Biology subjects

Sharma, V.

Publications and source records attributed to Sharma, V..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

Chenodeoxycholic Acid Modulation via Bacteroides intestinalis AM1 underscores a Novel Approach in Acute Liver Failure

BackgroundAcute liver failure (ALF) is associated with rapid and progressive hepatocellular injury, and severe metabolic-microbial derangements. We investigated early metabolic markers of non-survival, and a potential microbial intervention using Bacteroides intestinalis-AM1, to improve outcomes in ALF. MethodPlasma metabolomics and meta-proteomics were performed in 40 ALF patients and 5 healthy controls (training cohort). A non-survival marker panel was identified and validated in 270 ALF patients (test cohort) using high resolution mass spectrometry and machine learning. It was functionally validated in acetaminophen-induced ALF mouse model. B. intestinalis-AM1 was used to study alteration of gut bacteria and amelioration of liver injury. ResultsALF non-survivors showed a distinct metabolomic signature with elevated primary bile acids {chenodeoxycholic acid (CDCA), cholic acid (CA)}, tryptophan, tyrosine, and enrichment of pathways linked to inflammation, cell death, and stress response (p<0.01, FDR<0.01, FC>1.5). Non-survivors had higher alpha/beta diversity (p<0.05) with increase in Proteobacteria, Firmicutes, Actinobacteria (p<0.05); functionally associated with energy, amino acid and xenobiotic metabolism (p<0.05). A gut microbiota derangement in converting primary to secondary bile acids was evident as CDCA and cytotoxic metabolites (4-(2-Amino phenyl)-2,4-dioxobutanoate, L-Tyrosine) were higher. Elevated CDCA (logFC>10) levels correlated with mortality in ALF patients as well as in mouse model. In the later, administration of B. intestinalis-AM1 bacteria, (10^9) reduced CDCA and CA levels by enhancing FXR, FGF15, SLC10A1 gene expression, attenuating inflammation (IL-1beta, TLR4-signalling), necroptosis, and modulating glutathione(oxidative-repair), tryptophan(inflammation), and histidine (tissue repair) metabolism. ConclusionHigh levels of chenodeoxycholic acid (CDCA) represent a poor prognostic indicator in ALF patients. B. intestinalis-AM1, a primary-to-secondary bile acid converter, effectively reduce CDCA levels, activated FXR, reduced inflammation and protected hepatocytes, highlighting its therapeutic potential in ALF.

microbiology↗

bioRxiv2025

Impacts of competition and phenotypic plasticity on the viability of adaptive therapy

Cancer is heterogeneous and variability in drug sensitivity is widely documented across cancer types. Adaptive therapy is an emerging modality of cancer treatment that leverages this drug resistance heterogeneity to improve therapeutic outcomes. Current standard treatments typically eliminate a large fraction of drug-sensitive cells, leading to drug-resistant relapse due to competitive release. Adaptive therapy aims to retain some drug-sensitive cells, thereby limiting resistant cell growth by ecological competition. While early clinical trials of such a strategy have shown promise, optimisation of adaptive therapy is a subject of active study. Current methods largely assume cell phenotypes to remain constant, even though cell-state transitions could permit drug-sensitive and -resistant phenotypes to interchange and thus escape therapy. We address this gap using a deterministic model of population growth, in which sensitive and resistant cells grow under competition and undergo cell-state transitions. Based on the models steady-state behaviour and temporal dynamics, we identify distinct balances of competition and phenotypic transitions that are suitable for effective adaptive versus constant dose therapy. Our data indicate that under adaptive therapy, models with cell-state transitions show a higher frequency of fluctuations than those without, suggesting that the balance between ecological competition and phenotypic transitions could determine population-level dynamical properties. Our analyses also identify key limitations of applying phenomenological models in clinical practice for therapy design and implementation, particularly when cell-state transitions are involved. These findings provide an overall perspective on the relevance of phenotypic plasticity for emerging cancer treatment strategies using population dynamics as an investigation framework. Significance StatementDrug-sensitive and -resistant cancer cells can compete with each other within the same tumour, and adaptive therapy exploits this competition to control overall tumour growth. The fact that sensitive and resistant cell types can switch phenotypes complicates the implementation of adaptive therapy. Our ODE-based theoretical ecology framework shows that asymmetric competition favouring sensitive cells generally benefits therapy outcomes, while phenotypic plasticity is usually detrimental. Our model also provides cell population-level indicators that can help predict the underlying balance between competition and plasticity. Phenomenological models are limited by whether their parameters can be reliably identified given scarce data, and our study illuminates the scope of such models in understanding cancer population dynamics and the need for mechanistic modelling.

systems biology↗

bioRxiv2025

Cucumber extracellular vesicles-localized tetraspanin and phloem protein 2 mediates the cross-kingdom trafficking of a pathogenic non-coding RNA

The plant apoplast and extracellular vesicles (EVs) contain diverse RNA species, including small RNAs, long non-coding RNAs, and circular RNAs, many of which cross kingdom boundaries through EV-mediated transport. Viroid RNAs--pathogenic circular non-coding RNAs--are known to move from plants to fungi and insects, though the mechanism remains unclear. Using apple scar skin viroid (ASSVd) and cucumber as a host, we demonstrate that viroid RNAs in circular, linear, and small RNA forms are present in cucumber EVs. ASSVd RNA exhibits features of extracellular RNAs, such as m6A methylation and five EXOmotifs. Through mass spectrometry and immunoblotting, we identify tetraspanin 8 (CsTET8) as a conserved EV marker and report CsPP2, a phloem lectin with an RNA-binding domain, as a novel EV-associated protein. RNA co-immunoprecipitation and immuno-enrichment assays reveal that CsPP2 and ASSVd co-localize in CsTET8-positive EVs, with direct interactions between CsPP2-CsTET8 and CsPP2-ASSVd. We propose CsPP2 functions as an RNA-sorting protein that mediates RNA loading into EVs. Further, we show that whiteflies can acquire ASSVd via EVs and transmit it to healthy plants, indicating a cross-kingdom transmission route. These findings establish viroid RNAs as a model system to study the molecular basis of RNA trafficking across biological kingdoms.

plant biology↗

bioRxiv2025

Amino acid repeat signatures underlying human-pathogen interactions

Emerging evidence suggests that amino acid homorepeats (HRs) in proteins (HRPs) contribute to protein interactability. What is the role of HRs in human-pathogen protein interactions? We find that pathogens engage physiologically important human HRPs, thereby affecting diverse host physiological processes. From the pathogen standpoint, (i) eukaryotic pathogens engage more HRPs but with host-sparse HRs, leading to disparate and discriminate interactions, (ii) prokaryotic pathogens engage less HRPs but with host-abundant non-polar HRs via host protein proxies bringing about discriminate or promiscuous interactions and (iii) viral pathogens engage more HRPs with host-abundant polar uncharged HRs affecting promiscuous interactions using host-partner HR tract mimicry. To propel further research, we introduce a resource Hi-PHI (http://hiphi.iisertirupati.ac.in/) cataloging critical information about human and pathogen HRPs and HRs. We propose mechanisms to (i) repurpose drugs targeting human HRPs engaged by pathogens for treating different infections and (ii) exploit HRs and their flanks as targets for pathogen-targeted anti-infectives.

systems biology↗

bioRxiv2025

Glassy Adhesion Dynamics Govern Transitions Between Sub-Diffusive and Super-Diffusive Cell Migration on Viscoelastic Substrates

Cell migration is pivotal in cancer metastasis, where cells navigate the extracellular matrix (ECM) and invade distant tissues. While the ECM is viscoelastic--exhibiting time-dependent stress relaxation--its influence on cell migration remains poorly understood. Here, we employ an integrated experimental and modeling approach to investigate filopodial cancer cell migration on viscoelastic substrates and uncover a striking transition from sub-diffusive to super-diffusive behavior driven by the substrates viscous relaxation timescale. Conventional motor-clutch based migration models fail to capture these anomalous migration modes, as they overlook the complex adhesion dynamics shaped by broad distribution of adhesion lifetimes. To address this, we develop a glassy motor-clutch model that incorporates the rugged energy landscape of adhesion clusters, where multiple metastable states yield long-tailed adhesion timescales. Our model reveals that migration dynamics are governed by the interplay between cellular and substrate timescales: slow-relaxing substrates prolong trapping, leading to sub-diffusion, while fast-relaxing substrates promote larger steps limiting trapping, leading to super-diffusion. Additionally, we uncover the role of actin polymerization and contractility in modulating adhesion dynamics and driving anomalous migration. These findings establish a mechanistic framework linking substrate viscoelasticity to cell motility, with implications for metastasis and cancer progression.

biophysics↗

bioRxiv2025

DZNep-induced single point mutation (M236I) in poxviral 2'-O-methyltransferase enhances mRNA stability and translation efficiency

Poxviruses encode two highly conserved S-adenosylmethionine (SAM)-dependent methyltransferases for mRNA capping. While D1L facilitates translation via cap-0 formation, the role of VP39-mediated cap-1 modification has been canonically restricted to shield viral mRNA from cytoplasmic pattern-recognition receptors (PRRs). Here, we uncover a novel function of VP39 by demonstrating that prolonged exposure to the SAM cycle inhibitor DZNep selected a virus escape mutant harbouring a point mutation (M236I) in VP39. VP39_mut bypasses S-adenosylhomocysteine (SAH)-mediated feedback inhibition, enhancing 2-O-methylation of viral transcripts and promoting their association with active translation machinery. Consequently, VP39_mut significantly improves viral protein translation, replicative fitness, and yields across species. Notably, VP39_mut-capped in vitro transcribed (IVT) mRNA exhibited [~]2.7-fold higher protein expression compared to VP39_wt, the standard tool for IVT applications. These findings reveal a unique resistance mechanism and provide critical insights into poxvirus mRNA biology while underscoring the potential of optimized VP39 for advancing mRNA-based therapeutics and vaccine production.

microbiology↗

bioRxiv2025

Distinct filament morphology and membrane tethering features of the dual FtsZs in Odinarchaeota

The deep-branching Asgard archaea have emerged as a model to study Eukaryogenesis as they harbor homologs of many of the major eukaryotic protein families. In this study, we use Candidatus Odinarchaeota FtsZs as representatives to understand the probable origin, evolution, and assembly of the FtsZ-Tubulin protein superfamily in Asgard archaea. We have performed a comparative analysis of the biochemical properties and cytoskeletal assembly of FtsZ1 and FtsZ2, the two FtsZ isoforms in the Odinarchaeota metagenome. Our electron microscopy analysis reveals that OdinFtsZ1 assembles into curved single protofilaments, while OdinFtsZ2 forms stacked spiral ring-like structures. Upon sequence analysis, we identified an N-terminal amphipathic helix in OdinFtsZ1, which mediates direct membrane tethering. In contrast, OdinFtsZ2 is recruited to the membrane by the membrane-anchor OdinSepF via OdinFtsZ2s C-terminal tail. Overall, we report the presence of two distant evolutionary paralogs of FtsZ in Odinarchaeota, with distinct filament assemblies and differing modes of membrane targeting mechanisms, namely direct vs SepF-mediated membrane binding. Our findings highlight the diversity of FtsZ proteins in the transitional archaeal phylum Odinarchaeota, providing valuable insights into the evolution and differentiation of tubulin family proteins.

biochemistry↗

bioRxiv2025

Anticancer synthetic arylsulfonamides with Wnt1-modulating activity

Dysregulation of the Wnt1/{beta}-catenin signaling pathway has been demonstrated to be a driving factor in the propagation of several human cancers. Previous studies have discovered methyl 3-{[(4-methylphenyl)sulfonyl]amino}benzoate (MSAB) as a selective inhibitor of the Wnt1/{beta}-catenin signaling pathway, which putatively functions through direct engagement of {beta}-catenin. To understand how changes to the identity and position of the methyl ester affect the in vitro potency of this compound in Wnt1-driven mammalian cell lines, we prepared and evaluated three analogs of MSAB with 3- and 4-substituted methyl and ethyl esters. In MTT assays, analogs with methyl esters showed significantly more activity than their ethyl ester counterparts and both 4-substituted esters exhibited significantly attenuated antiproliferative activity, with MSAB exhibiting dose-dependent activity across cancerous cell lines. Further analysis by flow cytometry reveals low-Annexin V signal, suggesting that these compounds do not function via a pro-apoptotic pathway. Additionally, through a TCF/LEF-activated luciferase reporter cell assay, we observe that the 4-substituted methyl ester analogous to MSAB exhibits slightly diminished Wnt1-inhibitory activity, while 3- and 4-substituted ethyl esters exhibit minimal Wnt1-inhibitory activity. This difference in potency with a simple ester substitution might be attributed to several factors that ultimately drive antiproliferative activity, prompting the investigation of other potential substituents to further investigate the structure-activity relationship of these compounds as Wnt1-based antiproliferative agents.

cancer biology↗

bioRxiv2025

Mesoscale landscaping of the TRIM protein family reveals a novel human condensatopathy

The mesoscale organization of cells is central to cellular physiology and pathology. Cellular condensates often form via biomolecular phase separation, mediated by intrinsically disordered regions (IDRs) and represent a key mechanism for mesoscale organization. The TRI-partite Motif (TRIM) family of ubiquitin ligases is implicated in diverse cellular functions and disease, yet the role of biomolecular condensation in TRIM family organization remains understudied. Here, we systematically investigate the mesoscale localization of 72 TRIM proteins, revealing that a majority form condensates in distinct cellular compartments. IDR content correlates with dynamic condensate formation, suggesting a critical role in mesoscale organization. Focusing on TRIM8, associated with a neuro-renal disorder, we demonstrate that disease-causing truncations of the TRIM8 C-terminal IDR result in a condensatopathy, characterized by disrupted condensation, proteasomal regulation, and TAK1/NF{kappa}B signaling. Functional assays in cellular and animal models link these disruptions to podocyte dysfunction and impaired response to injury. Our findings establish a framework for understanding condensatopathies and the mesoscale principles governing TRIM family organization and function.

cell biology↗

bioRxiv2024

Conformational dynamics of a histidine molecular switch in a cation/proton antiporter

Multisubunit Mrp type sodium proton (Na+/H+) antiporters are indispensable for the growth of alkali and salt tolerant bacteria and archaea under challenging conditions. Several subunits of the membrane protein complex are closely related to the membrane bound subunits of mitochondrial respiratory complex I, a key enzyme in aerobic energy metabolism. The molecular mechanism of ion translocation by complex I and Mrp antiporters has remained largely unknown and is the subject of intense debate. Here, we combine the power of site-directed mutagenesis and large-scale atomistic molecular dynamics simulations to elucidate the molecular basis of proton-conducting function of the MrpA subunit of the antiporter. We show that point mutations directly affect the transport activity by perturbing the conformational dynamics of a key histidine residue that acts as a molecular switch. Importantly, we find that charge and protonation state variations drive hydrogen bonding rearrangements and hydration changes, which result in coupled sidechain and backbone level conformational changes of the histidine and neighboring residues. We propose the histidine switch as a unique functional element central to proton transport function in Mrp antiporters and respiratory complex I. Significance statementEnergy conversion in biology is catalyzed by several membrane-bound enzyme complexes that drive transmembrane charge translocation. A key question is how these charges are moved against a membrane gradient in an efficient manner, i.e., what kind of gating and fail-safe mechanisms are employed by the proteins to ensure charge transfer directionality. By studying cation/proton Mrp antiporter, which shares homology with the mitochondrial complex I, we describe a conserved histidine residue acting as a molecular switch crucial for gating transfer of protons. Our work emphasizes the functional significance of conserved and conformationally mobile motifs in proteins. The results will benefit the mechanistic understanding of naturally existing proteins and design of artificial enzymes.

biophysics↗

bioRxiv2024

Immunogenic shift of arginine metabolism triggers systemic metabolic and immunological reprogramming to prevent HER2+ breast cancer

Arginine metabolism in tumors is often shunted into the pathway producing pro-tumor and immune suppressive polyamines (PAs), while downmodulating the alternative nitric oxide (NO) synthesis pathway. Aiming to correct arginine metabolism in tumors, arginine deprivation therapy and inhibitors of PA synthesis have been developed. Despite some therapeutic advantages, these approaches have often yielded severe side effects, making it necessary to explore an alternative strategy. We previously reported that supplementing SEP, the endogenous precursor of BH4 (the essential NO synthase cofactor), could correct arginine metabolism in tumor cells and tumor-associated macrophages (TAMs) and induce their metabolic and phenotypic reprogramming. We saw that oral SEP treatment effectively suppressed the growth of HER2-positive mammary tumors in animals. SEP also has no reported dose-dependent toxicity in clinical trials for metabolic disorders. In the present study, we report that a long-term use of SEP in animals susceptible to HER2-positive mammary tumors effectively prevented tumor occurrence. These SEP-treated animals had undergone reprogramming of the systemic metabolism and immunity, elevating total T cell counts in the circulation and bone marrow. Given that bone marrow-resident T cells are mostly memory T cells, it is plausible that chronic SEP treatment promoted memory T cell formation, leading to a potent tumor prevention. These findings suggest the possible roles of the SEP/BH4/NO axis in promoting memory T cell formation and its potential therapeutic utility for preventing HER2-positive breast cancer.

cancer biology↗

bioRxiv2024

An envelope stress response governs long-chain fatty acid metabolism via a small RNA to maintain redox homeostasis in Escherichia coli

Long-chain fatty acids (LCFAs) are a tremendous source of energy for several bacteria but are complex to use because they induce redox stress. We previously showed that LCFA degradation impedes oxidative protein folding in the Escherichia coli envelope, an issue that arises due to the insufficiency of ubiquinone, a lipid-soluble electron carrier in the electron transport chain (ETC). To maintain redox homeostasis, E. coli activates the CpxAR two-component system; however, the nature of feedback imparted by this envelope stress response (ESR) remained unknown. Here, we show that contrary to the well-recognized remedial mode of Cpx restoring envelope integrity by upregulating protein quality control factors, in LCFA-grown cells, it uses a preventive measure to maintain homeostasis. Cpx increases ubiquinone availability for oxidative protein folding by suppressing LCFA metabolism and directly increasing ubiquinone levels. Further, rather than using its conventional mode of imparting regulation via CpxR working as a transcriptional regulator, during LCFA metabolism, Cpx mainly uses its non-coding arm to counteract envelope redox stress. The Cpx-regulated small RNA CpxQ represses fad genes involved in LCFA transport and {beta}-oxidation, downregulates components of glyoxylate shunt, gluconeogenesis, and ETC, and increases ubiquinone content. Corroborating with its role in repressing LCFA metabolism and maintaining redox homeostasis, CpxQ overexpression impairs growth of E. coli in LCFAs and CpxQ deletion renders LCFA-grown E. coli hypersensitive to a thiol agent. Our foremost work studying the interconnection between LCFA metabolism, redox stress, and ESR in E. coli provides a rationale for investigating similar networks in other LCFA-utilizing bacteria. Significance StatementLong-chain fatty acids (LCFAs) are energy-rich nutrients for Escherichia coli; however, their utilization hampers disulfide bond (DSB) formation in secreted proteins, an essential process that occurs in the envelope compartment. Here, we show that an envelope stress response manipulates LCFA metabolism in E. coli and uses a small RNA (sRNA) to restore homeostasis. Several bacteria with a huge impact on human health use host-derived LCFAs during infection. Because many virulence factors require DSB formation, the present study offers a basis to examine whether sRNAs play a role in governing envelope redox balance during LCFA metabolism in pathogens. The sRNA-mediated control is likely an ideal strategy both for rapid response to and quick recovery from LCFA-induced stress.

microbiology↗

bioRxiv2024

Multimodal learning of transcriptomes and text enables interactive single-cell RNA-seq data exploration with natural-language chats

Single-cell RNA-seq characterizes biological samples at unprecedented scale and detail, but data interpretation remains challenging. Here we introduce CellWhisperer, a multimodal machine learning model and software that connects transcriptomes and text for interactive single-cell RNA-seq data analysis. CellWhisperer enables the chat-based interrogation of transcriptome data in English language. To train our model, we created an AI-curated dataset with over a million pairs of RNA-seq profiles and matched textual annotations across a broad range of human biology, and we established a multimodal embedding of matched transcriptomes and text using contrastive learning. Our model enables free-text search and annotation of transcriptome datasets by cell types, states, and other properties in a zero-shot manner and without the need for reference datasets. Moreover, Cell-Whisperer answers questions about cells and genes in natural-language chats, using a biologically fluent large language model that we fine-tuned to analyze bulk and single-cell transcriptome data across various biological applications. We integrated CellWhisperer with the widely used CELLxGENE browser, allowing users to in-teractively explore RNA-seq data through an integrated graphical and chat interface. Our method demonstrates a new way of working with transcriptome data, leveraging the power of natural language for single-cell data analysis and establishing an important building block for future AI-based bioinformatics research assistants.

bioinformatics↗

bioRxiv2024

Comet fragment-ion indexing for enhanced peptide sequencing

Fragment ion indexing has significantly improved the efficiency of proteomics database search tools. This work implements fragment ion indexing in Comet, a widely-used, open-source search engine. We demonstrate that this enhancement maintains scoring and identification accuracy while substantially increasing peptide spectral matching speeds across multiple applications, including open modification searches, immunopeptidomics, and real-time searches. Comet-FI reduced search speeds by up to 94%, enabling the rapid analysis of complex data types like immunopeptidomes. Fragment-ion indexing enables Comet to keep pace with modern instrumentation and expanding applications in proteomics, reinforcing its utility in diverse proteomics workflows and its integration with a wide range of proteomics tools and platforms.

bioinformatics↗

bioRxiv2024

Catalytic relevance of quinol anion in biological energy conversion by respiratory complex I

Redox chemistry of quinones is an essential component of life on earth. In the mitochondrial electron transport chain, ubiquinone molecule is reduced to ubiquinol by respiratory complex I to drive the synthesis of ATP. By performing both classical and hybrid QM/MM simulations on high-resolution cryo-EM structures, including quantitative free energy calculations, we show that semiquinone species in complex I is anionic in nature and is trapped in the active site chamber for its subsequent reduction. Two-electron reduction of ubiquinone yields a metastable ubiquinol anion, which is electrostatically pushed by 15-20 [A] towards the exit of the ubiquinone binding chamber to drive the proton pump of complex I. As part of the two-electron reduction of ubiquinone, protonic rearrangements take place in the active site in which a highly conserved histidine converts from its one tautomeric state to another. The combined findings provide a detailed and testable mechanistic picture of proton-coupled electron transfer reaction at the active site of complex I in wild-type as well as mutant conditions.

biochemistry↗

bioRxiv2024

Correlating amino acid profiles with improved expression capability of superior CHO based expression platforms

A novel modified CHO cell line was constructed by expressing a three gene combination of Bclx(L), Aven and BECN1 which are critical targets of the apoptosis and autophagy pathways. This synergistic combination significantly improved cell viability as well as Rituximab (RTX) expression by 7.5 fold. A comparative amino acid analysis of the modified and control cultures both with and without RTX expression showed interesting changes in amino acid uptake rates. We first compared the utilization of amino acids in the control cells without RTX expression to the control cells with RTX expression where it declined significantly in the later half of the culture with the maximum decrease observed with tyrosine, which instead of uptake got secreted into the medium. The uptake of aspartic and glutamic acid also fell drastically during this period demonstrating the deleterious effect of RTX expression on cellular health. When the modified cells were used for RTX expression, there was conversely a slight increase in amino acid consumption in the later part of the culture with the maximum increase observed with alanine and tyrosine. The differential amino acid consumption rates provided us with an indirect measure of improved cellular health and ability of the modified cells to counter the cellular stress associated with RTX expression. Amino acid analysis could thus become a useful predictive tool to identify the critical features of better host expression platforms.

bioengineering↗

bioRxiv2024

A comparison of super-resolution microscopy techniques for imaging tightly packed microcolonies of an obligate intracellular bacterium

Conventional optical microscopy imaging of obligate intracellular bacteria is hampered by the small size of bacterial cells, tight clustering exhibited by some bacterial species and challenges relating to labelling such as background from host cells, a lack of validated reagents, and a lack of tools for genetic manipulation. In this study we imaged intracellular bacteria from the species Orientia tsutsugamushi (Ot) using five different fluorescence microscopy techniques: standard confocal, Airyscan confocal, instant Structured Illumination Microscopy (iSIM), three-dimensional Structured Illumination Microscopy (3D-SIM) and Stimulated Emission Depletion Microscopy (STED). We compared the ability of each to resolve bacterial cells in intracellular clumps in the lateral (xy) axis, using full width half maximum (FWHM) measurements of a labelled outer membrane protein (ScaA) and the ability to detect small, outer membrane vesicles external to the cells. We next compared the ability of each technique to sufficiently resolve bacteria in the axial (z) direction and found 3D-STED to be the most successful method for this. We then combined this approach with a custom 3D cell segmentation and analysis pipeline using the open-source, deep learning software, Cellpose to segment the cells and subsequently the commercial software Imaris to analyze their 3D shape and size. Using this combination, we demonstrated differences in bacterial shape, but not their size, when grown in different mammalian cell lines. Overall, we compare the advantages and disadvantages of different super-resolution microscopy techniques for imaging this cytoplasmic obligate intracellular bacterium based on the specific research question being addressed.

microbiology↗

bioRxiv2024

The TyphiNET data visualisation dashboard: Unlocking Salmonella Typhi genomics data to support public health

BackgroundSalmonella enterica subspecies enterica serovar Typhi (abbreviated as Typhi) is the bacterial agent of typhoid fever. Effective antimicrobial therapy reduces complications and mortality; however, antimicrobial resistance (AMR) is a major problem in many endemic countries. Prevention through vaccination is possible through recently-licensed Gavi-supported typhoid conjugate vaccines (TCVs), and national immunisation programs are currently being considered or deployed in several countries where AMR prevalence is known to be high. Pathogen whole genome sequence data are a rich source of information on Typhi variants (genotypes or lineages), AMR prevalence, and mechanisms. However, this information is currently not readily accessible to non-genomics experts, including those driving vaccine implementation or empirical therapy guidance. ResultsWe developed TyphiNET (https://www.typhi.net), an interactive online dashboard for exploring Typhi genotype and AMR distributions derived from publicly available pathogen genome sequences. TyphiNET allows users to explore country-level summaries such as the frequency of pathogen lineages, temporal trends in resistance to clinically relevant antimicrobials, and the specific variants and mechanisms underlying emergent AMR trends. User-driven plots and session reports can be downloaded for ease of sharing. Importantly, TyphiNET is populated by high-quality genome data curated by the Global Typhoid Pathogen Genomics Consortium, analysed using the Pathogenwatch platform, and identified as coming from non-targeted sampling frames that are suitable for estimating AMR prevalence amongst Typhi infections (no personal data is included in the platform). As of February 2024, data from a total of n=11,836 genomes from 101 countries are available in TyphiNET. We outline case studies illustrating how the dashboard can be used to explore these data and gain insights of relevance to both researchers and public health policy-makers. ConclusionsThe TyphiNET dashboard provides an interactive platform for accessing genome-derived data on pathogen variant frequencies to inform typhoid control and intervention strategies. The platform is extensible in terms of both data and features, and provides a model for making complex bacterial genome-derived data accessible to a wide audience.

microbiology↗