Hidden Selection of Bacterial Resistance to Fluoroquinolones In Vivo: The Case of Legionella pneumophila and Humans

AbstractPlasmodium falciparum malaria contributes to a significant global disease burden. Circumsporozoite protein (CSP), the most abundant sporozoite stage antigen, is a prime vaccine candidate. Inhibitory monoclonal antibodies (mAbs) against CSP map to either a short junctional sequence or the central (NPNA)n repeat region. We compared in vitro and in vivo activities of six CSP-specific mAbs derived from human recipients of a recombinant CSP vaccine RTS,S/AS01 (mAbs 317 and 311); an irradiated whole sporozoite vaccine PfSPZ (mAbs CIS43 and MGG4); or individuals exposed to malaria (mAbs 580 and 663). RTS,S mAb 317 that specifically binds the (NPNA)n epitope, had the highest affinity and it elicited the best sterile protection in mice. The most potent inhibitor of sporozoite invasion in vitro was mAb CIS43 which shows dual-specific binding to the junctional sequence and (NPNA)n. In vivo mouse protection was associated with the mAb reactivity to the NANPx6 peptide, the in vitro inhibition of sporozoite invasion activity, and kinetic parameters measured using intact mAbs or their Fab fragments. Buried surface area between mAb and its target epitope was also associated with in vivo protection. Association and disconnects between in vitro and in vivo readouts has important implications for the design and down-selection of the next generation of CSP based interventions.

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Antibacterial Mechanisms and Efficacy of Sarecycline in Animal Models of Infection and Inflammation

Antibiotics ◽

10.3390/antibiotics10040439 ◽

2021 ◽

Vol 10 (4) ◽

pp. 439

Author(s):

Christopher G. Bunick ◽

Jonette Keri ◽

S. Ken Tanaka ◽

Nika Furey ◽

Giovanni Damiani ◽

...

Keyword(s):

Broad Spectrum ◽

Bacterial Resistance ◽

Antibiotic Use ◽

In Vivo Studies ◽

Infection Model ◽

Severe Acne ◽

Rat Paw Edema ◽

Infection And Inflammation

Prolonged broad-spectrum antibiotic use is more likely to induce bacterial resistance and dysbiosis of skin and gut microflora. First and second-generation tetracycline-class antibiotics have similar broad-spectrum antibacterial activity. Targeted tetracycline-class antibiotics are needed to limit antimicrobial resistance and improve patient outcomes. Sarecycline is a narrow-spectrum, third-generation tetracycline-class antibiotic Food and Drug Administration (FDA)-approved for treating moderate-to-severe acne. In vitro studies demonstrated activity against clinically relevant Gram-positive bacteria but reduced activity against Gram-negative bacteria. Recent studies have provided insight into how the structure of sarecycline, with a unique C7 moiety, interacts with bacterial ribosomes to block translation and prevent antibiotic resistance. Sarecycline reduces Staphylococcus aureus DNA and protein synthesis with limited effects on RNA, lipid, and bacterial wall synthesis. In agreement with in vitro data, sarecycline demonstrated narrower-spectrum in vivo activity in murine models of infection, exhibiting activity against S. aureus, but reduced efficacy against Escherichia coli compared to doxycycline and minocycline. In a murine neutropenic thigh wound infection model, sarecycline was as effective as doxycycline against S. aureus. The anti-inflammatory activity of sarecycline was comparable to doxycycline and minocycline in a rat paw edema model. Here, we review the antibacterial mechanisms of sarecycline and report results of in vivo studies of infection and inflammation.

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Cortical neurons exhibit diverse myelination patterns that scale between mouse brain regions and regenerate after demyelination

Nature Communications ◽

10.1038/s41467-021-25035-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Cody L. Call ◽

Dwight E. Bergles

Keyword(s):

Cortical Neurons ◽

Regional Differences ◽

Brain Regions ◽

Axon Diameter ◽

Neuronal Identity ◽

Cortical Areas ◽

Myelin Sheaths ◽

Parvalbumin Interneurons ◽

Selection Of

ABSTRACTAxons in the cerebral cortex show a broad range of myelin coverage. Oligodendrocytes establish this pattern by selecting a cohort of axons for myelination; however, the distribution of myelin on distinct neurons and extent of internode replacement after demyelination remain to be defined. Here we show that myelination patterns of seven distinct neuron subtypes in somatosensory cortex are influenced by both axon diameter and neuronal identity. Preference for myelination of parvalbumin interneurons was preserved between cortical areas with varying myelin density, suggesting that regional differences in myelin abundance arises through local control of oligodendrogenesis. By imaging loss and regeneration of myelin sheaths in vivo we show that myelin distribution on individual axons was altered but overall myelin content on distinct neuron subtypes was restored. Our findings suggest that local changes in myelination are tolerated, allowing regenerated oligodendrocytes to restore myelin content on distinct neurons through opportunistic selection of axons.

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Development of a Fluorescent Tool for Studying Legionella bozemanae Intracellular Infection

Microorganisms ◽

10.3390/microorganisms9020379 ◽

2021 ◽

Vol 9 (2) ◽

pp. 379

Author(s):

Breanne M. Head ◽

Christopher I. Graham ◽

Teassa MacMartin ◽

Yoav Keynan ◽

Ann Karen C. Brassinga

Keyword(s):

Growth Kinetics ◽

Legionella Pneumophila ◽

Fluorescent Protein ◽

Disease Incidence ◽

Acanthamoeba Castellanii ◽

Infection Model ◽

Intracellular Infection ◽

Green Fluorescent

Legionnaires’ disease incidence is on the rise, with the majority of cases attributed to the intracellular pathogen, Legionella pneumophila. Nominally a parasite of protozoa, L. pneumophila can also infect alveolar macrophages when bacteria-laden aerosols enter the lungs of immunocompromised individuals. L. pneumophila pathogenesis has been well characterized; however, little is known about the >25 different Legionella spp. that can cause disease in humans. Here, we report for the first time a study demonstrating the intracellular infection of an L. bozemanae clinical isolate using approaches previously established for L. pneumophila investigations. Specifically, we report on the modification and use of a green fluorescent protein (GFP)-expressing plasmid as a tool to monitor the L. bozemanae presence in the Acanthamoeba castellanii protozoan infection model. As comparative controls, L. pneumophila strains were also transformed with the GFP-expressing plasmid. In vitro and in vivo growth kinetics of the Legionella parental and GFP-expressing strains were conducted followed by confocal microscopy. Results suggest that the metabolic burden imposed by GFP expression did not impact cell viability, as growth kinetics were similar between the GFP-expressing Legionella spp. and their parental strains. This study demonstrates that the use of a GFP-expressing plasmid can serve as a viable approach for investigating Legionella non-pneumophila spp. in real time.

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The identification of novel immunogenic antigens as potential Shigella vaccine components

Genome Medicine ◽

10.1186/s13073-020-00824-4 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Ruklanthi de Alwis ◽

Li Liang ◽

Omid Taghavian ◽

Emma Werner ◽

Hao Chung The ◽

...

Keyword(s):

Core Genome ◽

Genomic Analysis ◽

Carrier Proteins ◽

Vaccine Candidates ◽

Vaccine Antigens ◽

Bactericidal Antibody ◽

In Vivo Testing ◽

Species Specific ◽

Selection Of

Abstract Background Shigella is a major diarrheal pathogen for which there is presently no vaccine. Whole genome sequencing provides the ability to predict and derive novel antigens for use as vaccines. Here, we aimed to identify novel immunogenic Shigella antigens that could serve as Shigella vaccine candidates, either alone, or when conjugated to Shigella O-antigen. Methods Using a reverse vaccinology approach, where genomic analysis informed the Shigella immunome via an antigen microarray, we aimed to identify novel immunogenic Shigella antigens. A core genome analysis of Shigella species, pathogenic and non-pathogenic Escherichia coli, led to the selection of 234 predicted immunogenic Shigella antigens. These antigens were expressed and probed with acute and convalescent serum from microbiologically confirmed Shigella infections. Results Several Shigella antigens displayed IgG and IgA seroconversion, with no difference in sero-reactivity across by sex or age. IgG sero-reactivity to key Shigella antigens was observed at birth, indicating transplacental antibody transfer. Six antigens (FepA, EmrK, FhuA, MdtA, NlpB, and CjrA) were identified in in vivo testing as capable of producing binding IgG and complement-mediated bactericidal antibody. Conclusions These findings provide six novel immunogenic Shigella proteins that could serve as candidate vaccine antigens, species-specific carrier proteins, or targeted adjuvants.

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Preclinical Testing of Radiopharmaceuticals for the Detection and Characterization of Osteomyelitis: Experiences from a Porcine Model

Molecules ◽

10.3390/molecules26144221 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4221

Author(s):

Aage Kristian Olsen Alstrup ◽

Svend Borup Jensen ◽

Ole Lerberg Nielsen ◽

Lars Jødal ◽

Pia Afzelius

Keyword(s):

Animal Model ◽

Animal Models ◽

Porcine Model ◽

Animal Experiments ◽

Radioactive Tracers ◽

The Individual ◽

Selection Of

The development of new and better radioactive tracers capable of detecting and characterizing osteomyelitis is an ongoing process, mainly because available tracers lack selectivity towards osteomyelitis. An integrated part of developing new tracers is the performance of in vivo tests using appropriate animal models. The available animal models for osteomyelitis are also far from ideal. Therefore, developing improved animal osteomyelitis models is as important as developing new radioactive tracers. We recently published a review on radioactive tracers. In this review, we only present and discuss osteomyelitis models. Three ethical aspects (3R) are essential when exposing experimental animals to infections. Thus, we should perform experiments in vitro rather than in vivo (Replacement), use as few animals as possible (Reduction), and impose as little pain on the animal as possible (Refinement). The gain for humans should by far exceed the disadvantages for the individual experimental animal. To this end, the translational value of animal experiments is crucial. We therefore need a robust and well-characterized animal model to evaluate new osteomyelitis tracers to be sure that unpredicted variation in the animal model does not lead to a misinterpretation of the tracer behavior. In this review, we focus on how the development of radioactive tracers relies heavily on the selection of a reliable animal model, and we base the discussions on our own experience with a porcine model.

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Selection of Fluorescent, Bioluminescent, and Radioactive Tracers to Accurately Reflect Extracellular Vesicle Biodistribution in Vivo

ACS Nano ◽

10.1021/acsnano.0c09873 ◽

2021 ◽

Vol 15 (2) ◽

pp. 3212-3227

Author(s):

Elisa Lázaro-Ibáñez ◽

Farid N. Faruqu ◽

Amer F. Saleh ◽

Andreia M. Silva ◽

Julie Tzu-Wen Wang ◽

...

Keyword(s):

Extracellular Vesicle ◽

Radioactive Tracers ◽

Selection Of

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Clinical Application and Efficacy of Silver Drug in Ophthalmology: A Literature Review and New Formulation of EYE Drops with Drug Silver (I) Complex of Metronidazole with Improved Dosage Form

Biomedicines ◽

10.3390/biomedicines9020210 ◽

2021 ◽

Vol 9 (2) ◽

pp. 210

Author(s):

Arleta Waszczykowska ◽

Dominik Żyro ◽

Justyn Ochocki ◽

Piotr Jurowski

Keyword(s):

Dosage Form ◽

Complex Analysis ◽

Bacterial Resistance ◽

Eye Drops ◽

Ophthalmic Diseases ◽

The Stability ◽

New Formulation ◽

Additional Therapy ◽

Antibacterial Potential

The use of silver preparations in medicine is becoming increasingly popular. The basic aim of this evaluation was to review the literature on the clinical (in vivo) and antibacterial potential of silver preparations in ophthalmic diseases. The second goal was to summarize the results of experimental research on the use of silver preparations in ophthalmology. The third objective was to present a method for stabilizing eye drops containing silver (I) complex. Analysis of the pH stability of the silver (I) complex with metronidazole in the prepared dosage form (eye drops) was carried out. Most silver preparations are clinically used for topical application. Few experimental results indicate the usefulness of intraocular or systemic administration of silver (I) preparations as an alternative or additional therapy in infectious and angiogenic eye diseases. The development of a new formulation increases the stability of the dosage form. New forms of silver (I) products will certainly find application in the treatment of many ophthalmic diseases. One of the most important features of the silver (I) complex is its capacity to break down bacterial resistance. The new eye drops formula can significantly improve comfort of use. Due to their chemical nature, silver (I) compounds are difficult to stabilize, especially in the finished dosage form.

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