Biology subjects

Sutton, M.

Publications and source records attributed to Sutton, M..

5 recordsLinked to original sources

bioRxiv2024

SARS-CoV-2 infection enhancement by Amphotericin B: Implications for disease management

Severe coronavirus disease 2019 (COVID-19) patients who require hospitalisation are at high risk of invasive pulmonary mucormycosis. Amphotericin B (AmB), which is the first line therapy for invasive pulmonary mucormycosis, has been shown to promote or inhibit replication of a spectrum of viruses. In this study, we first predicted that AmB and Nystatin had strong interactions with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins using in silico screening, indicative of drugs with potential therapeutic activity against this virus. Subsequently, we investigated the impact of AmB, Nystatin, Natamycin, Fluconazole and Caspofungin on SARS-CoV-2 infection and replication in vitro. Results showed that AmB and Nystatin actually increased SARS-CoV-2 replication in Vero E6, Calu-3 and Huh7 cells. At optimal concentrations, AmB and Nystatin increase SARS-CoV-2 replication by up to 100- and 10-fold in Vero E6 and Calu-3 cells, respectively. The other antifungals tested had no impact on SARS-CoV-2 infection in vitro. Drug kinetic studies indicate that AmB enhances SARS-CoV-2 infection by promoting viral entry into cells. Additionally, knockdown of genes encoding for interferon-induced transmembrane (IFITM) proteins 1, 2, and 3 suggests AmB enhances SARS-CoV-2 cell entry by overcoming the antiviral effect of the IFITM3 protein. This study further elucidates the role of IFITM3 in viral entry and highlights the potential dangers of treating COVID-19 patients, with invasive pulmonary mucormycosis, using AmB. ImportanceAmB and Nystatin are common treatments for fungal infections but were predicted to strongly interact with SARS-CoV-2 proteins, indicating their potential modulation or inhibition against the virus. However, our tests revealed that these antifungals, in fact, enhance SARS-CoV-2 infection by facilitating viral entry into cells. The magnitude of enhancement could be up to 10- or 100-fold depending on cell lines used. These findings indicate that AmB and Nystatin have the potential to enhance disease when given to patients infected with SARS-CoV-2 and therefore should not be used for treatment of fungal infections in active COVID-19 cases.

microbiology↗

bioRxiv2024

Requirement for Fc effector function is overcome by binding potency for broadly reactive anti-alphavirus antibodies

Alphaviruses are emerging public health threats. Broadly reactive anti-alphavirus monoclonal antibodies (mAbs) have been shown to be protective in mouse models of infection. However, the mechanism of Fc-dependent or Fc-independent heterologous protection remains ill-defined in vivo. Here, we used two vaccine-elicited, broadly reactive, anti-alphavirus mAbs, SKT05 and SKT20, to establish correlates of mAb-mediated protection during Venezuelan equine encephalitis virus (VEEV) challenge. SKT20 required Fc effector functions to prevent lethality. In contrast, SKT05-mediated survival was independent of Fc effector functions, which is likely linked to early viral control through potent egress inhibition. However, control of virus replication and spread with SKT05 was Fc-dependent; these findings extended to additional in vivo models with alternative VEEV subtypes and chikungunya virus. During therapeutic delivery of SKT05, Fc effector functions were only required at 3 days post-infection. The necessity of Fc effector functions for SKT20 was related to mAb binding avidity rather than epitope and could be overcome by increasing the dose of SKT20 relative to the functional avidity of SKT05. Collectively, this study identified antibody avidity as a correlate for in vivo efficacy and associated Fc-dependent mechanisms that can be leveraged for therapeutic development of monoclonal antibodies against alphaviruses. One sentence summaryFunctional avidity of broadly reactive anti-alphavirus antibodies dictates requirement for Fc-mediated protection.

microbiology↗

bioRxiv2023

Variability in the phytoplankton response to upwelling across an iron limitation mosaic within the California Current System

Coastal upwelling currents such as the California Current System (CCS) comprise some of the most productive biological systems on the planet. Diatoms, a distinct taxon of phytoplankton, dominate these upwelling events in part due to their rapid response to nutrient entrainment. In this region, they may also be limited by the micronutrient iron (Fe), an important trace element primarily involved in photosynthesis and nitrogen assimilation. The mechanisms behind how diatoms physiologically acclimate to the different stages of the upwelling conveyor belt cycle with respect to Fe limitation remains largely uncharacterized. Here, we explore their physiological and metatranscriptomic response to the upwelling cycle with respect to the Fe limitation mosaic that exists in the CCS. Subsurface, natural plankton assemblages that would potentially seed surface blooms were examined over wide and narrow shelf regions. The initial biomass and physiological state of the phytoplankton community had a large impact on the overall response to simulated upwelling. Following on-deck incubation under varying Fe physiological states, our results suggest that diatoms quickly dominated the blooms by "frontloading" nitrogen assimilation genes prior to upwelling. However, diatoms subjected to induced Fe limitation exhibited reductions in carbon and nitrogen uptake and decreasing biomass accumulation. Simultaneously, they exhibited a distinct gene expression response which included increased expression of Fe-starvation induced proteins and decreased expression of nitrogen assimilation and photosynthesis genes. These findings may have significant implications for upwelling events in future oceans, where changes in ocean conditions are projected to amplify the gradient of Fe limitation in coastal upwelling regions.

plant biology↗

bioRxiv2023

Protective intravenous BCG vaccination induces enhanced immune signaling in the airways

Intradermal (ID) Bacillus Calmette-Guerin (BCG) is the most widely administered vaccine in the world. However, ID-BCG fails to achieve the level of protection needed in adults to alter the course of the tuberculosis epidemic. Recent studies in non-human primates have demonstrated high levels of protection against Mycobacterium tuberculosis (Mtb) following intravenous (IV) administration of BCG. However, the protective immune features that emerge following IV BCG vaccination remain incompletely defined. Here we used single-cell RNA-sequencing (scRNAseq) to transcriptionally profile 157,114 unstimulated and purified protein derivative (PPD)-stimulated bronchoalveolar lavage (BAL) cells from 29 rhesus macaques immunized with BCG across routes of administration and doses to uncover cell composition-, gene expression-, and biological network-level signatures associated with IV BCG-mediated protection. Our analyses revealed that high-dose IV BCG drove an influx of polyfunctional T cells and macrophages into the airways. These macrophages exhibited a basal activation phenotype even in the absence of PPD-stimulation, defined in part by IFN and TNF- signaling up to 6 months following BCG immunization. Furthermore, intercellular immune signaling pathways between key myeloid and T cell subsets were enhanced following PPD-stimulation in high-dose IV BCG-vaccinated macaques. High-dose IV BCG also engendered quantitatively and qualitatively stronger transcriptional responses to PPD-stimulation, with a robust Th1-Th17 transcriptional phenotype in T cells, and augmented transcriptional signatures of reactive oxygen species production, hypoxia, and IFN-{gamma} response within alveolar macrophages. Collectively, this work supports that IV BCG immunization creates a unique cellular ecosystem in the airways, which primes and enables local myeloid cells to effectively clear Mtb upon challenge.

immunology↗

bioRxiv2022

The First Inhibitor of Meso-Diaminopimelate Biosynthesis with Antibacterial Activity Against Multi-Drug Resistant Bacteria

Antibiotic resistance represents one of the biggest threats to global health. While several of our current antibiotics target the peptidoglycan within the bacterial cell wall, only a fraction of its components has been explored for antibiotic development. A component that remains under-exploited is meso-diaminopimelate (meso-DAP), a constituent of the cross-linking peptide in Gram-negative bacteria. In this study, we employed a high throughput chemical screen to identify the first inhibitor of meso-DAP biosynthesis with antibacterial activity. Indeed, the compound was shown to have minimum inhibitory concentration values of 8-16 g/mL against a panel of multi-drug resistant Acinetobacter baumannii strains, including those resistant to the last resort antibiotic carbapenem. Importantly, the compound targets the meso-DAP biosynthesis pathway specifically, with no off-target effects observed in human cell lines, and no resistance exhibited upon continuous treatment, under the conditions tested. Furthermore, we revealed for the first time that meso-DAP biosynthesis inhibition prevents biofilm formation and disrupts established biofilms in A. baumannii. Using a Galleria mellonella model, we showed that this compound improves survival rates against A. baumannii infection by up to 40% relative to the no treatment controls. Lastly, we determined that the inhibitor potentiates the activity of several antibiotic classes, including carbapenems. Thus, this study provides proof-of-concept that meso-DAP biosynthesis represents a promising target for the development of standalone antibacterial agents with a new mode of action as well as adjuvants to be used in combinatorial regimens to rejuvenate our current antibiotic arsenal to combat resistance. ImportanceResistance levels to available antibiotics continues to rise, with a growing number of Gram-negative bacterial infections, in particular A. baumannii infections, becoming life-threatening. Despite this, there have been no new classes of antibiotics against Gram-negative bacteria introduced to the market over the last 40 years. Hence, new targets and therapeutics are urgently required to combat these clinically important pathogens. One such target is meso-DAP, a critical component of the cross-linking peptides in the cell walls of Gram-negative bacteria. Here, we describe the first inhibitor of bacterial meso-DAP biosynthesis, with antibacterial activity against multi-drug resistant Gram-negative bacterial strains, including carbapenem-resistant A. baumannii. We also reveal that meso-DAP biosynthesis inhibition affects biofilm stability and potentiates the activity of several antibiotic classes. This study highlights the need to further explore meso-DAP biosynthesis and other unexploited targets in the search for antibiotics with new modes of action.

microbiology↗