B-Cell-Specific Diversion of Glucose Carbon Utilization Reveals a Unique Vulnerability in B Cell Malignancies.

B cell activation during normal immune responses and oncogenic transformation impose increased metabolic demands on B cells and their ability to retain redox homeostasis. While the serine/threonine-protein phosphatase 2A (PP2A) was identified as a tumor suppressor in multiple types of cancer, our genetic studies revealed an essential role of PP2A in B cell tumors. Thereby, PP2A redirects glucose carbon utilization from glycolysis to the pentose phosphate pathway (PPP) to salvage oxidative stress. This unique vulnerability reflects constitutively low PPP activity in B cells and transcriptional repression of G6PD and other key PPP enzymes by the B cell transcription factors PAX5 and IKZF1. Reflecting B-cell-specific transcriptional PPP-repression, glucose carbon utilization in B cells is heavily skewed in favor of glycolysis resulting in lack of PPP-dependent antioxidant protection. These findings reveal a gatekeeper function of the PPP in a broad range of B cell malignancies that can be efficiently targeted by small molecule inhibition of PP2A and G6PD.

Signalling input from divergent pathways subverts B cell transformation.

Malignant transformation of cells typically involves several genetic lesions, whose combined activity gives rise to cancer1. Here we analyse 1,148 patient-derived B-cell leukaemia (B-ALL) samples, and find that individual mutations do not promote leukaemogenesis unless they converge on one single oncogenic pathway that is characteristic of the differentiation stage of transformed B cells. Mutations that are not aligned with this central oncogenic driver activate divergent pathways and subvert transformation. Oncogenic lesions in B-ALL frequently mimic signalling through cytokine receptors at the pro-B-cell stage (via activation of the signal-transduction protein STAT5)2-4 or pre-B-cell receptors in more mature cells (via activation of the protein kinase ERK)5-8. STAT5- and ERK-activating lesions are found frequently, but occur together in only around 3% of cases (P = 2.2 × 10-16). Single-cell mutation and phospho-protein analyses reveal the segregation of oncogenic STAT5 and ERK activation to competing clones. STAT5 and ERK engage opposing biochemical and transcriptional programs that are orchestrated by the transcription factors MYC and BCL6, respectively. Genetic reactivation of the divergent (suppressed) pathway comes at the expense of the principal oncogenic driver and reverses transformation. Conversely, deletion of divergent pathway components accelerates leukaemogenesis. Thus, persistence of divergent signalling pathways represents a powerful barrier to transformation, while convergence on one principal driver defines a central event in leukaemia initiation. Pharmacological reactivation of suppressed divergent circuits synergizes strongly with inhibition of the principal oncogenic driver. Hence, reactivation of divergent pathways can be leveraged as a previously unrecognized strategy to enhance treatment responses.

IFITM3 functions as a PIP3 scaffold to amplify PI3K signalling in B cells.

Interferon-induced transmembrane protein 3 (IFITM3) has previously been identified as an endosomal protein that blocks viral infection1-3. Here we studied clinical cohorts of patients with B cell leukaemia and lymphoma, and identified IFITM3 as a strong predictor of poor outcome. In normal resting B cells, IFITM3 was minimally expressed and mainly localized in endosomes. However, engagement of the B cell receptor (BCR) induced both expression of IFITM3 and phosphorylation of this protein at Tyr20, which resulted in the accumulation of IFITM3 at the cell surface. In B cell leukaemia, oncogenic kinases phosphorylate IFITM3 at Tyr20, which causes constitutive localization of this protein at the plasma membrane. In a mouse model, Ifitm3-/- naive B cells developed in normal numbers; however, the formation of germinal centres and the production of antigen-specific antibodies were compromised. Oncogenes that induce the development of leukaemia and lymphoma did not transform Ifitm3-/- B cells. Conversely, the phosphomimetic IFITM3(Y20E) mutant induced oncogenic PI3K signalling and initiated the transformation of premalignant B cells. Mechanistic experiments revealed that IFITM3 functions as a PIP3 scaffold and central amplifier of PI3K signalling. The amplification of PI3K signals depends on IFITM3 using two lysine residues (Lys83 and Lys104) in its conserved intracellular loop as a scaffold for the accumulation of PIP3. In Ifitm3-/- B cells, lipid rafts were depleted of PIP3, which resulted in the defective expression of over 60 lipid-raft-associated surface receptors, and impaired BCR signalling and cellular adhesion. We conclude that the phosphorylation of IFITM3 that occurs after B cells encounter antigen induces a dynamic switch from antiviral effector functions in endosomes to a PI3K amplification loop at the cell surface. IFITM3-dependent amplification of PI3K signalling, which in part acts downstream of the BCR, is critical for the rapid expansion of B cells with high affinity to antigen. In addition, multiple oncogenes depend on IFITM3 to assemble PIP3-dependent signalling complexes and amplify PI3K signalling for malignant transformation.

Genomic insights into inherited bone marrow failure syndromes in a Korean population.

Inherited bone marrow failure syndromes (IBMFS) pose significant diagnostic challenges due to overlapping symptoms and variable expressivity, despite evolving genomic insights. The study aimed to elucidate the genomic landscape among 130 Korean patients with IBMFS. We conducted targeted next-generation sequencing (NGS) and clinical exome sequencing (CES) across the cohort, complemented by whole genome sequencing (WGS) and chromosomal microarray (CMA) in 12 and 47 cases, respectively, with negative initial results. Notably, 50% (n = 65) of our cohort achieved a genomic diagnosis. Among these, 35 patients exhibited mutations associated with classic IBMFSs (n = 33) and the recently defined IBMFS, aplastic anaemia, mental retardation and dwarfism syndrome (AmeDS, n = 2). Classic IBMFSs were predominantly detected via targeted NGS (85%, n = 28) and CES (88%, n = 29), whereas AMeDS was exclusively identified through CES. Both CMA and WGS aided in identifying copy number variations (n = 2) and mutations in previously unexplored regions (n = 2). Additionally, 30 patients were diagnosed with other congenital diseases, encompassing 13 distinct entities including inherited thrombocytopenia (n = 12), myeloid neoplasms with germline predisposition (n = 8), congenital immune disorders (n = 7) and miscellaneous genomic conditions (n = 3). CES was particularly effective in revealing these diverse diagnoses. Our findings underscore the significance of comprehensive genomic analysis in IBMFS, highlighting the need for ongoing exploration in this complex field.

Lipocalin-2 activates hepatic stellate cells and promotes nonalcoholic steatohepatitis in high-fat diet-fed Ob/Ob mice.

BACKGROUND AND AIMS: In obesity and type 2 diabetes mellitus, leptin promotes insulin resistance and contributes to the progression of NASH via activation of hepatic stellate cells (HSCs). However, the pathogenic mechanisms that trigger HSC activation in leptin-deficient obesity are still unknown. This study aimed to determine how HSC-targeting lipocalin-2 (LCN2) mediates the transition from simple steatosis to NASH. APPROACH AND RESULTS: Male wild-type (WT) and ob/ob mice were fed a high-fat diet (HFD) for 20 weeks to establish an animal model of NASH with fibrosis. Ob/ob mice were subject to caloric restriction or recombinant leptin treatment. Double knockout (DKO) mice lacking both leptin and lcn2 were also fed an HFD for 20 weeks. In addition, HFD-fed ob/ob mice were treated with gadolinium trichloride to deplete Kupffer cells. The LX-2 human HSCs and primary HSCs from ob/ob mice were used to investigate the effects of LCN2 on HSC activation. Serum and hepatic LCN2 expression levels were prominently increased in HFD-fed ob/ob mice compared with normal diet-fed ob/ob mice or HFD-fed WT mice, and these changes were closely linked to liver fibrosis and increased hepatic α-SMA/matrix metalloproteinase 9 (MMP9)/signal transducer and activator of transcription 3 (STAT3) protein levels. HFD-fed DKO mice showed a marked reduction of α-SMA protein compared with HFD-fed ob/ob mice. In particular, the colocalization of LCN2 and α-SMA was increased in HSCs from HFD-fed ob/ob mice. In primary HSCs from ob/ob mice, exogenous LCN2 treatment induced HSC activation and MMP9 secretion. By contrast, LCN2 receptor 24p3R deficiency or a STAT3 inhibitor reduced the activation and migration of primary HSCs. CONCLUSIONS: LCN2 acts as a key mediator of HSC activation in leptin-deficient obesity via α-SMA/MMP9/STAT3 signaling, thereby exacerbating NASH.

Author Correction: Metabolic gatekeeper function of B-lymphoid transcription factors.

In Fig. 3c of this Letter, the the effects of CRISPR-Cas9-mediated deletion of NR3C1, TXNIP and CNR2 in patient-derived B-lineage leukaemia cells were shown. For curves depicting NR3C1 (left graph), data s for TXNIP (middle graph) were inadvertently plotted. This figure has been corrected online, and the original Fig. 3c is shown as Supplementary Information to this Amendment for transparency. The error does not affect the conclusions of the Letter. In addition, Source Data files have been added for the Figs. 1-4 and Extended Data Figs. 1-10 of the original Letter.

PON2 subverts metabolic gatekeeper functions in B cells to promote leukemogenesis.

Unlike other cell types, developing B cells undergo multiple rounds of somatic recombination and hypermutation to evolve high-affinity antibodies. Reflecting the high frequency of DNA double-strand breaks, adaptive immune protection by B cells comes with an increased risk of malignant transformation. B lymphoid transcription factors (e.g., IKZF1 and PAX5) serve as metabolic gatekeepers by limiting glucose to levels insufficient to fuel transformation. We here identified aberrant expression of the lactonase PON2 in B cell acute lymphoblastic leukemia (B-ALL) as a mechanism to bypass metabolic gatekeeper functions. Compared to normal pre-B cells, PON2 expression was elevated in patient-derived B-ALL samples and correlated with poor clinical outcomes in pediatric and adult cohorts. Genetic deletion of Pon2 had no measurable impact on normal B cell development. However, in mouse models for BCR-ABL1 and NRASG12D-driven B-ALL, deletion of Pon2 compromised proliferation, colony formation, and leukemia initiation in transplant recipient mice. Compromised leukemogenesis resulted from defective glucose uptake and adenosine triphosphate (ATP) production in PON2-deficient murine and human B-ALL cells. Mechanistically, PON2 enabled glucose uptake by releasing the glucose-transporter GLUT1 from its inhibitor stomatin (STOM) and genetic deletion of STOM largely rescued PON2 deficiency. While not required for glucose transport, the PON2 lactonase moiety hydrolyzes the lactone-prodrug 3OC12 to form a cytotoxic intermediate. Mirroring PON2 expression levels in B-ALL, 3OC12 selectively killed patient-derived B-ALL cells but was well tolerated in transplant recipient mice. Hence, while B-ALL cells critically depend on aberrant PON2 expression to evade metabolic gatekeeper functions, PON2 lactonase activity can be leveraged as synthetic lethality to overcome drug resistance in refractory B-ALL.

Lipocalin-2 deletion attenuates lipopolysaccharide-induced acute lung inflammation via downregulating chemotaxis-related genes.

Lipocalin-2 (LCN2) is an acute phase protein used as a biomarker for acute lung injury (ALI). Although the innate immune functions of LCN2 have been studied, how LCN2 contributes to ALI induced by lipopolysaccharide (LPS) remains unknown. In this study, we investigated the effect of LCN2 deletion on LPS-induced ALI using RNA-sequencing. LPS-treated LCN2 knockout (KO) mice had a decreased histopathological score and reduced neutrophil and macrophage infiltration in lung tissue compared with LPS-treated WT mice. RNA-sequencing analysis identified 38 differentially expressed genes (DEGs), including Cxcl5, Cxcl13, Xcl1, Saa1, and Cd14. In particular, Gene Ontology analysis of DEGs revealed a significant reduction in the inflammatory response, neutrophil chemotaxis, and chemokine-mediated signaling in LPS-treated LCN2KO mice compared with LPS-treated WT mice. Thus, these results suggest that LCN2 deletion alleviates LPS-induced ALI and that LCN2 may be involved in chemotaxis-related gene expression.

Amyloid ß oligomer promotes microglial galectin-3 and astrocytic lipocalin-2 levels in the hippocampus of mice fed a high-fat diet.

Type 2 diabetes is associated with a risk factor for Alzheimer's disease (AD). Activation of glial cells, such as microglia and astrocytes, is crucial for the development of neuroinflammation in both diabetes and AD. The role of amyloid-beta oligomer (AßO) in the hippocampus of diabetic mice has been investigated; however, the effect of galectin-3 and lipocalin-2 (LCN2) on amyloid toxicity-related glial activation in diabetic mice is not known. To fill this knowledge gap, we fed mice a high-fat diet (HFD) for 20 weeks to induce a diabetic state and then injected the hippocampus with AßO. Sholl analysis of iba-1-positive microglia showed retraction of microglial ramifications in the hippocampus of HFD-fed diabetic mice. AßO treatment caused more retraction of microglial process in HFD-fed mice. In particular, microglial galectin-3 levels and astrocytic LCN2 levels were increased in the hippocampus of HFD-fed mice with AßO treatment. These findings suggest that galectin-3 and LCN2 are involved in amyloid toxicity mechanisms, especially glial activation under diabetic conditions.

Metabolic gatekeeper function of B-lymphoid transcription factors.

B-lymphoid transcription factors, such as PAX5 and IKZF1, are critical for early B-cell development, yet lesions of the genes encoding these transcription factors occur in over 80% of cases of pre-B-cell acute lymphoblastic leukaemia (ALL). The importance of these lesions in ALL has, until now, remained unclear. Here, by combining studies using chromatin immunoprecipitation with sequencing and RNA sequencing, we identify a novel B-lymphoid program for transcriptional repression of glucose and energy supply. Our metabolic analyses revealed that PAX5 and IKZF1 enforce a state of chronic energy deprivation, resulting in constitutive activation of the energy-stress sensor AMPK. Dominant-negative mutants of PAX5 and IKZF1, however, relieved this glucose and energy restriction. In a transgenic pre-B ALL mouse model, the heterozygous deletion of Pax5 increased glucose uptake and ATP levels by more than 25-fold. Reconstitution of PAX5 and IKZF1 in samples from patients with pre-B ALL restored a non-permissive state and induced energy crisis and cell death. A CRISPR/Cas9-based screen of PAX5 and IKZF1 transcriptional targets identified the products of NR3C1 (encoding the glucocorticoid receptor), TXNIP (encoding a glucose-feedback sensor) and CNR2 (encoding a cannabinoid receptor) as central effectors of B-lymphoid restriction of glucose and energy supply. Notably, transport-independent lipophilic methyl-conjugates of pyruvate and tricarboxylic acid cycle metabolites bypassed the gatekeeper function of PAX5 and IKZF1 and readily enabled leukaemic transformation. Conversely, pharmacological TXNIP and CNR2 agonists and a small-molecule AMPK inhibitor strongly synergized with glucocorticoids, identifying TXNIP, CNR2 and AMPK as potential therapeutic targets. Furthermore, our results provide a mechanistic explanation for the empirical finding that glucocorticoids are effective in the treatment of B-lymphoid but not myeloid malignancies. Thus, B-lymphoid transcription factors function as metabolic gatekeepers by limiting the amount of cellular ATP to levels that are insufficient for malignant transformation.

Performance Evaluation of Two Kinds of Rapid Antigen Test Kits for Detection of COVID-19 Infection.

BACKGROUND: The diagnostic standard for COVID-19 infection is real-time reverse transcription-polymerase chain reaction (rRT-PCR) of nasopharyngeal swab and oropharyngeal swab specimens. Rapid antigen tests are cheaper and easier to use than the rRT-PCR method. Although the COVID-19 pandemic is settling down, seasonal epi¬demic is expected. In this study, the performance of two rapid antigen test kits was evaluated based on rRT-PCR test results. METHODS: A total of 346 residual samples was tested by the PowerChek SARS-CoV-2 Real-time PCR Kit or STAN-DARD M nCoV Real-Time-Detection kit, STANDARD Q COVID-19 Ag test kit (SQ RAT), and ND COVID-19 Ag test kit (ND RAT). RESULTS: Compared to rRT-PCR as the standard method, the SQ RAT test kit yielded 77.1% sensitivity (101/131) and 100% specificity (215/215), and the ND RAT yielded 89.3% sensitivity (117/131) and 100% specificity (215/ 215). Both RATs showed sensitivity greater than 85% in samples with RdRp gene Ct value less than 25. There was a false-negative case suspected of prozone phenomenon. CONCLUSIONS: Both RATs showed significant performance, but users should beware of the prozone phenomenon.

Bacteria-derived metabolite, methylglyoxal, modulates the longevity of C. elegans through TORC2/SGK-1/DAF-16 signaling.

Gut microbes play diverse roles in modulating host fitness, including longevity; however, the molecular mechanisms underlying their mediation of longevity remain poorly understood. We performed genome-wide screens using 3,792 Escherichia coli mutants and identified 44 E. coli mutants that modulated Caenorhabditis elegans longevity. Three of these mutants modulated C. elegans longevity via the bacterial metabolite methylglyoxal (MG). Importantly, we found that low MG-producing E. coli mutants, Δhns E. coli, extended the lifespan of C. elegans through activation of the DAF-16/FOXO family transcription factor and the mitochondrial unfolded protein response (UPRmt). Interestingly, the lifespan modulation by Δhns did not require insulin/insulin-like growth factor 1 signaling (IIS) but did require TORC2/SGK-1 signaling. Transcriptome analysis revealed that Δhns E. coli activated novel class 3 DAF-16 target genes that were distinct from those regulated by IIS. Taken together, our data suggest that bacteria-derived MG modulates host longevity through regulation of the host signaling pathways rather than through nonspecific damage on biomolecules known as advanced glycation end products. Finally, we demonstrate that MG enhances the phosphorylation of hSGK1 and accelerates cellular senescence in human dermal fibroblasts, suggesting the conserved role of MG in controlling longevity across species. Together, our studies demonstrate that bacteria-derived MG is a novel therapeutic target for aging and aging-associated pathophysiology.

LCN2 deficiency ameliorates doxorubicin-induced cardiomyopathy in mice.

Doxorubicin (DOX) is an effective anticancer drug with the side effect of irreparable cardiomyopathy. Lipocalin-2 (LCN2) has been identified as an important regulator of oxidative stress and inflammation in cardiovascular disease pathophysiology. Here, we demonstrate that LCN2 deletion increases autophagic flux in the DOX-treated hearts. Mice were injected intraperitoneally six times with 30 mg/kg DOX. Echocardiography showed that DOX-treated wild-type (WT) mice had markedly weaker cardiac function compared to saline-treated WT mice. In DOX-treated LCN2 knockout (KO) mice, cardiac function was partially restored. Histological analysis showed a reduction in cardiomyocyte diameter in DOX-treated WT mice that was ameliorated in DOX-treated LCN2KO mice. Cardiac levels of phosphorylated signal transducer and activator of transcription 3, LCN2, heme oxygenase-1, and NAD (P) H dehydrogenase were markedly greater in DOX-treated WT mice than in DOX-treated LCN2KO mice. Light chain 3B (LC3B)II expression was higher in DOX-treated WT mice, but lower in DOX-treated LCN2KO mice when compared to saline-treated WT mice. Less co-localization of LC3B and lysosomal-associated membrane protein 1 was observed in DOX-treated WT mice than in DOX-treated LCN2KO mice. LCN2 co-localized with LC3B-stained cells in the DOX-treated WT mouse heart, but not in the DOX-treated LCN2KO mouse heart. These findings indicate that the cardiotoxic effect of DOX is due to autophagosome accumulation mediated by LCN2 upregulation and that LCN2 may inhibit autophagic flux, leading to DOX-induced cardiomyopathy.

Evaluation of R-FIND SARS-CoV-2 Neutralizing Antibody ELISA and FREND COVID-19 SP Rapid Fluorescence Immunoassay.

BACKGROUND: Serology testing is useful to determine the past infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: We evaluated the comparative performance of a newly developed neutralizing antibody test (R-FIND SARS-CoV-2 Neutralizing Antibody ELISA, SG Medical, Seoul, Korea) and a rapid fluorescence immunoassay (FREND™ COVID-19 SP, NanoEntek, Hwaseong, Korea) for the detection of SARS-CoV-2 spike protein antibody. They were compared with cPass™ SARS-CoV-2 Neutralization Antibody Detection Kit (Genscript Biotech, Piscataway, NJ, USA) and ADVIA Centaur SARS-CoV-2 Total (COV2T) (Siemens Healthineers, Erlangen, Germany). Forty COVID-19 samples and 80 negative samples were collected after nucleic acid tests. RESULTS: The positive percent agreement (%) of the kit in samples from 6 - 7 days, 8 - 14 days, and 15 - 45 days after symptom onset were as follows: R-FIND (83.3, 76.9, 95.2), cPass (83.3, 69.2, 90.5), FREND (66.6, 84.6, 100), and COV2T (66.6, 69.2, 76.2). The negative percent agreement (%) was 100, 97.5, 92.5, and 100 for R-FIND, cPass, FREND, and COV2T. The total agreement rate between the neutralizing antibody kits (R-FIND and cPass) was 96.7%. FREND showed high agreement with two neutralizing antibody kits (96.7% for R-FIND and 93.3% for cPass). CONCLUSIONS: R-FIND Neutralizing Antibody and FREND COVID-19 SP showed comparable detecting ability to commercial tests.

Tonicity-responsive enhancer-binding protein promotes diabetic neuroinflammation and cognitive impairment via upregulation of lipocalin-2.

BACKGROUND: Diabetic individuals have increased circulating inflammatory mediators which are implicated as underlying causes of neuroinflammation and memory deficits. Tonicity-responsive enhancer-binding protein (TonEBP) promotes diabetic neuroinflammation. However, the precise role of TonEBP in the diabetic brain is not fully understood. METHODS: We employed a high-fat diet (HFD)-only fed mice or HFD/streptozotocin (STZ)-treated mice in our diabetic mouse models. Circulating TonEBP and lipocalin-2 (LCN2) levels were measured in type 2 diabetic subjects. TonEBP haploinsufficient mice were used to investigate the role of TonEBP in HFD/STZ-induced diabetic mice. In addition, RAW 264.7 macrophages were given a lipopolysaccharide (LPS)/high glucose (HG) treatment. Using a siRNA, we examined the effects of TonEBP knockdown on RAW264 cell' medium/HG-treated mouse hippocampal HT22 cells. RESULTS: Circulating TonEBP and LCN2 levels were higher in experimental diabetic mice or type 2 diabetic patients with cognitive impairment. TonEBP haploinsufficiency ameliorated the diabetic phenotypes including adipose tissue macrophage infiltrations, neuroinflammation, blood-brain barrier leakage, and memory deficits. Systemic and hippocampal LCN2 proteins were reduced in diabetic mice by TonEBP haploinsufficiency. TonEBP (+ / -) mice had a reduction of hippocampal heme oxygenase-1 (HO-1) expression compared to diabetic wild-type mice. In particular, we found that TonEBP bound to the LCN2 promoter in the diabetic hippocampus, and this binding was abolished by TonEBP haploinsufficiency. Furthermore, TonEBP knockdown attenuated LCN2 expression in lipopolysaccharide/high glucose-treated mouse hippocampal HT22 cells. CONCLUSIONS: These findings indicate that TonEBP may promote neuroinflammation and cognitive impairment via upregulation of LCN2 in diabetic mice.

3-bit multilevel operation with accurate programming scheme in TiOx/Al2O3memristor crossbar array for quantized neuromorphic system.

As interest in artificial intelligence (AI) and relevant hardware technologies has been developed rapidly, algorithms and network structures have become significantly complicated, causing serious power consumption issues because an enormous amount of computation is required. Neuromorphic computing, a hardware AI technology with memory devices, has emerged to solve this problem. For this application, multilevel operations of synaptic devices are important to imitate floating point weight values in software AI technologies. Furthermore, weight transfer methods to desired weight targets must be arranged for off-chip training. From this point of view, we fabricate 32 × 32 memristor crossbar array and verify the 3-bit multilevel operations. The programming accuracy is verified for 3-bit quantized levels by applying a reset-voltage-control programming scheme to the fabricated TiOx/Al2O3-based memristor array. After that, a synapse composed of two differential memristors and a fully-connected neural network for modified national institute of standards and technology (MNIST) pattern recognition are constructed. The trained weights are post-training quantized in consideration of the 3-bit characteristics of the memristor. Finally, the effect of programming error on classification accuracy is verified based on the measured data, and we obtained 98.12% classification accuracy for MNIST data with the programming accuracy of 1.79% root-mean-square-error. These results imply that the proposed reset-voltage-control programming scheme can be utilized for a precise tuning, and expected to contribute for the development of a neuromorphic system capable of highly precise weight transfer.

The response of yeast vacuolar proteins: A novel rapid tool for Salmonella sp. screening.

Human health is recently affected by several factors in which food contamination is one of the most dangerous elements that damage directly on our bodies. In this study, we provided a novel approach for the rapid detection of Salmonella sp. at the molecular level using the response of Saccharomyces cerevisiae's vacuoles. First, an augmentation of vacuoles intensity was observed by confocal microscopy after treating Salmonella strains with yeast cells. Second, the vacuolar enzymes were isolated and then analyzed by two-dimensional electrophoresis for the screening of specific biomarkers. After that, various recombinant yeasts containing exclusive biomarkers were constructed by fusing these biomarkers with several fluorescent proteins. Finally, the recombinant strains showed the ability to detect Salmonella strains specifically by appropriate fluorescent signals from 20 CFU/mL after 15 Min of exposure.

Epidemiologic Linkage of COVID-19 Outbreaks at Two University-affiliated Hospitals in the Seoul Metropolitan Area in March 2020.

BACKGROUND: Coronavirus disease 2019 (COVID-19) outbreaks emerged at two university-affiliated hospitals in Seoul (hospital A) and Uijeongbu City (hospital S) in the metropolitan Seoul area in March 2020. The aim of this study was to investigate epidemiological links between the outbreaks using whole genome sequencing (WGS) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: Fifteen patients were enrolled in the study, including four non-outbreak (A1-A4) and three outbreak cases (A5-A7) in hospital A and eight cases (S1-S8) in hospital S. Patients' hospital stays, COVID-19 symptoms, and transfer history were reviewed. RNA samples were submitted for WGS and genome-wide single nucleotide variants and phylogenetic relationships were analyzed. RESULTS: The index patient (A5) in hospital A was transferred from hospital S on 26 March. Patients A6 and A7 were the family caregiver and sister, respectively, of the patient who shared a room with A5 for 4 days. Prior to transfer, A5 was at the next bed to S8 in the emergency room on 25 March. Patient S6, a professional caregiver, took care of the patient in the room next to S8's room for 5 days until 22 March and then S5 for another 3 days. WGS revealed that SARS-CoV-2 in A2, A3, and A4 belong to clades V/B.2, S/A, and G/B.1, respectively, whereas that of A5-A7 and S1-S5 are of the V/B.2.1 clade and closely clustered. In particular, SARS-CoV-2 in patients A5 and S5 showed perfect identity. CONCLUSION: WGS is a useful tool to understand epidemiology of SARS-CoV-2. It is the first study to elucidate the role of patient transfer and caregivers as links of nosocomial outbreaks of COVID-19 in multiple hospitals.

Comparison of the ASTA MicroIDSys and VITEK MS matrix-assisted laser desorption/ionization time-of-flight mass spectrometry systems for identification of clinical bacteria and yeasts.

The ASTA MicroIDSys system (ASTA, Suwon, Korea) is a newly developed Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) system for identification of microorganisms. We compared the performance of the ASTA MicroIDSys system with that of the VITEK MS system (bioMérieux, Marcy l'Etoile, France) for identifying clinical microorganisms. A total 2055 isolates including 1910 bacteria and 145 yeasts were tested. Among them, the VITEK MS correctly identified 1999 (97.3%) isolates to species level and 26 (1.3%) to the genus level. The ASTA MicroIDSys correctly identified 1988 (96.7%) isolates to species level and 28 (1.4%) to the genus level. The VITEK MS and ASTA MicroIDSys misidentified one isolate and four (0.2%) isolates, respectively, and provided no identification for 29 (1.4%) and 35 (1.7%) isolates, respectively. The performance of the ASTA MicroIDSys was comparable to that of the VITEK MS for identification of clinically relevant bacterial and yeast isolates.