especially in high-risk tumors. These results suggest that upregulation of GLUT1, HK1, PKM2, and LDHA may play an important role in GIST tumorigenesis and may be useful in the preoperative prediction of malignant potential.

The Poly-γ-d-Glutamic Acid Capsule Surrogate of the Bacillus anthracis Capsule Is a Novel Toll-Like Receptor 2 Agonist.

Bacillus anthracis is a pathogenic Gram-positive bacterium that causes a highly lethal infectious disease, anthrax. The poly-γ-d-glutamic acid (PGA) capsule is one of the major virulence factors of B. anthracis, along with exotoxins. PGA enables B. anthracis to escape phagocytosis and immune surveillance. Our previous study showed that PGA activates the human macrophage cell line THP-1 and human dendritic cells, resulting in the production of the proinflammatory cytokine interleukin-1ß (IL-1ß) (M. H. Cho et al., Infect Immun 78:387-392, 2010, http://dx.doi.org/10.1128/IAI.00956-09). Here, we investigated PGA-induced cytokine responses and related signaling pathways in mouse bone marrow-derived macrophages (BMDMs) using Bacillus licheniformis PGA as a surrogate for B. anthracis PGA. Upon exposure to PGA, BMDMs produced proinflammatory mediators, including tumor necrosis factor alpha (TNF-α), IL-6, IL-12p40, and monocyte chemoattractant protein 1 (MCP-1), in a concentration-dependent manner. PGA stimulated Toll-like receptor 2 (TLR2) but not TLR4 in Chinese hamster ovary cells expressing either TLR2 or TLR4. The ability of PGA to induce TNF-α and IL-6 was retained in TLR4(-/-) but not TLR2(-/-) BMDMs. Blocking experiments with specific neutralizing antibodies for TLR1, TLR6, and CD14 showed that TLR6 and CD14 also were necessary for PGA-induced inflammatory responses. Furthermore, PGA enhanced activation of mitogen-activated protein (MAP) kinases and nuclear factor-kappa B (NF-κB), which are responsible for expression of proinflammatory cytokines. Additionally, PGA-induced TNF-α production was abrogated not only in MyD88(-/-) BMDMs but also in BMDMs pretreated with inhibitors of MAP kinases and NF-κB. These results suggest that immune responses induced by PGA occur via TLR2, TLR6, CD14, and MyD88 through activation of MAP kinase and NF-κB pathways.

Alveolar distraction osteogenesis versus autogenous onlay bone graft for vertical augmentation of severely atrophied alveolar ridges after 12 years of long-term follow-up.

OBJECTIVE: The aim of this study was to evaluate alveolar distraction osteogenesis (ADO) and autogenous onlay bone graft (AOBG) procedures by comparing their long-term results and their ability to correct severe vertical alveolar defects for further rehabilitation. STUDY DESIGN: Fourteen patients treated with ADO and 28 patients treated with AOBG were included in this study. Radiographic measurements of alveolar bone heights over time and the implant survival and success were compared for the 2 groups. RESULTS: The vertical bone gain was 8.4 ± 2.6 mm for ADO and 6.5 ± 2.3 mm for AOBG. After a mean follow-up period of 7.1 years, there was no significant difference between the 2 groups regarding alveolar bone heights over time and implant survival and success (P > .05). The cumulative survival and success rates were 97.3%, 92.7% in the ADO group and 94.1%, 90.2% in the AOBG group, respectively. CONCLUSION: Both ADO and AOBG may be reliable and effective for ridge augmentation procedures of severe vertical alveolar bone defects and subsequent dental rehabilitation using implants.

Complete genome sequence of Bacillus anthracis H9401, an isolate from a Korean patient with anthrax.

Bacillus anthracis H9401 (NCCP 12889) is an isolate from a Korean patient with gastrointestinal anthrax. The whole genome of H9401 was sequenced. It is a circular chromosome containing 5,480 open reading frames (ORFs) and two plasmids, pXO1 containing 202 ORFs and pXO2 containing 110 ORFs. H9401 shows high pathogenicity and genome sequence similarity to Ames Ancestor.

GFP-tagged E. coli shows bacterial distribution in mouse organs: pathogen tracking using fluorescence signal.

PURPOSE: In vaccine efficacy evaluation, visualization of pathogens in whole organism at each time point would be able to reduce the consuming animals and provide the in vivo information within consistent background with identical organism. MATERIALS AND METHODS: Using IVIS spectrum whole live-animal imaging system, fluorescent intensity was optimized and visualized proportionately by concentrating Escherichia coli MC1061 strain which expresses GFP (E. coli-GFP) in BALB/C mice after injection. RESULTS: Local distribution of disseminated E. coli-GFP was traced in each organ by fluorescence. Detached organ showed more obvious fluorescent signal, and intestine showed strongest fluorescent signal. CONCLUSION: This in vivo imaging method using GFP-tagged pathogen strain suggest quantified infected pathogens by fluorescence intensity in whole animals can provide the information about the localization and distribution after infection.

Expression and characterization of an iron-containing superoxide dismutase from Burkholderia pseudomallei.

A superoxide dismutase (SOD) gene from Burkholderia pseudomallei, the causative agent of melioidosis, was cloned and expressed in Escherichia coli, and its product was functionally and physically characterized. The gene has an open-reading frame of 579 bp. The deduced amino acid sequence has 192 residues with a calculated molecular mass of ~22 kDa. Sequence comparison with other bacterial SODs showed that the protein contains typical metal-binding motifs and other Fe-SOD-conserved residues. The sequence has substantial similarity with other bacterial Fe-SOD sequences. The enzymatic activity of the expressed protein was inhibited by hydrogen peroxide but not by sodium azide or potassium cyanide, attributes that indeed are characteristic of typical bacterial Fe-SODs. Western blotting with antiserum against the recombinant Fe-SOD revealed that it is expressed in B. pseudomallei. Transformed E. coli that expressed the Fe-SOD had significantly increased SOD activity and was highly tolerant to paraquat-mediated replication inhibition, compared to transformed cells carrying an empty vector. Our results provide a basis for further biochemical characterization of the enzyme and elucidation of its role in the pathogenesis of B. pseudomallei.

Serological Correlate of Protection in Guinea Pigs for a Recombinant Protective Antigen Anthrax Vaccine Produced from Bacillus brevis.

OBJECTIVE: Recombinant protective antigen (rPA) is the active pharmaceutical ingredient of a second generation anthrax vaccine undergoing clinical trials both in Korea and the USA. By using the rPA produced from Bacillus brevis pNU212 expression system, correlations of serological immune response to anthrax protection efficacy were analyzed in a guinea pig model. METHODS: Serological responses of rPA anthrax vaccine were investigated in guinea pigs that were given single or two injections (interval of 4 weeks) of various amounts of rPA combined with aluminumhydroxide adjuvant. Guinea pigs were subsequently challenged by the intramuscular injection with 30 half-lethal doses (30LD50) of virulent Bacillus anthracis spores. Serumantibody titerswere determined by anti-PA IgGELISA and the ability of antibodies to neutralize the cytotoxicity of lethal toxin on J774A.1 cell was measured through the toxin neutralizing antibody (TNA) assay. RESULTS: To examine correlations between survival rate and antibody titers, correlation between neutralizing antibody titers and the extent of protection was determined. Toxin neutralization titers of at least 1176 were sufficient to confer protection against a dose of 30LD50 of virulent anthrax spores of the H9401 strain. Such consistency in the correlation was not observed from those antibody titers determined by ELISA. CONCLUSION: Neutralizing-antibody titers can be used as a surrogate marker.

The poly-γ-D-glutamic acid capsule of Bacillus anthracis enhances lethal toxin activity.

The poly-γ-D-glutamic acid (PGA) capsule is one of the major virulence factors of Bacillus anthracis, which causes a highly lethal infectious disease. The PGA capsule disguises B. anthracis from immune surveillance and allows its unimpeded growth in the host. The PGA capsule recently was reported to be associated with lethal toxin (LT) in the blood of experimentally infected animals (M. H. Cho, et al., Infect. Immun. 78:387-392, 2010). The effect of PGA, either alone or in combination with LT, on macrophages, which play an important role in the progression of anthrax disease, has not been thoroughly investigated. In this study, we investigated the effect of PGA on LT cytotoxicity using the mouse macrophage cell line J774A.1. PGA produced a concentration-dependent enhancement of the cytotoxicity of LT on J774A.1 cells through an enhancement in the binding and accumulation of protective antigen to its receptors. The increase of LT activity was confirmed using Western blot analysis, which showed that the combination of PGA and LT produced a greater degree of degradation of mitogen-activated protein kinase kinases and an increased level of the activation of the proform of caspase-1 to its processed form compared to the effects of LT alone. In addition, mice that received a tail vein injection of both PGA and LT had a significantly increased rate of death compared to that of mice injected with LT alone. PGA had no effect when added to cultures or administered to mice in the absence of LT. These results emphasize the importance of PGA in the pathogenesis of anthrax infection.

Optimization of culture media of pathogenic Mycoplasma hyopneumoniae by a response surface methodology.

Composition of culture medium for mass production of Mycoplasma hyopneumoniae was optimized using a response surface methodology (RSM). Initially, the influence of glucose, thallium acetate, fresh yeast extract, horse serum, and porcine serum on the production of mycoplasmal protein was assessed using a 'one factor at a time' technique. Next, factors with a significant effect, including fresh yeast extract, and horse and porcine sera, were selected for further optimization using a central composite design (CCD) of RSM. The experimental results were fitted into a second order polynomial model equation. Estimated optimal condition of the factors for maximum production of mycoplasmal protein (i.e., triple-fold increase from 0.8 mg/L produced by basal mycoplasma media to 2.5 mg/L) was 10.9% fresh yeast extract, 15% horse serum, and 31.5% porcine serum (v/v). For the optimized conditions, a 2.96 mg/L experimental result was observed, similar to the estimated optimal conditions result of the CCD.

Bacillus anthracis capsule activates caspase-1 and induces interleukin-1beta release from differentiated THP-1 and human monocyte-derived dendritic cells.

The poly-gamma-d-glutamic acid (PGA) capsule is one of the major virulence factors of Bacillus anthracis, which causes a highly lethal infection. The antiphagocytic PGA capsule disguises the bacilli from immune surveillance and allows unimpeded growth of bacilli in the host. Recently, efforts have been made to include PGA as a component of anthrax vaccine; however, the innate immune response of PGA itself has been poorly investigated. In this study, we characterized the innate immune response elicited by PGA in the human monocytic cell line THP-1, which was differentiated into macrophages with phorbol 12-myristate 13-acetate (PMA) and human monocyte-derived dendritic cells (hMoDCs). PGA capsules were isolated from the culture supernatant of either the pXO1-cured strain of B. anthracis H9401 or B. licheniformis ATCC 9945a. PGA treatment of differentiated THP-1 cells and hMoDCs led to the specific extracellular release of interleukin-1beta (IL-1beta) in a dose-dependent manner. Evaluation of IL-1beta processing by Western blotting revealed that cleaved IL-1beta increased in THP-1 cells and hMoDCs after PGA treatment. Enhanced processing of IL-1beta directly correlated with increased activation of its upstream regulator, caspase-1, also known as IL-1beta-converting enzyme (ICE). The extracellular release of IL-1beta in response to PGA was ICE dependent, since the administration of an ICE inhibitor prior to PGA treatment blocked induction of IL-1beta. These results demonstrate that B. anthracis PGA elicits IL-1beta production through activation of ICE in PMA-differentiated THP-1 cells and hMoDCs, suggesting the potential for PGA as a therapeutic target for anthrax.

Bacillus anthracis lethal toxin attenuates lipoteichoic acid-induced maturation and activation of dendritic cells through a unique mechanism.

Lethal toxin (LT), produced by the gram-positive bacterium Bacillus anthracis, was identified as a major etiologic agent causing anthrax due to its strong immunotoxicity. Gram-positive bacteria express lipoteichoic acid (LTA), which is considered as a counterpart to lipopolysaccharide (LPS) of gram-negative bacteria, but differs from LPS in the structure and function. Since dendritic cells (DCs) are essential for the appropriate initiation of immune response, we investigated the effect of LT on LTA-induced DC maturation using immature DCs prepared by differentiation of C57BL/6 mouse bone marrow cells. When immature DCs were matured with LTA in the presence of LT, the expression of representative markers for DC maturation such as CD80, CD83, and CD86 together with MHC class I and II molecules was inhibited. LT ameliorated the attenuation of endocytic capacity during DC maturation by LTA while such effect was not observed in LPS-matured DCs. Furthermore, exposure to LT resulted in a decrease in the expression of pro-inflammatory cytokines including IL-6, TNF-alpha, and IL-12p40 in LTA-stimulated DCs as in LPS-stimulated DCs. Interestingly, LT showed a minimal change in LTA-induced IL-1beta expression while LT highly enhanced the LPS-induced IL-1beta expression. Those inhibitory effects might be associated with LT interference of LTA-signaling pathways mediated through mitogen-activated protein kinases (MAPKs) since LT suppressed phosphorylation of MAPK, which was induced by LTA. Meanwhile, no change was observed in the expression of putative anthrax toxin receptors, TEM8 and CMG2, or Toll-like receptor 2. These results suggest that LT suppresses the maturation and activation of DCs stimulated with LTA, similar to the suppression in the LPS-stimulated DCs, but via a distinct mechanism.

Cloning, expression, and characterization of iron-containing superoxide dismutase from Neospora caninum.

A gene encoding superoxide dismutase (SOD) from Neospora caninum, a causative agent of neosporosis, has been cloned and its gene product functionally expressed and characterized. The gene had an open reading frame of 606 bp and deduced 201 amino acids. Sequence analysis showed that the gene had conserved metal-binding residues and conserved amino acid residues that were found in Fe-SODs. Comparison of the deduced amino acid sequence of the enzyme with previously reported Fe-SOD amino acid sequences of the other parasitic protozoans revealed significant high homology. The coding region of the N. caninum Fe-SOD was cloned and functionally expressed in Escherichia coli. Enzyme activity of the expressed protein was inhibited by hydrogen peroxide but not by sodium azide and potassium cyanide, and the enzyme showed similar biochemical properties with typical Fe-SODs of other parasitic protozoans. Southern blot analysis showed that the SOD gene appears to be present as a single-copy gene in N. caninum genome. Semiquantitative reverse transcription-polymerase chain reaction and immunoblot using antiserum raised against the purified recombinant protein showed that Fe-SOD is expressed in both developmental stages of N. caninum, i.e., in bradyzoites and tachyzoites. In an immunofluorescence assay, the enzyme was localized on the cell surface of N. caninum tachyzoites. These results suggest that Fe-SOD might be essential for the intracellular survival of N. caninum and may play an important role in the pathogenesis of the parasite by protecting the parasite from oxidative killing.