Infection Model Research Articles

Colistin-niclosamide-loaded nanoemulsions and nanoemulsion gels for effective therapy of colistin-resistant Salmonella infections.

Colistin (COL) is regarded as a last-resort treatment for infections by multidrug-resistant (MDR) Gram-negative bacteria. The emergence of colistin-resistant Enterobacterales poses a significant global public health concern. Our study discovered that niclosamide (NIC) reverses COL resistance in Salmonella via a checkerboard assay. However, poor solubility and bioavailability of NIC pose challenges. In this study, we prepared a self-nanoemulsifying drug delivery system (SNEDDS) co-encapsulating NIC and COL. We characterized the physicochemical properties of the resulting colistin-niclosamide-loaded nanoemulsions (COL/NIC-NEs) and colistin-niclosamide-loaded nanoemulsion gels (COL/NIC-NEGs), assessing their antibacterial efficacy in vitro and in vivo. The COL/NIC-NEs exhibited a droplet size of 19.86 nm with a zeta potential of -1.25 mV. COL/NIC-NEs have excellent stability, significantly enhancing the solubility of NIC while also demonstrating a pronounced sustained-release effect. Antimicrobial assays revealed that the MIC of COL in COL/NIC-NEs was reduced by 16-128 times compared to free COL. Killing kinetics and scanning electron microscopy confirmed enhanced antibacterial activity. Antibacterial mechanism studies reveal that the COL/NIC-NEs and COL/NIC-NEGs could enhance the bactericidal activity by damaging cell membranes, disrupting proton motive force (PMF), inhibiting multidrug efflux pump, and promoting oxidative damage. The therapeutic efficacy of the COL/NIC-NEs and COL/NIC-NEGs is further demonstrated in mouse intraperitoneal infection models with COL-resistant Salmonella. To sum up, COL/NIC-NEs and COL/NIC-NEGs are a potentially effective strategies promising against COL-resistant Salmonella infections.

Cyclic Diguanylate G-Quadruplex Inducer-Quorum Sensing Inhibitor Hybrids as Bifunctional Anti-biofilm and Anti-virulence Agents Against Pseudomonas aeruginosa.

The release of virulence factors and biofilm formation by Pseudomonas aeruginosa are pivotal drivers of its severe pathogenicity and antibiotic resistance. Based on our prior findings, cyclic di-GMP (c-di-GMP) G-quadruplex inducers are promising biofilm inhibitors and that quorum sensing systems are central regulators of virulence, we aimed to design and synthesize c-di-GMP G-quadruplex inducer-quorum sensing inhibitor hybrids. These hybrids were envisioned as bifunctional agents with both antibiofilm and antivirulence capabilities. Hybrids A7 and A11, characterized by their quinoline and 3-indole rings, emerged as potent inhibitors. They achieve this dual action by inducing c-di-GMP G-quadruplex formation and disrupting the las and pqs signaling system. Additionally, hybrids A7 and A11 attenuated virulence factors and inhibited the motility phenotypes of P. aeruginosa. Furthermore, when tested in in vivo Caenorhabditis elegans infection models, these hybrids, in combination with antibiotics such as tetracycline, improved survival rates, all while maintaining a favorable biosafety profile.

Multiplex antimicrobial activities of the self-assembled amphiphilic polypeptide β nanofiber KF-5 against vaginal pathogens

BackgroundVaginal infections caused by multidrug-resistant pathogens such as Candida albicans and Gardnerella spp. represent a significant health challenge. Current treatments often fail because of resistance and toxicity. This study aimed to synthesize and characterize a novel amphiphilic polypeptide, KF-5, and evaluate its antibacterial and antifungal activities, biocompatibility, and potential mechanisms of action.ResultsThe KF-5 peptide was synthesized via solid-phase peptide synthesis and self-assembled into nanostructures with filamentous and hydrogel-like configurations. Characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) confirmed the unique nanostructural properties of KF-5. KF-5 (125, 250, or 500 µg/ml) demonstrated potent antibacterial and antifungal activities, with significant inhibitory effects on drug-resistant Candida albicans and Gardnerella spp. (P < 0.05). In vitro assays revealed that 500 µg/ml KF-5 disrupted microbial cell membranes, increased membrane permeability, and induced lipid oxidation, leading to cell death (P < 0.05). Cytotoxicity tests revealed minimal toxicity in human vaginal epithelial cells, keratinocytes, and macrophages, with over 95% viability at high concentrations. Molecular dynamics simulations indicated that KF-5 interacts with phospholipid bilayers through electrostatic interactions, causing membrane disruption. In vivo studies using a mouse model of vaginal infection revealed that 0.5, 1, and 2 mg/ml KF-5 significantly reduced fungal burden and inflammation, and histological analysis confirmed the restoration of vaginal mucosal integrity (P < 0.01). Compared with conventional antifungal treatments such as miconazole, KF-5 exhibited superior efficacy (P < 0.01).ConclusionsKF-5 demonstrates significant potential as a safe and effective antimicrobial agent for treating vaginal infections. Its ability to disrupt microbial membranes while maintaining biocompatibility with human cells highlights its potential for clinical application. These findings provide a foundation for further development of KF-5 as a therapeutic option for combating drug-resistant infections.

A predictive model for secondary central nervous system infection after craniotomy based on machine learning

To analyze the risk factors of secondary Central nervous system infections (CNSIs) after craniotomy, and to establish an individualized predictive model for CNSIs risk. The independent risk factors were screened by univariate and multivariate logistic regression analysis. Logistic regression, naive bayes, random forest, light GBM and adaboost algorithms were used to establish predictive models for secondary CNSIs after craniotomy. The predictive model based on the Adaboost algorithm demonstrated superior prediction performance compared to the other four models. Under 5-fold cross validation, the accuracy was 0.80, the precision was 0.69, the recall was 0.85, the F1-score was 0.76, the area under the ROC curve was 0.897,and the average precision was 0.880. The top 5 variables of importance in Adaboost model were operation time, indwelling time of lumbar drainage tube, indwelling lumbar drainage tube during operation, indwelling epidural drainage tube during operation, and GCS score. In addition, Adaboost model with the best prediction performance was used for clinical verification, and the prediction results were compared with the actual occurrence of CNSIs after surgery. The results showed that the accuracy of Adaboost model in predicting CNSIs was 60%, the accuracy of Adaboost model in predicting non-CNSIS was 92%, and the overall prediction accuracy was 76%.

Bovine pulp extracellular matrix hydrogel for regenerative endodontic applications: in vitro characterization and in vivo analysis in a necrotic tooth model

BackgroundRegenerative endodontic procedures (REPs) offer the promise of restoring vitality and function to a previously necrotic and infected tooth. However, the nature of regenerated tissues following REPs remains unpredictable and uncontrollable. Decellularized extracellular matrix scaffolds have gained recent attention as scaffolds for regenerative endodontics.ObjectivesPreparation and characterization of a bovine dental pulp-derived extracellular matrix (P-ECM) hydrogel for regenerative endodontic applications. Biocompatibility and regenerative capacity of the prepared scaffold were evaluated in vivo in a canine animal model.MethodsFifteen freshly extracted bovine molar teeth were used to prepare P-ECM hydrogels following approval of the institutional review board of the faculty of dentistry, Alexandria University. Decellularization and lyophilization of the extracted pulp tissues, DNA quantification and histological examination of decellularized P-ECM were done. P-ECM hydrogel was prepared by digestion of decellularized pulps. Prepared scaffolds were evaluated for protein content and release as well as release of VEGF, bFGF, TGF-β1 and BMP2 using ELISA. Rabbit dental pulp stem cells’ (rDPSCs) viability in response to P-ECM hydrogels was performed. Finally, proof-of-concept of the regenerative capacity of P-ECM scaffolds was assessed in an infected mature canine tooth model following REPs versus blood clot (BC), injectable platelet-rich fibrin (i-PRF) or hyaluronic acid (HA). Statistical analysis was done using independent t test, the Friedman test and chi-square tests (p value ≤ 0.05).ResultsDNA was found to be below the cut-off point (50 ng/mg tissue). Histological evaluation revealed absence of nuclei, retention of glycosaminoglycans (GAGs) and collagen content, respectively. P-ECM hydrogel had a total protein content of (493.12 µg/µl) and protein release was detected up to 14 days. P-ECM hydrogel also retained VEGF, bFGF, TGF-β1 and BMP2. P-ECM hydrogel maintained the viability of rDPSCs as compared to cells cultured under control conditions. P-ECM hydrogel triggered more organized tissues compared to BC, i-PRF and HA when used in REPs for necrotic mature teeth in dogs. Periapical inflammation was significantly less in HA and P-ECM groups compared to blood-derived scaffolds.ConclusionBovine dental pulp-derived extracellular matrix (P-ECM) hydrogel scaffold retained its bioactive properties and demonstrated a promising potential in regenerative endodontic procedures compared to conventional blood-derived scaffolds.

From COVID-19 to monkeypox: a novel predictive model for emerging infectious diseases

The outbreak of emerging infectious diseases poses significant challenges to global public health. Accurate early forecasting is crucial for effective resource allocation and emergency response planning. This study aims to develop a comprehensive predictive model for emerging infectious diseases, integrating the blending framework, transfer learning, incremental learning, and the biological feature Rt to increase prediction accuracy and practicality. By transferring features from a COVID-19 dataset to a monkeypox dataset and introducing dynamically updated incremental learning techniques, the model's predictive capability in data-scarce scenarios was significantly improved. The research findings demonstrate that the blending framework performs exceptionally well in short-term (7-day) predictions. Furthermore, the combination of transfer learning and incremental learning techniques significantly enhanced the adaptability and precision, with a 91.41% improvement in the RMSE and an 89.13% improvement in the MAE. In particular, the inclusion of the Rt feature enabled the model to more accurately reflect the dynamics of disease spread, further improving the RMSE by 1.91% and the MAE by 2.17%. This study underscores the significant application potential of multimodel fusion and real-time data updates in infectious disease prediction, offering new theoretical perspectives and technical support. This research not only enriches the theoretical foundation of infectious disease prediction models but also provides reliable technical support for public health emergency responses. Future research should continue to explore integrating data from multiple sources and enhancing model generalization capabilities to further enhance the practicality and reliability of predictive tools.

Epstein-Barr virus infection induces tissue-resident memory T cells in mucosal lymphoid tissues.

EBV contributes to around 2% of all tumors worldwide. Simultaneously, more than 90% of healthy human adults persistently carry EBV without clinical symptoms. In most EBV carriers, it is thought that virus-induced tumorigenesis is prevented by cell-mediated immunity. Specifically, memory CD8+ T cells recognize EBV-infected cells during latent and lytic infection. Using a symptomatic primary infection model, similar to infectious mononucleosis (IM), we found EBV-induced CD8+ tissue resident memory T cells (TRMs) in mice with a humanized immune system. These human TRMs were preferentially established after intranasal EBV infection in nasal-associated lymphoid tissues (NALT), equivalent to tonsils, the primary site of EBV infection in humans. They expressed canonical TRM markers, including CD69, CD103, and BLIMP-1, as well as granzyme B, CD107a, and CCL5. Despite cytotoxic activity and cytokine production ex vivo, these TRMs demonstrated reduced CD27 expression and proliferation and failed to control EBV viral loads in the NALT during infection, although effector memory T cells (TEMs) controlled viral titers in spleen and blood. Overall, TRMs are established in mucosal lymphoid tissues by EBV infection, but primarily, systemic CD8+ T cell expansion seems to control viral loads in the context of IM-like infection.

Apoptosis, inflammatory and innate immune responses induced by infection with a novel goose astrovirus in goose embryonic kidney cells.

Since 2016, a highly lethal visceral gout induced by infection with the novel goose astrovirus (GoAstV) resulted in an ongoing outbreak in goslings in China, with a mortality rate ranging from 10% to 50%, and causing considerable economic losses in the goose industry. However, the pathogenesis of GoAstV and the molecular mechanism by which kidney lesions are induced by GoAstV infection are unclear. In the present study, a GEK cell infection model for GoAstV was established, and the apoptosis, inflammatory and innate immune responses induced by GoAstV were investigated in GEK cells. The results shown that the expression of proapoptotic proteins, including Bax, caspase-3, caspase-9 and cytochrome c, increased in the infection group; however, the expression of the antiapoptotic protein Bcl-2 decreased, indicating that apoptosis was induced by GoAstV infection in GEK cells. Besides, the activation of the RIG-I/MDA5 pathway and the downstream upregulation of proinflammatory cytokines, including the adapter proteins MAVS, IRF7 and NF-κB and the proinflammatory cytokines IL-6, IL-8 and TNF-α, were detected in GEK cells infected with GoAstV. In addition, GoAstV infection induces the activation of the NLPR3 pathway and further stimulates the increased production of IL-1β. In summary, the present study revealed that GoAstV infection could induce apoptosis and the activation of the RIG-I/MDA5 and NLRP3 pathways in GEK cells, as well as the massive release of proinflammatory cytokines. These results are helpful for elucidating the molecular mechanism of pathological lesions in the kidney in gout goslings infected with GoAstV and the interaction between GoAstV and the innate immune system of the host.

Numerical Simulation of SEIR Model for COVID-19 Infection

One of the most basic models in epidemiology, the SEIR (Susceptible-Exposed-Infectious-Recovered) model explains how viral infections spread through communities. This study analyzes the SEIR model's differential equations to learn more about its dynamic behaviors. This study discusses the 2019 corona virus disease (COVID-19) epidemic model using numerical methods of susceptible exposed infected recovered (SEIR). A numerical description of the notion is provided using two numerical approaches, including forward Euler and RK-4 approaches. The subplots of SEIR model are drawn by ode 45 commands. The stability of disease free equilibrium and Endemic equilibrium points are depicted. The significance of comprehending the interaction between epidemiological variables and population dynamics in developing efficient public health treatments is brought to light in this study, which investigates the consequences of these equations on the transmission and management of infectious diseases. Insights into the dynamics of illness transmission and potential measures for mitigating its effects are presented through the use of mathematical analysis and computational simulations. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 172−185

Lytic promoter activity during herpes simplex virus latency is dependent on genome location.

Herpes simplex virus 1 (HSV-1) is a significant pathogen that establishes lifelong latent infections with intermittent episodes of resumed disease. In mouse models of HSV infection, sporadic low-level lytic gene expression has been detected during latency in the absence of reactivation events that lead to production of new viruses. This viral activity during latency has been reported using a sensitive Cre-marking model for several lytic gene promoters placed in one location in the HSV-1 genome. Here, we extend these findings in the same model by examining first, the activity of an ectopic lytic gene promoter in several places in the genome and second, whether any promoters might be active in their natural context. We found that Cre expression was detected during latency from ectopic and native promoters, but only in locations near the ends of the unique long genome segment. This location is significant because it is in close proximity to the region from which latency-associated transcripts (LATs) are derived. These results show that native HSV-1 lytic gene promoters can produce protein products during latency, but that this activity is only detectable when they are located close to the LAT locus.IMPORTANCEHSV is a significant human pathogen and the best studied model of mammalian virus latency. Traditionally, the active (lytic) and inactive (latent) phases of infection were considered to be distinct, but the notion of latency being entirely quiescent is evolving due to the detection of some lytic gene expression during latency. Here, we add to this literature by finding that the activity can be found for native lytic gene promoters as well as for constructs placed ectopically in the HSV genome. However, this activity was only detectable when these promoters were located close by a region known to be transcriptionally active during latency. These data have implications for our understanding of HSV gene regulation during latency and the extent to which transcriptionally active regions are insulated from adjacent parts of the viral genome.

Radical-Scavenging Violet Phosphorus Nanosheets for Attenuating Hyperinflammation and Promoting Infected Wound Healing.

Antibacterial therapy targeting the regulation of macrophage polarization may be a useful approach for normalizing the immune environment and accelerating wound healing. Inspired by black phosphorus-based nanoplatforms, more stable yet less-explored violet phosphorus nanosheets (VPNSs) are expected to provide a superior solution for effectively combating bacterial infections. In this study, an average thickness of 5-7nm VPNSs arefabricated through the liquid-phase exfoliation method to serve as an immunoregulatory dressing for the treatment of infected wounds. VPNSs attenuated excessive reactive oxygen species (ROS) and reduced the accumulation of proinflammatory M1 macrophages, showing notable antioxidant and anti-inflammatory properties. Comprehensive RNA sequencing further elucidated the potential immunoregulatory mechanisms of VPNSs, including modulation of the inflammatory response and enzyme regulator activity. Additionally, the inherent photothermal properties of the VPNSs contributed significantly to their antibacterial efficacy. When combined with near-infrared laser irradiation, VPNSs showed remarkable effectiveness in reducing infection-related complications and expediting wound healing in infected skin wound models. The rapid promotion of wound healing through ROS clearance, the regulation of macrophage polarization, and hyperthermia generation underscores the potential of the violet-phosphorus-based nanoplatforms as clinically viable agents for treating infected wounds. This study suggests that VPNSs are promising candidates for clinical anti-infective and anti-inflammatory applications.

A human model of Buruli ulcer: Provisional protocol for a Mycobacterium ulcerans controlled human infection study.

Critical knowledge gaps have impeded progress towards reducing the global burden of disease due to Mycobacterium ulcerans, the cause of the neglected tropical disease Buruli ulcer (BU). Development of a controlled human infection model of BU has been proposed as an experimental platform to explore host-pathogen interactions and evaluate tools for prevention, diagnosis, and treatment. We have previously introduced the use case for a new human model and identified M. ulcerans JKD8049 as a suitable challenge strain. Here, we present a provisional protocol for an initial study, for transparent peer review during the earliest stages of protocol development. Following simultaneous scientific peer review and community/stakeholder consultation of this provisional protocol, we aim to present a refined protocol for institutional review board (IRB) evaluation.

Preclinical Positron Emission Tomography (PET) of Prosthetic Joint Infection Using a Nitro-Prodrug of 2-[18F]F-p-Aminobenzoic Acid ([18F]F-PABA).

Deep-seated bacterial infections are difficult to detect and diagnose due to the lack of specific clinical imaging modalities. Therefore, the bacteria-specific positron emission tomography radiotracer 2-[18F]fluoro-4-nitrobenzoic acid ([18F]FNB) was developed, which is reduced to 2-[18F]fluoro-4-aminobenzoic acid ([18F]F-PABA) by bacterial nitroreductases and has improved pharmacokinetics compared to the parent compound. PET imaging demonstrated that the uptake of 2-[18F]fluoro-4-nitrobenzoic acid in a clinically relevant Staphylococcus aureus prosthetic joint infection model was up to ∼4-fold higher in the infected joint compared to the contralateral joint. 2-[18F]Fluoro-4-nitrobenzoic acid was also able to distinguish infection from inflammation in a surgical inflammation model. Based on the mouse radiation dosimetry results, the calculated effective dose of 2-[18F]fluoro-4-nitrobenzoic acid was well below the whole-body radiation dose limit established by the Food and Drug Administration for humans. In addition, no treatment-related microscopic changes in organ histopathology were observed in a mouse acute toxicity study. Overall, these data suggest that 2-[18F]fluoro-4-nitrobenzoic acid is a specific and effective imaging agent for noninvasively diagnosing prosthetic joint infections.

Resource allocation for Hyphantria cunea invasive management:a novel simulation-based optimization model

In this study, we propose an integrated mixed-integer programming (MIP) model for allocating a limited budget to control a destructive invasive insect endangering the forest vegetation, Hyphantria cunea (H. cunea). Our model seeks to minimize the number of infected and dead trees within a preset planning period, factoring in various infestation scenarios, migration behaviors, resource limitations, intervention timing, and monitoring capabilities. Our modeling framework is novel in the sense that it depicts the transmission process of H. cunea as an infectious compartmental model. Our optimization model is also meaningful because it innovatively bridges the spread dynamics of H. cunea and the optimal resource allocation by using the time-varying number of infected trees that can be accepted in testing and surveillance. Our numerical test data and parameter settings have been collected from large-scale field surveys on H. cunea in Jiangsu Province over the past three years. The scenarios-based method offers significant computational advantages in searching for the best alternatives to real-world size problems in a rational time. Furthermore, our test results specify that the proposed model can not only aid in controlling H. cunea, but also can be adopted as a potential tool for managing other invasive species in the future.

Antibacterial activity and mechanism of colistin-loaded polymeric nanoparticles for combating multidrug-resistant Pseudomonas aeruginosa biofilms: A synergistic approach

Multidrug-resistant P. aeruginosa (MDR-P. aeruginosa), associated with elevated morbidity, mortality, and readmission rates, presents a formidable challenge to eradication due to its robust resistance to antimicrobial agents and biofilm formation. Herein, self-assembling nanoparticles (NO-PE/PLL NPs) comprised of NO donor-conjugated γ-polyglutamic acid (GSNO-PGA), epsilon-poly-l-lysine (PLL) and colistin were fabricated. The negatively charged NO-PE/PLL NPs exhibited effective penetration through airway mucus, reaching the infection site where GSNO-PGA released NO in response to glutathione within biofilm. PLL worked synergistically with colistin (fractional inhibitory concentration index: 0.281), reducing the minimum inhibitory concentration (MIC) of colistin from 2 to 0.5 μg/mL. Benefiting from this synergistic antibacterial action and NO-mediated biofilm disruption, NO-PE/PLL NPs achieved a 99.99 % eradication rate against MDR-P. aeruginosa biofilms. Additionally, NO-PE/PLL NPs efficiently inhibited endotoxins-stimulated inflammation response. In a chronic pulmonary infection model, NO-PE/PLL NPs displayed the highest eradication efficiency (99.78 %) to infected mice, while having no adverse effects on their major organs or pulmonary functions. These results highlight NO-PE/PLL NPs as a promising therapeutic strategy for treating recalcitrant infections caused by MDR-P. aeruginosa biofilms.

Broadly therapeutic antibody provides cross-serotype protection against enteroviruses via Fc effector functions and by mimicking SCARB2.

Enteroviruses contain multiple serotypes and can cause severe neurological complications. The intricate life cycle of enteroviruses involving dynamic virus-receptor interaction hampers the development of broad therapeutics and vaccines. Here, using function-based screening, we identify a broadly therapeutic antibody h1A6.2 that potently protects mice in lethal models of infection with both enterovirus A71 and coxsackievirus A16 through multiple mechanisms, including inhibition of the virion-SCARB2 interactions and monocyte/macrophage-dependent Fc effector functions. h1A6.2 mitigates inflammation and improves intramuscular mechanics, which are associated with diminished innate immune signalling and preserved tissue repair. Moreover, cryogenic electron microscopy structures delineate an adaptive binding of h1A6.2 to the flexible and dynamic nature of the VP2 EF loop with a binding angle mimicking the SCARB2 receptor. The coordinated binding mode results in efficient binding of h1A6.2 to all viral particle types and facilitates broad neutralization of enterovirus, therefore informing a promising target for the structure-guided design of pan-enterovirus vaccine.

Synergistic wall digestion and cuproptosis against fungal infections using lywallzyme-induced self-assembly of metal-phenolic nanoflowers

Fungi are very common infectious pathogens, which may cause invasive and potentially life-threatening infections. However, the efficacy of antifungal medications remains limited. Herein, a Cu2+-phenolic nanoflower is designed to combat fungal infections by combining cuproptosis and cell wall digestion. Firstly, protocatechuic acid (PA)-Cu2+ (PC) nanopetals are prepared by coordination interaction. Lywallzyme (Lyw) is then added to induce the self-assembly of PC to form Lyw loaded PC (PCW) nanoflowers. PCW nanoflowers can effectively adhere to fungal surface and Lyw can digest fungal cell walls to facilitate Cu2+ to penetrate into fungal interior, thereby exerting a synergistic fungicidal effect. PCW nanoflowers exhibit excellent fungicidal activity even in protein-rich and high-salt conditions, where dissociative Cu2+ completely loses fungicidal activity. Transcriptome sequencing analysis reveals that PCW can lead to fungal cuproptosis. The in vivo fungicidal effect of PCW nanoflowers is confirmed on a murine skin fungal infection model and a murine fungal keratitis model.

Development of bioluminescent Group B streptococcal strains for longitudinal infection studies.

Group B Streptococcus (GBS) remains the leading bacterial cause of invasive neonatal disease, resulting in substantial morbidity and mortality. New therapeutic approaches beyond antibacterial treatment to prevent neonatal disease outcomes are urgent. One significant limitation in studying GBS disease and progression is the lack of non-invasive technologies for longitudinal studies. Here, we develop and compare three bioluminescent GBS strains for in vivo pathogenic analysis. Bioluminescence is based on the luxABCDE operon on a replicative vector (luxGBS-CC17), and the red-shifted firefly luciferase on a replicative vector (fflucGBS-CC17) or integrated in the genome (glucGBS-CC17). We show that luxGBS-CC17 is suitable for in vitro analysis but does not produce a significant bioluminescent signal in infected pups. In contrast, the fflucGBS-CC17 results in a strong bioluminescent signal proportional to the organ colonisation level. However, the stability of the replicative vector depends on the route of infection, especially when pups acquire the bacteria from infected vaginal mucosa. Stable chromosomal integration of luciferase in glucGBS-CC17 leads to significant bioluminescence in both haematological and vertical infection models associated with high systemic colonisation. These strains will allow the preclinical evaluation of treatment efficacy against GBS invasive disease using whole-mouse bioluminescence imaging.

Quantitative performance of humanized serum and epithelial lining fluid exposures of tigecycline and levofloxacin against a challenge set of Klebsiella pneumoniae and Pseudomonas aeruginosa in a standardized neutropenic murine pneumonia model.

Lack of uniformity in infection models complicates preclinical development. The COMBINE protocol has standardized the murine neutropenic pneumonia model. Herein we provide benchmark efficacy data of humanized exposures of tigecycline and levofloxacin in plasma and epithelial lining fluid (ELF) against a collection of Klebsiella pneumoniae and Pseudomonas aeruginosa. Following the COMBINE protocol, plasma and ELF human-simulated regimens (HSRs) of tigecycline 100 mg followed by 50 mg q12h and levofloxacin 750 mg once daily were developed and confirmed in the murine neutropenic pneumonia model. Tigecycline HSRs were tested against seven K. pneumoniae isolates. Levofloxacin HSRs were assessed against 10 K. pneumoniae and 9 P. aeruginosa. The change in cfu/lung over 24 h for each treatment was calculated. Each isolate was tested in duplicate against both the plasma and ELF HSRs on separate experiment days. Tigecycline 1.8 and 3 mg/kg q12h achieved humanized exposures of serum and ELF, respectively. Levofloxacin 120 and 90 mg/kg q8h led to fAUC exposures in plasma and ELF similar to in humans. Both tigecycline regimens were ineffective across the MIC range. Levofloxacin regimens achieved multilog kill against susceptible isolates, and no appreciable cfu/lung reductions in isolates with an MIC of ≥32 mg/L. Differences in cfu/lung were evident between the levofloxacin plasma and ELF HSRs against isolates with MICs of 4 and 8 mg/L. Administering HSRs of tigecycline and levofloxacin based on both serum/plasma and ELF in the COMBINE pneumonia model resulted in cfu/lung values reasonably aligned with MIC. These data serve as translational benchmarks for future investigations with novel compounds.

Defending against backdoor attack on deep neural networks based on multi-scale inactivation

Deep neural networks (DNNs) have excellent performance in various applications, especially for image classification tasks. However, DNNs also face the threat of backdoor attacks. Backdoor attacks embed a hidden backdoor into a model, after which the infected model can achieve correct classification on benign images, while incorrectly classify the images with the backdoor triggers as the target label. To obtain a clean model from a backdoor dataset, we propose a Kalman filtering based multi-scale inactivation scheme, which can effectively remove poison data in a poison dataset and obtain a clean model. Every sample in the suspicious training dataset will be judged by multi-scale inactivation and obtain a series of judging results, then data fusion is conducted using kalman filtering to determine whether it is a poison sample. To further improve the performance, a trigger localization and target determination based scheme is proposed. Extensive experiments are conducted to demonstrate the superior effectiveness of the proposed method. The results show that the proposed methods can remove poison samples effectively, and achieve greater than 99% recall rate, and the attack success rate of the retrained clean model is smaller than 1%.