Biology subjects

Toth, I.

Publications and source records attributed to Toth, I..

6 recordsLinked to original sources

bioRxiv2024

A modular self-assembling and self-adjuvanting multiepitope peptide nanoparticle vaccine platform to improve the efficacy and immunogenicity of BCG

After more than a century since its initial development, Bacille Calmette-Guerin (BCG) remains the only licensed vaccine against tuberculosis (TB). Subunit boosters are considered a viable strategy to enhance BCG efficacy, which often wanes in adolescence. While many studies on booster subunit vaccines have concentrated on recombinant proteins, here we developed a novel modular peptide-based subunit vaccine platform that is flexible, cold-chain independent and customizable to diverse circumstances and populations. Each individual peptide building block consists of a linear arrangement comprising a 15-leucine self-assembly inducer moiety, a Mycobacterium tuberculosis (Mtb) target epitope and an HLA-E binding moiety, with each moiety separated by a triple lysine spacer. The building blocks, in any combination, were able to form a multiepitope nanoparticle. Six Mtb epitopes were selected to produce the self-assembling and self-adjuvanting peptide-based TB nano-vaccine candidate PNx6. In vivo vaccination-challenge experiments demonstrated that subcutaneous boost of parenteral BCG immunization with PNx6 significantly enhanced its immunogenicity and improved its protective efficacy in a murine model of TB by more than 5-fold. Our study present evidence that purely amphiphilic peptides self-assemble into self-adjuvanting nanoparticles with appropriate size and morphology for TB vaccination with great potential for a multitude of other diseases.

microbiology↗

bioRxiv2024

A One Health approach metagenomic study on the antimicrobial resistance traits of canine saliva

According to the One Health concept, physical proximity among pets and their owners facilitates the spread of various bacteria. Interspecies bacterial transfer media include canine saliva that can be transmitted by licking and biting. Antimicrobial resistance genes (ARGs) are the natural constituents of the bacterial genome. However, human activity can increase the prominence of ARGs. To assess factors that may affect the resistome of the canine oral cavity, the shotgun metagenomic sequencing dataset of 1830 canine saliva samples was bioinformatically analyzed and supplemented with survey results of the physical and behavioral traits of the dogs. Bacteriome and resistome associated with the canine saliva samples were described throughout the analysis. Moreover, the subset of higher public health ARGs and ESKAPE pathogen-related (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) higher public health ARGs were also collected. Further on, the set and subsets of ARGs were studied considering the surveyed traits of the sampled dogs. Overall, 318 ARG types reached sufficiently high detection rates. These ARGs can affect 31 antibiotic drug classes by various resistance mechanisms. ARGs against tetracyclines and cephalosporins appeared in the highest number of samples. However, surprisingly, another CIA group, peptides were represented by ARGs in the third-highest number of samples. Considering further ARG appearance rates in the samples, Critically Important Antimicrobials (CIAs, WHO), such as aminoglycosides, fluoroquinolones, or macrolides, were among the most frequently affected drug classes by higher public health risk ARGs and ESKAPE pathogen related higher public health risk ARGs. Bacteria in the saliva of white and diluted (merle, gray) color dogs and dogs characterized with decreased activity and decreased aggression more often harbored ARGs. Reduced playfulness could have been specifically associated with higher public health risk ARG presence. Even though the oral microbiome of the owners is unknown, One Health and public health implications of the close human-pet bonds and factors potentially underlying the rise in salivary ARG numbers should be considered, mostly in the light of the presence of ARGs affecting critically important drugs for human medicine.

genomics↗

bioRxiv2023

Balancing the scales: Impact of irrigation and pathogen burden on potato blackleg disease and soil microbial communities

Understanding the interaction between environmental conditions, crop yields, and soil health is crucial for sustainable agriculture in a changing climate. Management practices to limit disease are a balancing act. For example, in potato production, dry conditions favour common scab (Streptomyces spp.) and wet conditions favour blackleg disease (Pectobacterium spp.). The exact mechanisms involved and how these link to changes in the soil microbiome is unclear. Our objectives were to test how irrigation management and bacterial pathogen load in potato seed stocks impact: i) crop yields; ii) disease development (blackleg/common scab); and iii) soil microbial community dynamics. We used stocks of seed potatoes with varying Pectobacterium levels (Jelly [high load], Jelly [low load], and Estima [Zero - no Pectobacterium]). Stocks were grown under four irrigation regimes that differed in the timing and level of watering. The soil microbial communities were profiled using amplicon sequencing at 50% plant emergence and harvest and advanced bioinformatic analyses were used to correlate microbes to treatments and disease symptoms. Irrigation increased blackleg symptoms in the plots planted with stocks with low and high levels of Pectobacterium (22-34%) but not in the zero stock (2-6%). Not irrigating increased common scab symptoms (2-5%) and reduced crop yields. Irrigation did not impact the composition of the soil microbiome, but planting stock with a high Pectobacterium burden resulted in an increased abundance of Planctomycetota, Anaerolinea, and Acidobacteria species within the microbiome. Ensemble quotient analysis highlighted Anaerolinea as highly associated with blackleg symptoms in the field. We conclude that Pectobacterium pathogen load within seed stocks could have more substantial effects on soil communities than irrigation regimes.

microbiology↗

bioRxiv2022

Canine saliva is a source of interspecies antimicrobial resistance gene transfer

While the One Health issues of intensive animal farming are commonly discussed, keeping companion animals is less associated with the interspecies headway of antimicrobial resistance. With the constant advance of veterinary standards, antibiotics are regularly applied in companion animal medicine. Due to the close coexsistance of dogs and humans, dog bites and other casual encounters with dog saliva (e.g. licking the owner) are common. According to our metagenome studies based on 26 new generation sequencing canine saliva datasets from 2020 and 2021 reposited in NCBI SRA by The 10,000 Dog Genome Consortium and the Broad Institute within Darwins Ark project, canine saliva is rich in bacteria with predictably transferable antimicrobial resistance genes (ARGs). In the genom of potentially pathogenic Bacteroides, Capnocytophaga, Corynebacterium, Fusobacterium, Pasteurella, Porphyromonas, Staphylococcus and Streptococcus species, that are some of the most relevant bacteria in dog bite infections, ARGs against aminoglycosides, carbapenems, cephalosporins, glycylcyclines, lincosamides, macrolides, oxazolidinone, penams, phenicols, pleuromutilins, streptogramins, sulfonamides and tetracyclines could be identfied. Several ARGs, including ones against amoxicillin-clavulanate, the most commonly applied antibiotic by dog bites, was predicted to be potentially transferable based on their association with mobile genetic elements (e.g. plasmids, phages, integrated mobile genetic elements). According to our findings canine saliva may be a source of transfer of ARG-rich bacteria, that can either colonize the human body or transport ARGs to the host bacteriota and thus can be considered as a risk in the spread of antimicrobial resistance.

genomics↗

bioRxiv2022

Uncertainties of cell number estimation in cyanobacterial colonies and the potential use of sphere packing

Cyanobacteria are notorious bloom formers causing various water quality concerns, such as toxin production, extreme diurnal variation of oxygen, or pH, etc., therefore, their monitoring is essential to protect the ecological status of aquatic systems. Cyanobacterial cell counts and biovolumes are currently being used in water management and water quality alert systems. In this study, we investigated the accuracy of colonial biovolume and cell count estimation approaches used in the everyday practice. Using real like 3-dimensional images of cyanobacterial colonies, we demonstrated that their shape cannot be approximated by ellipsoids. We also showed that despite the significant relationship between overall colony volume and cell biovolumes because of the considerable scatter of cell count data the regressions give biased estimates for cyanobacterial cell counts. We proposed a novel approach to estimate cell counts in colonies that was based on the random close sphere packing method. This method provided good results only in those cases when overall colony volumes could be accurately measured. The visual investigation of colonies done by skilled experts has given precise but lower estimates for cell counts. Estimation results of several experts were surprisingly good which suggest that this capability can be improved, and estimation bias can be reduced to the level acceptable for water quality estimations. HighlightsCyanobacterial colony - cell biovolume relationships provide biased estimates for cellbiovolumes. Sphere packing approach provides good cellcount estimates if colony volumes are accurately measured. Considering cyanobacterial colonies as ellipsoids gives inaccurate volume estimates. Skilled experts slightly underestimate the cellcounts but dispersion of their estimates is low.

ecology↗

bioRxiv2021

The role of L-arabinose metabolism for Escherichia coli O157:H7 in edible plants

Arabinose is a major plant aldopentose in the form of arabinans complexed in cell wall polysaccharides or glycoproteins (AGP), but comparatively rare as a monosaccharide. L-arabinose is an important bacterial metabolite, accessed by pectolytic microorganisms such as Pectobacterium atrosepticum via pectin and hemicellulose degrading enzymes. However, not all plant-associated microbes encode cell wall degrading enzymes, yet can metabolise L-arabinose, raising questions about their use of and access to the glycan in plants. Therefore, we examined L-arabinose metabolism in the food-borne pathogen Escherichia coli O157:H7 (isolate Sakai) during its colonisation of plants. L-arabinose metabolism (araBA) and transport (araF) genes were activated at 18 {degrees}C in vitro by L-arabinose and expressed over prolonged periods in planta. Although deletion of araBAD did not impact the colonisation ability of E. coli O157:H7 (Sakai) on plants, araA was induced on exposure to spinach cell wall polysaccharides. Furthermore, debranched and arabinan oligosaccharides induced ara metabolism gene expression in vitro, and stimulated modest proliferation, while immobilised pectin did not. Thus, E. coli O157:H7 (Sakai) can utilise pectin/AGP- derived L-arabinose as a metabolite, but differs fundamentally in ara gene organisation, transport and regulation from the related pectinolytic species P. atrosepticum, reflective of distinct plant- associated lifestyles.

microbiology↗