Evolving challenges and strategies for fungal control in the food supply chain

Fungi that spoil foods or infect crops can have major socioeconomic impacts, posing threats to food security. The strategies needed to manage these fungi are evolving, given the growing incidence of fungicide resistance, tightening regulations of chemicals use and market trends imposing new food-preservation challenges. For example, alternative methods for crop protection such as RNA-based fungicides, biocontrol, or stimulation of natural plant defences may lessen concerns like environmental toxicity of chemical fungicides. There is renewed focus on natural product preservatives and fungicides, which can bypass regulations for ‘clean label’ food products. These require investment to find effective, safe activities within complex mixtures such as plant extracts. Alternatively, physical measures may be one key for fungal control, such as polymer materials which passively resist attachment and colonization by fungi. Reducing or replacing traditional chlorine treatments (e.g. of post-harvest produce) is desirable to limit formation of disinfection by-products. In addition, the current growth in lower sugar food products can alter metabolic routing of carbon utilization in spoilage yeasts, with implications for efficacy of food preservatives acting via metabolism. The use of preservative or fungicide combinations, while involving more than one chemical, can reduce total chemicals usage where these act synergistically. Such approaches might also help target different subpopulations within heteroresistant fungal populations. These approaches are discussed in the context of current challenges for food preservation, focussing on pre-harvest fungal control, fresh produce and stored food preservation. Several strategies show growing potential for mitigating or reversing the risks posed by fungi in the food supply chain

Discovery of (meth)acrylate polymers that resist colonization by fungi associated with pathogenesis and biodeterioration

© 2020 The Authors. Fungi have major, negative socioeconomic impacts, but control with bioactive agents is increasingly restricted, while resistance is growing. Here, we describe an alternative fungal control strategy via materials operating passively (i.e., no killing effect). We screened hundreds of (meth)acrylate polymers in high throughput, identifying several that reduce attachment of the human pathogen Candida albicans, the crop pathogen Botrytis cinerea, and other fungi. Specific polymer functional groups were associated with weak attachment. Low fungal colonization materials were not toxic, supporting their passive, anti-attachment utility. We developed a candidate monomer formulation for inkjet-based 3D printing. Printed voice prosthesis components showed up to 100% reduction in C. albicans biofilm versus commercial materials. Furthermore, spray-coated leaf surfaces resisted fungal infection, with no plant toxicity. This is the first high-throughput study of polymer chemistries resisting fungal attachment. These materials are ready for incorporation in products to counteract fungal deterioration of goods, food security, and health

The candidate antimalarial drug MMV665909 causes oxygen-dependent mRNA mistranslation and synergises with quinoline-derived antimalarials

To cope with growing resistance to current antimalarials, new drugs with novel modes of action are urgently needed. Molecules targeting protein synthesis appear to be promising candidates. We identified a compound (MMV665909) from the MMV Malaria Box of candidate antimalarials that could produce synergistic growth inhibition with the aminoglycoside antibiotic paromomycin, suggesting a possible action of the compound in mRNA mistranslation. This mechanism of action was substantiated with the yeast cell model using available reporters of mistranslation and other genetic tools. Mistranslation induced by MMV665909 was oxygen-dependent, suggesting a role for reactive oxygen species (ROS). Overexpression of Rli1 (a ROS-sensitive, conserved FeS protein essential in mRNA translation) rescued inhibition by MMV665909, consistent with the drug’s action on translation fidelity being mediated through Rli1. The MMV drug also synergised with major quinoline-derived antimalarials which can perturb amino acid availability or promote ROS stress: chloroquine, amodiaquine and primaquine. The data collectively suggest translation-fidelity as a novel target of antimalarial action and support MMV665909 as a promising drug candidate

Allelic Diversity of the Plasmodium falciparum Erythrocyte Membrane Protein 1 Entails Variant-Specific Red Cell Surface Epitopes

The clonally variant Plasmodium falciparum PfEMP1 adhesin is a virulence factor and a prime target of humoral immunity. It is encoded by a repertoire of functionally differentiated var genes, which display architectural diversity and allelic polymorphism. Their serological relationship is key to understanding the evolutionary constraints on this gene family and rational vaccine design. Here, we investigated the Palo Alto/VarO and IT4/R29 and 3D7/PF13_003 parasites lines. VarO and R29 form rosettes with uninfected erythrocytes, a phenotype associated with severe malaria. They express an allelic Cys2/group A NTS-DBL1α1 PfEMP1 domain implicated in rosetting, whose 3D7 ortholog is encoded by PF13_0003. Using these three recombinant NTS-DBL1α1 domains, we elicited antibodies in mice that were used to develop monovariant cultures by panning selection. The 3D7/PF13_0003 parasites formed rosettes, revealing a correlation between sequence identity and virulence phenotype. The antibodies cross-reacted with the allelic domains in ELISA but only minimally with the Cys4/group B/C PFL1955w NTS-DBL1α. By contrast, they were variant-specific in surface seroreactivity of the monovariant-infected red cells by FACS analysis and in rosette-disruption assays. Thus, while ELISA can differentiate serogroups, surface reactivity assays define the more restrictive serotypes. Irrespective of cumulated exposure to infection, antibodies acquired by humans living in a malaria-endemic area also displayed a variant-specific surface reactivity. Although seroprevalence exceeded 90% for each rosetting line, the kinetics of acquistion of surface-reactive antibodies differed in the younger age groups. These data indicate that humans acquire an antibody repertoire to non-overlapping serotypes within a serogroup, consistent with an antibody-driven diversification pressure at the population level. In addition, the data provide important information for vaccine design, as production of a vaccine targeting rosetting PfEMP1 adhesins will require engineering to induce variant-transcending responses or combining multiple serotypes to elicit a broad spectrum of immunity

Agents antimicrobiens ciblant le complexe III de la chaîne respiratoire mitochondriale (caractérisation de nouveaux inhibiteurs et étude du développement des résistances)

Des inhibiteurs du complexe bc1 de la chaîne respiratoire mitochondriale ont été développés comme agents antimicrobiens pour lutter contre des pathogènes de l Homme et de plantes. Ces drogues ciblent les poches catalytiques Qo et Qi formées par le cytochrome b. La comparaison de séquences de cette protéine montre que les sites Qo et Qi sont bien conservés entre les organismes mais qu il existe toutefois des variations qui pourraient expliquer leur différence de sensibilité aux drogues. A l aide du modèle levure S. cerevisiae, nous avons étudié les déterminants de la résistance/sensibilité naturelle à deux antipaludiques se liant au site Qo de Plasmodium: l atovaquone et RCQ06. Nous avons notamment montré que le résidu 275 joue un rôle clé dans ce phénomène. Une approche similaire est actuellement utilisée pour identifier les facteurs de la sensibilité différentielle à deux drogues ciblant le site Qi des oomycètes. Malheureusement, des cas de résistance acquise à ces antimicrobiens ont été rapportés et ont pour origine des mutations dans le cytochrome b. De ce fait, de nouvelles molécules sont requises pour court-circuiter ces résistances. Au cours de ma thèse, nous avons mis au point un test qui permet de cribler des molécules capables d inhiber la fonction respiratoire. Nous avons ainsi pu identifier un nouvel inhibiteur du complexe bc1 : D12. Nous avons ensuite déterminé le mode de liaison de cette molécule ainsi que celui d un composé capable d inhiber la prolifération de Plasmodium, HDQ, grâce à une collection de mutants des poches catalytiques. HDQ s est avéré être un inhibiteur du site Qi. Il pourrait être utilisé avec un inhibiteur du site Qo afin de limiter l apparition de mutations de résistance. D12 est un inhibiteur du site Qo qui est capable notamment de court-circuiter la mutation de résistance à des fongicides du site Qo G143A. Cette dernière a été trouvée chez de nombreux phytopathogènes, mais n est cependant pas apparue chez des champignons possédant un intron immédiatement après le codon codant pour la glycine 143. En utilisant la levure, nous avons montré que la mutation empêche l épissage de l intron en altérant la structure exon/intron. Nous avons également identifié des mécanismes de by-pass qui permettent de restaurer la fonction respiratoire du mutant et qui pourraient apparaître chez les pathogènes. Les mutants créés au cours de ma thèse pourront aider à identifier, concevoir et caractériser de nouveaux antimicrobiens et à étudier l apparition de mutations de résistance.Inhibitors of the mitochondrial respiratory chain bc1 complex are currently used against human and plant pathogens. These drugs bind to Qo and Qi pockets of the mitochondrially-encoded cytochrome b. Comparison of the cytochrome b sequences shows that the Qo and Qi sites are well conserved between organisms. However, there are variations that could explain the differential sensitivity to respiratory inhibitors. In order to investigate the determinants of resistance / sensitivity to the antimalarial compounds, atovaquone and RCQO6, we used S.cerevisiae as a model. We showed that residue 275 plays a central role in the sensitivity to these drugs. We are now using a similar approach to identify the determinants of sensitivity towards two drugs targeting the oomycete Qi site. Unfortunately, cases of acquired resistance to these antimicrobial agents have been reported. They are caused by mutations in the cytochrome b. Thus, new molecules are required to bypass resistance. During my PhD, we developed a test to screen chemical libraries and identify inhibitors of the respiratory function. We identified a novel inhibitor of bc1 complex: D12. We determined the binding mode of D12 as well as of HDQ, a compound capable of inhibiting the proliferation of Plasmodium. To do this, we used a collection of mutants with alterations of the catalytic pockets. We showed that HDQ targets the Qi site. This finding suggests that HDQ could be used with an inhibitor of the Qo site to limit the emergence of resistance mutations. D12 is an inhibitor of Qo site and fully active against the enzyme harbouring the fungicide resistance mutation G143A. This mutation has been reported in many plant pathogenic fungi but has not evolved in fungi that harbour an intron immediately after the codon for G143. Using yeast, we showed that the mutation hinders the splicing of this intron by altering the exon / intron structure needed for efficient intron excision. We also identified by-pass mechanisms that restore respiratory function of the G143A mutant. These mechanisms identified in yeast could potentially arise in pathogenic fungi. Mutants created during my PhD will help to identify, design and characterize new drugs and to study the emergence of resistance mutations.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Safety of adjuvant atezolizumab after pneumonectomy/bilobectomy in stage II-IIIA non-small cell lung cancer in the randomized phase III IMpower010 trial.

OBJECTIVE: Adjuvant atezolizumab is a standard of care after chemotherapy in completely resected stage II-IIIA programmed death ligand-1 tumor cell 1% or greater non-small cell lung cancer based on results from the phase III IMpower010 study. We explored the safety and tolerability of adjuvant atezolizumab by surgery type in IMpower010. METHODS: Patients had completely resected stage IB-IIIA non-small cell lung cancer (Union Internationale Contre le Cancer/American Joint Committee on Cancer, 7th Ed), received up to four 21-day cycles of cisplatin-based chemotherapy, and were randomized 1:1 to receive atezolizumab 1200 mg every 3 weeks (≤16 cycles or 1 year) or best supportive care. Adverse events and clinical characteristics were investigated by surgery type (pneumonectomy/bilobectomy or lobectomy/sleeve lobectomy) in the randomized stage II-IIIA population who received 1 or more atezolizumab dose or with 1 or more postbaseline assessment (safety evaluable) for best supportive care. RESULTS: Overall, 871 patients comprised the safety-evaluable randomized stage II-IIIA population. In the atezolizumab arm, 23% (100/433) received pneumonectomy/bilobectomy and 77% (332/433) received lobectomy/sleeve lobectomy. Atezolizumab discontinuation occurred in 32% (n = 32) and 35% (n = 115) of the pneumonectomy/bilobectomy and lobectomy/sleeve lobectomy groups, respectively. Grade 3/4 adverse events were reported in 21% (n = 21) and 23% (n = 76) of patients in the atezolizumab arms in the pneumonectomy/bilobectomy and lobectomy/sleeve lobectomy groups, respectively. In the atezolizumab arms of the surgery groups, 13% (n = 13) and 17% (n = 55) had an adverse event leading to hospitalization. Atezolizumab-related adverse events leading to hospitalization occurred in 5% (n = 5) and 7% (n = 23) of the surgery groups. CONCLUSIONS: These exploratory findings support use of adjuvant atezolizumab after platinum-based chemotherapy in patients with completely resected stage II-IIIA programmed death ligand-1 tumor cell 1% or more non-small cell lung cancer, regardless of surgery type

On Cartan matrices with two parameters (Cohomology theory of finite groups and related topics)

A major cause of the paucity of new starting points for drug discovery is the lack of interaction between academia and industry. Much of the global resource in biology is present in universities, whereas the focus of medicinal chemistry is still largely within industry. Open source drug discovery, with sharing of information, is clearly a first step towards overcoming this gap. But the interface could especially be bridged through a scale-up of open sharing of physical compounds, which would accelerate the finding of new starting points for drug discovery. The Medicines for Malaria Venture Malaria Box is a collection of over 400 compounds representing families of structures identified in phenotypic screens of pharmaceutical and academic libraries against the Plasmodium falciparum malaria parasite. The set has now been distributed to almost 200 research groups globally in the last two years, with the only stipulation that information from the screens is deposited in the public domain. This paper reports for the first time on 236 screens that have been carried out against the Malaria Box and compares these results with 55 assays that were previously published, in a format that allows a meta-analysis of the combined dataset. The combined biochemical and cellular assays presented here suggest mechanisms of action for 135 (34%) of the compounds active in killing multiple life-cycle stages of the malaria parasite, including asexual blood, liver, gametocyte, gametes and insect ookinete stages. In addition, many compounds demonstrated activity against other pathogens, showing hits in assays with 16 protozoa, 7 helminths, 9 bacterial and mycobacterial species, the dengue fever mosquito vector, and the NCI60 human cancer cell line panel of 60 human tumor cell lines. Toxicological, pharmacokinetic and metabolic properties were collected on all the compounds, assisting in the selection of the most promising candidates for murine proof-of-concept experiments and medicinal chemistry programs. The data for all of these assays are presented and analyzed to show how outstanding leads for many indications can be selected. These results reveal the immense potential for translating the dispersed expertise in biological assays involving human pathogens into drug discovery starting points, by providing open access to new families of molecules, and emphasize how a small additional investment made to help acquire and distribute compounds, and sharing the data, can catalyze drug discovery for dozens of different indications. Another lesson is that when multiple screens from different groups are run on the same library, results can be integrated quickly to select the most valuable starting points for subsequent medicinal chemistry efforts

Metabolomic and chemogenomic profiling.

<p>(A) Metabolic profiling: Heat map showing metabolic fingerprints of 80 Malaria Box compounds and atovaquone control. Parasite extracts were analyzed by LC-MS, and changes in metabolite pools were calculated for drug-treated parasites as compared to untreated controls. Hierarchical clustering was performed on ²log-fold changes in metabolites (data in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005763#ppat.1005763.s003" target="_blank">S2 Table</a>), scaled from -3 to +3. Six of seven compounds (indicated in red) reported to target <i>Pf</i>ATP4 [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005763#ppat.1005763.ref025" target="_blank">25</a>] showed a distinct metabolic response characterized by the accumulation of dNTPs and a decrease in hemoglobin-derived peptides. A large cluster of compounds (indicated in blue) clustered with the atovaquone control (indicated in orange), and exhibit an atovaquone-like signature characterized by dysregulation of pyrimidine biosynthesis, and showed a distinct metabolic response characterized by the accumulation of dNTPs and a decrease in hemoglobin-derived peptides. (B) Chemogenomic profiling: A collection of 35 <i>P</i>. <i>falciparum</i> single insertion <i>piggyBac</i> mutants were profiled with 53 MMV compounds and 3 artemisinin (ART) compounds [Artesunate (AS), Artelinic acid (AL) and Artemether (AM)] for changes in IC₅₀ relative to the wild-type parent NF54 (data in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005763#ppat.1005763.s004" target="_blank">S3 Table</a>, genes queried in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005763#ppat.1005763.s005" target="_blank">S4 Table</a>). Clone PB58 carried a <i>piggyBac</i> insertion in the promoter region of the K13 gene and has an increased sensitivity to ART compounds as do PB54 and PB55 [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005763#ppat.1005763.ref033" target="_blank">33</a>]. Drug-drug relationships based on similarities in IC₅₀ deviations of compounds generated with <i>piggyBac</i> mutants created chemogenomic profiles used to define drug-drug relationships. The significance of similarity in MoA between Malaria Box compounds and ART was evaluated by Pearson’s correlation calculations from pairwise comparisons. The X axis shows the chemogenomic profile correlation between a Malaria Box compound and AS, the Y axis with AM; the color gradient indicates the average correlation with all ART derivatives tested. Five Malaria Box compounds (MMV006087, MMV006427, MMV020492, MMV665876, MMV396797) were identified as having similar drug-drug chemogenomic profiles to the ART sensitivity cluster.</p