Project description:Pseudomonas syringae pv. phaseolicola (Pph) is a significant bacterial pathogen of agricultural crops, and phage Φ6 and other members of the dsRNA virus family Cystoviridae undergo lytic (virulent) infection of Pph, using the type IV pilus as the initial site of cellular attachment. Despite the popularity of Pph/phage Φ6 as a model system in evolutionary biology, Pph resistance to phage Φ6 remains poorly characterized. To investigate differences between phage Φ6 resistant Pseudomonas syringae pathovar phaseolicola strains, we performed expression analysis of super and non piliated strains of Pseudomonas syringae to determine the genetic cause of resistance to viral infection.
Project description:Bacteriophages are increasingly recognised as key players in modulating plant-microbe interactions, including their potential in the biocontrol of plant pathogenic bacteria. In this study, we investigated the tripartite interaction between, Arabidopsis thaliana, the bacterial plant pathogen Xanthomonas campestris pv. campestris (Xcc), and the lytic phage Seregon. Using meta-transcriptomic profiling, we characterized host and pathogen responses during infection and phage treatment. While a single phage treatment did not lead to the eradication of Xcc, treatment with phage Seregon significantly mitigated Xcc-induced disease symptoms, restoring leaf growth to levels comparable to the uninfected control within 14 days post-inoculation. Our data revealed that phage-mediated protection is associated with early bacterial recognition and suppression of jasmonate (JA)-related responses in the host. Analysis of nuclear localized reporter plant cell lines further confirmed a significant reduction in ROS levels in phage-treated plants. Concurrently, Xcc exhibited significant transcriptional downregulation of key virulence factors in the presence of the phage, including the genes encoding the type III secretion system, its associated effectors, and components involved in flagella biosynthesis. Remarkably, phage treatment did not lead to a significant increase in bacterial resistance to phage infection, which is in stark contrast to in vitro conditions. Taken together, this study provides first mechanistic insight into how phages can be harnessed to shape plant-pathogen interactions and highlights their potential role in enhancing plant resilience through targeted modulation of both host immunity and pathogen behaviour.
Project description:The emergence of carbapenem-resistant Acinetobacter baumannii has been increasingly reported, leading to more challenges in treating its infections. With the development of phage therapy and phage-antibiotic combinations, it is possible to improve the treatment of bacterial infections. In the present study, a vB_AbaP_WU2001 (vWU2001 for short) phage-specific CRAB was isolated and the genome size is 40,792 bp in length. The novel phage vWU2001 belongs to the Autographiviridae family and the order Caudovirales. Shotgun proteomics identified 289 proteins. The broad host range phage vWU2001 displayed a high adsorption rate, short latent period, large burst size and good stability. The phage could reduce preformed biofilms and inhibit biofilm formation. The combination of phage vWU2001 and colistin had significantly higher bacterial growth inhibition activity than that of phage, or colistin alone. The efficacy of the combined treatment was also evaluated in Galleria mellonella. The evaluation of its therapeutic potential revealed that the combination of phage and colistin showed a significantly greater increase in G. mellonella survival and clearance of bacterial number compared to that of phage or colistin alone, indicating that the combination was synergistic against CRAB. The results demonstrated that phage vWU2001 has the potential to be developed as an antibacterial agent.
Project description:To better understand host/phage interactions and the genetic bases of phage resistance in a model system relevant to potential phage therapy, we isolated several spontaneous mutants of the USA300 S. aureus clinical isolate NRS384 that were resistant to phage K. Six of these had a single missense mutation in the host rpoC gene, which encodes the RNA polymerase beta prime subunit. To examine the hypothesis that the mutations in the host RNA polymerase affect the transcription of phage genes, we performed RNA-seq analysis on total RNA samples collected from NRS384 wild-type (WT) and rpoC G17D mutant cultures infected with phage K, at different time points after infection. Infection of the WT host led to a steady increase of phage transcription relative to the host. Our analysis allowed us to define different early, middle, and late phage genes based on their temporal expression patterns and group them into transcriptional units. Predicted promoter sequences defined by conserved -35, -10, and in some cases extended -10 elements were found upstream of early and middle genes. However, sequences upstream of late genes did not contain clear, complete, canonical promoter sequences, suggesting that factors in addition to host RNA polymerase are required for their regulated expression. Infection of the rpoC G17D mutant host led to a transcriptional pattern that was similar to the WT at early time points. However, beginning at 20 minutes after infection, transcription of late genes (such as phage structural genes and host lysis genes) was severely reduced. Our data indicate that the rpoCG17D mutation prevents the expression of phage late genes, resulting in a failed infection cycle for phage K. In addition to illuminating the global transcriptional landscape of phage K throughout the infection cycle, these studies can inform our investigations into the bases of phage K’s control of its transcriptional program as well as mechanisms of phage resistance.
Project description:Single cell multi-omic readouts of both the cellular transcriptome and proteome have significantly enhanced our ability to comprehensively characterize cellular states. Most approaches in this area rely on oligonucleotide barcode-conjugated antibodies that target cell surface epitopes of interest, enabling their concomitant detection with the transcriptome. However, a similar high-throughput measurement of other cellular modalities such as the epigenome in concert with protein levels have not been described. Moreover, detection of epitopes is limited to antigens for which a specific antibody is available. Here, we introduce PHAGE-ATAC, an approach that enables the scalable and simultaneous detection of protein levels and chromatin accessibility data in single cells using the assay of transposase-accessible chromatin with sequencing (ATAC-seq). Quantitative detection of proteins by PHAGE-ATAC is accomplished through the use of engineerable nanobody-displaying phages that are genetically barcoded within the nanobody-encoding phagemids. We demonstrate the utility of PHAGE-ATAC for multimodal single cell genomic analysis in both cell lines and primary human cells. Analogous to phage display approaches, we further establish a synthetic high-complexity library of nanobody-displaying phages and demonstrate its utility to select novel antigen-specific nanobodies for PHAGE-ATAC.
Project description:Single cell multi-omic readouts of both the cellular transcriptome and proteome have significantly enhanced our ability to comprehensively characterize cellular states. Most approaches in this area rely on oligonucleotide barcode-conjugated antibodies that target cell surface epitopes of interest, enabling their concomitant detection with the transcriptome. However, a similar high-throughput measurement of other cellular modalities such as the epigenome in concert with protein levels have not been described. Moreover, detection of epitopes is limited to antigens for which a specific antibody is available. Here, we introduce PHAGE-ATAC, an approach that enables the scalable and simultaneous detection of protein levels and chromatin accessibility data in single cells using the assay of transposase-accessible chromatin with sequencing (ATAC-seq). Quantitative detection of proteins by PHAGE-ATAC is accomplished through the use of engineerable nanobody-displaying phages that are genetically barcoded within the nanobody-encoding phagemids. We demonstrate the utility of PHAGE-ATAC for multimodal single cell genomic analysis in both cell lines and primary human cells. Analogous to phage display approaches, we further establish a synthetic high-complexity library of nanobody-displaying phages and demonstrate its utility to select novel antigen-specific nanobodies for PHAGE-ATAC.
Project description:Single cell multi-omic readouts of both the cellular transcriptome and proteome have significantly enhanced our ability to comprehensively characterize cellular states. Most approaches in this area rely on oligonucleotide barcode-conjugated antibodies that target cell surface epitopes of interest, enabling their concomitant detection with the transcriptome. However, a similar high-throughput measurement of other cellular modalities such as the epigenome in concert with protein levels have not been described. Moreover, detection of epitopes is limited to antigens for which a specific antibody is available. Here, we introduce PHAGE-ATAC, an approach that enables the scalable and simultaneous detection of protein levels and chromatin accessibility data in single cells using the assay of transposase-accessible chromatin with sequencing (ATAC-seq). Quantitative detection of proteins by PHAGE-ATAC is accomplished through the use of engineerable nanobody-displaying phages that are genetically barcoded within the nanobody-encoding phagemids. We demonstrate the utility of PHAGE-ATAC for multimodal single cell genomic analysis in both cell lines and primary human cells. Analogous to phage display approaches, we further establish a synthetic high-complexity library of nanobody-displaying phages and demonstrate its utility to select novel antigen-specific nanobodies for PHAGE-ATAC.
Project description:Virulent bacteriophages (or phages) are viruses that specifically infect and lyse a bacterial host. When multiple phages co-infect a bacterial host, the extent of lysis, dynamics of bacteria-phage and phage-phage interactions are expected to vary. The objective of this study is to identify the factors influencing the interaction of two virulent phages with different Pseudomonas aeruginosa growth states (planktonic, an infected epithelial cell line, and biofilm) by measuring the bacterial time-kill and individual phage replication kinetics. A single administration of phages effectively reduced P. aeruginosa viability in planktonic conditions and infected human lung cell cultures, but phage-resistant variants subsequently emerged. In static biofilms, the phage combination displayed initial inhibition of biofilm dispersal, but sustained control was achieved only by combining phages and meropenem antibiotic. In contrast, adherent biofilms showed tolerance to phage and/or meropenem, suggesting a spatiotemporal variation in the phage-bacterial interaction. The kinetics of adsorption of each phage to P. aeruginosa during single- or co-administration were comparable. However, the phage with the shorter lysis time depleted bacterial resources early and selected a specific nucleotide polymorphism that conferred a competitive disadvantage and cross-resistance to the second phage. The extent and strength of this phage-phage competition and genetic loci conferring phage resistance, are, however, P. aeruginosa genotype dependent. Nevertheless, adding phages sequentially resulted in their unimpeded replication with no significant increase in bacterial host lysis. These results highlight the interrelatedness of phage-phage competition, phage resistance and specific bacterial growth state (planktonic/biofilm) in shaping the interplay among P. aeruginosa and virulent phages.