Biology subjects

Singh, A.

Publications and source records attributed to Singh, A..

At least 37 records · Page 2Linked to original sources

bioRxiv2026

E3 ubiquitin ligase SYVN1 mediates K63-linked ubiquitination of DDX3X to activate Macrophage NLRP3 Inflammasome

DDX3X (DEAD box helicase 3, X linked) is a common and essential component for both stress granules and NLRP3 inflammasome assembly and their activation; however, the upstream cellular stress signals driving DDX3X to activate the contrasting cellular pathway remain unclear. We identified the pivotal role of the E3 ubiquitin ligase SYVN1(Synoviolin) as the upstream regulator of DDX3X and thereby controlling NLRP3 activation and stress granule assembly. We observed SYVN1 silencing in macrophages prevented both NLRP3 driven inflammation and stress granule formation. SYVN1 deficiency prevented LPS induced inflammatory lung injury and increased the survival rate of the mice. SYVN1 sustains DDX3X gene expression and promotes stimulus-dependent ubiquitination of DDX3X. Under inflammatory conditions, SYVN1 mediated 63 linked ubiquitination of DDX3X, a requirement for NLRP3 inflammasome activation. Conversely, stress conditions reduced K63 linked DDX3X ubiquitination in coordination with activity of the deubiquitinase OTUB1 (OTU domain-containing ubiquitin aldehyde-binding protein 1). Thus, the balance between SYVN1 and OTUB1 functioned to optimize DDX3X activity and activation of NLRP3 or stress granule. These findings show the upstream role of SYVN1 OTUB1 axis in integrating cellular stress signals to decide the cell fate and suggest that ubiquitination of DDX3X is a potential target for inflammasome driven inflammation.

immunology↗

bioRxiv2026

Elexacaftor/tezacaftor/ivacaftor treatment is associated with epigenetic age deceleration in cystic fibrosis

Background: Cystic fibrosis (CF) is associated with chronic inflammation and progressive multisystem disease, which may contribute to accelerated biological aging. Elexacaftor/tezacaftor/ivacaftor (ETI) substantially improves clinical outcomes in people with CF (pwCF), but its effects on epigenetic aging and their relationship with inflammation remain poorly understood. Methods: We performed a pilot longitudinal study of 8 modulator-naive pwCF. Blood DNA methylation was profiled before ETI initiation and after 1 year of treatment. DNAmGrimAge2 age acceleration was calculated adjusting for chronological age and blood cell composition. Associations with inflammatory biomarkers and clinical measures were assessed using repeated measures correlation. Results: DNAmGrimAge2 was strongly correlated with chronological age at baseline and follow-up. DNAmGrimAge2 age acceleration decreased after ETI treatment, from a median of 1.92 years before treatment to -1.70 years after 1 year (p=0.008). Greater age acceleration was associated with higher IL-6, IL-1{beta}, and calprotectin concentrations. Higher FEV1pp was associated with lower age acceleration, whereas higher sweat chloride was associated with greater age acceleration. Conclusions: DNAmGrimAge2 age acceleration decreased following ETI initiation and was associated with markers of innate and neutrophilic inflammation and CF disease activity. These findings suggest that epigenetic aging in CF may be dynamic and responsive to improvements in CFTR function and inflammatory disease burden. Larger longitudinal studies are needed to validate these findings and determine their relationship with long-term clinical outcomes.

genetics↗

bioRxiv2026

An adenylyl cyclase switch reroutes carbon from growth to virulence lipids in Mycobacterium tuberculosis

Anti-TB drugs act non-uniformly on Mycobacterium tuberculosis (Mtb) because of its distinct physiological states across diverse infection niches shaped by host-derived nutrients and stresses. Agonists of the adenylyl cyclase Rv1625c are a novel drug class that selectively inhibits Mtb growth in macrophages and cholesterol-rich conditions by an unknown mechanism. Combining condition-resolved transcriptomics, genome-scale metabolic modeling, and genetic perturbation, we show these agonists cause a blockade in the electron transport chain, which likely activates Rv1625c. The elevated cAMP in turn drives global transcriptional and post-translational remodeling of central carbon and lipid metabolism. The resulting methylcitrate cycle reversal chokes cholesterol breakdown products from entering central metabolism, diverting carbon toward cell wall and virulence-lipid (phthiocerol dimycocerosate) synthesis and inhibiting growth. These drugs thus hijack an endogenous switch that reroutes carbon from biomass to virulence-lipid production. Hence, nutrients that restore carbon flux and relieve ETC blockade reduce activity, whereas Rv1625c overexpression and ETC inhibitors potentiate drug action even in refractory conditions.

systems biology↗

bioRxiv2026

Insulators As Dynamic, Tunable Regulators of Enhancer-Promoter Coordination in Living Drosophila Embryos

The three-dimensional organization of the genome enables enhancers and promoters to interact across vast distances and direct transcription. Yet whether architectural elements, such as insulators, serve as rigid, passive barriers or as dynamic, active organizers of this communication remains unclear. Here, using single-cell, live imaging of a Drosophila transgene in which a single enhancer regulates two equidistant promoters, we confirm that the enhancer engages both promoters simultaneously and show that coordinated bursting is intrinsically more productive than uncoordinated activity. Flanking this system with insulators increases coordinated bursting frequency and transcriptional output, indicating that insulator-mediated looping promotes multi-way enhancer-promoter interaction. Further, bidirectionally-paired, homotypic insulators produce stronger coordination than unidirectional pairs. Inserting an intermediate insulator to generate competing loop configurations, together with two-state promoter modeling, we show that these chromatin loops are highly dynamic. This work reframes insulators as active, tunable regulators that shape the frequency, coordination, and productivity of enhancer-promoter communication.

molecular biology↗

bioRxiv2026

Environment-Aware DNA Language Model for Stress-Responsive Genomic Prioritization in Maize

Abiotic stresses such as heat and drought severely reduce maize productivity, yet identifying genomic regions that confer stress resilience remains a challenge. Inspired by advances in Large Language Models (LLMs), Genomic Foundation Models (GFMs) have recently emerged as a promising approach for capturing regulatory patterns through large-scale pre-training on DNA sequences. However, their application to plant stress-response analysis remains unexplored. This study presents an environment-aware DNA-LLM that adapts AgroNT, a transformer-based GFM pre-trained on diverse plant genomes, by incorporating stress-specific prompt tokens. Through parameter-efficient fine-tuning, the model learns stress-conditioned sequence representations that form distinct clusters in the embedding space across environmental contexts. By combining stress-induced shifts in these sequence representations relative to control conditions with transformer attention patterns, we prioritized putative heat- and drought-responsive genomic regions associated with grain yield in the Genomes-to-Fields (G2F) panel. Prioritized regions were supported by spatiotemporal differential gene-expression evidence and overlap with stress-associated quantitative trait loci. They were further characterized through transcription-factor family analysis and regulatory motif enrichment. Attention-guided analysis additionally identified stress-associated motifs enriched within model-emphasized sequence regions. Overall, the prioritized loci were proximal to genes involved in transcriptional regulation, signaling, and metabolic pathways relevant to abiotic-stress adaptation, demonstrating the potential of stress-conditioned transformer-based sequence modeling for environment-aware genome-to-phenome analysis.

genomics↗

bioRxiv2026

Dengue virus-induced thrombocytopenia is mediated by dysregulation of the RUNX1-MYH9 axis

Dengue virus (DENV) infection causes an acute febrile illness that is usually self-limiting but can become fatal. Thrombocytopenia, or a decrease in circulating platelets, is a major clinical feature of dengue and is strongly associated with the progression to dengue hemorrhagic fever and dengue shock syndrome. In this report, MYH9, a cytoskeletal protein involved in platelets maturation and release, was found to be down-regulated in DENV-infected Huh7 cell lines. The expression of RUNX1, an important transcription factor involved in megakaryopoiesis, was also decreased following DENV-infection. In-silico analysis identified three potential RUNX1 transcription-factor binding site in the promoter-region of MYH9 gene. We therefore investigated whether RUNX1 regulates MYH9 expression during DENV-infection. Luciferase-assay and ChIP assays showed that DENV-infection affect the binding of RUNX1 to the MYH9 promoter, providing insight into the molecular basis underlying the reduced expression of MYH9 expression. Furthermore, the megakaryocyte differentiation markers GATA1, ITGB3, and MYH9 were upregulated in PMA-induced K562-cells. However, DENV infection downregulated these genes and increased the expression of apoptosis marker gene CYCS. These findings suggest that the dengue affects megakaryopoiesis through multiple mechanisms, potentially reducing platelets production while also promoting platelets destruction. Additionally, Fluorescence and electron microscopy revealed that functional defects of MYH9 may affects megakaryopoiesis biogenesis. Overall, this study provides insights into the molecular mechanisms contributing to thrombocytopenia during DENV infection.

molecular biology↗

bioRxiv2026

P. aeruginosa liquid-based pathogenesis triggers HLH-30-dependent metabolic rewiring in C. elegans

Innate immunity is the first line of defense against invading pathogens and is essential for maintaining host survival. While the majority of innate immunity studies have focused on pathogen recognition and antimicrobial responses, increasing evidence suggests that lipid metabolism plays a fundamental role in shaping immune function. Understanding how these metabolic pathways contribute to immunity is crucial in the context of bacterial infections caused by opportunistic pathogens such as Pseudomonas aeruginosa. Host defense against P. aeruginosa requires the coordination of innate immune and metabolic responses; however, the mechanisms linking lipid metabolism to pathogen resistance remain poorly understood. Research into the relationship between lipid homeostasis and innate immunity may reveal factors governing host-pathogen interactions and identify novel strategies to enhance resistance to infection. Here, we demonstrate that P. aeruginosa liquid-based pathogenesis (LK-Pa) triggers a shift in host metabolism which differs from the one observed in response to agar-based pathogenesis. Our bioinformatic analyses revealed a highly similar metabolic profile (enrichment of lipid metabolism) in worms exposed to LK-Pa or the iron chelator phenanthroline, suggesting a shared host response to iron deprivation. We further characterized the host genetic factors driving this metabolic shift and established their importance for host defense against LK-Pa as well as liquid-based pathogenesis by Gram-positive pathogens Enterococcus faecalis and Staphylococcus aureus. Notably, our results indicate that LK-Pa triggers host lipid droplet depletion, an upstream component that leads to increased {beta}-oxidation. Finally, we demonstrate that LK-Pa triggers repression of MXL-3 which results in HLH-30-dependent metabolic rewiring.

cell biology↗

bioRxiv2026

Retrieval uncertainty drives rapid consolidation of confabulated memories in retrosplenial cortex

Learning to make associations in the absence of direct reinforcement, based on previous memories of reward or punishment, is an evolutionary trait quintessential for survival. Little is known about if such higher order associations (HOA) can lead to fabrication of new memories for unreal events. We probed if uncertainty during retrieval of old memory representations can trigger such confabulation. Using chemogenetics, in vivo imaging, and behavior we show that uncertainty in memory perception can not only transfer conditioning to hitherto unexperienced novel context but also can get rapidly consolidated. We find while acquisition of HOA require dorsal-CA1 parvalbumin interneuron activity in intact hippocampus, retrieval requires retrosplenial cortex (RSc). We develop an automated Large-scale Brainwide Correlated Activity Mapping (LaBCAM) method to identify functional connectivity changes across different brain regions in such scenarios. LaBCAM finds that only uncertain remote retrieval engages canonical fear circuitry while regular retrieval does not. Longitudinal imaging of dendritic spines in RSc, a region involved in detection and context-dependent conflict resolution, reveals differential reorganization of spines during acquisition and rapid systems consolidation of HOA. Interestingly, we find HOA is implicated early in AD mice model (APP/PS1) and also in aged animals.

neuroscience↗

bioRxiv2026

Isolation of oxygen-dependent nicotine- and pseudooxynicotine-metabolizing enzymes

NicA2 is a flavin-bound amine dehydrogenase from Pseudomonas putida S16 that converts nicotine to the pharmacologically inactive N-methylmyosmine. In animal models of nicotine addiction, injection of NicA2 can decrease nicotine-seeking behavior 10-fold. Accordingly, NicA2-related enzymes have been investigated as smoking-cessation therapeutics. However, efficient catalysis by NicA2 in Pseudomonas putida relies on electron transfer to CycN, a cytochrome c, and not directly to O2. Impractically high amounts of NicA2 are thus necessary to achieve a pharmacological effect in the absence of CycN. Directed evolution has improved the ambient-O2 value of kcat from 0.007 s-1 to 1 s-1 for NicA2, but further improvements have been challenging. Here, we identify a strain of Peribacillus frigoritolerans NIC8 which encodes two flavin amine oxidoreductases, Ncox and Pnox. In the presence of oxygen, Ncox and Pnox act on nicotine and pseudooxynicotine respectively with apparent kcat values of 7.7 s-1 and 3.9 s-1. Transient kinetics establishes bimolecular rate constants of 51100 M-1s-1 and 81000 M-1s-1 for the half-reactions between Ncox and O2 and between Pnox and O2 respectively, consistent with Ncox and Pnox being bona-fide oxidases. Transcriptomics shows enhanced expression of Ncox and Pnox under nicotine-dependent growth as well as supporting the identification of downstream enzymes. Phylogenetic analysis suggests that Ncox and Pnox arose out of repurposing of homologous enzymes found in Bacillus species. The enzymes we describe may be useful for the development of nicotine addiction therapeutics and for bioconversion of nicotine in waste streams.

biochemistry↗

bioRxiv2026

B Cell Receptor Signaling Sets Boundaries for Selection of Broadly Neutralizing Antibody Functional Mutations

B cell signaling is required for germinal center (GC) selection and synergizes with T cell-help leading to differentiation into effector cells and a protective antibody response. Here, we studied the relationship between B cell signaling and the selection of functional mutations in a humanized mouse model of a CD4 binding-site specific HIV-1 broadly neutralizing antibody precursor. While BCR signaling increased with antigen affinity, immunization-induced frequency of a functional mutation was inversely related to affinity and favored a gain in association rate. Antigen-specific GC B cells and key mutation frequency were higher in the mid-affinity (0.5 - 5M) than in either the higher or lower affinity group, and were consistent with the significantly higher serum neutralization titers in the mid-range group. Our studies show that BCR signaling imposes boundaries (upper/lower) for selection of antibody functional mutations and support a "Goldilocks Zone" model that defines the favored BCR signaling strength for GC selection.

immunology↗

bioRxiv2026

Chromatin Landscape of Cancer Cell Lines Identifies Enhancer Subtypes

Epigenetic aberrations are a hallmark of cancer; however, systematic chromatin state maps of cancer cells are unavailable. We generated and analyzed 803 histone mark profiles in 142 cancer cell lines and 114 human tumors belonging to 9 solid tumor types. Irrespective of their cell-of-origin, cancer cells segregate from normal tissues based on their enhancer patterns, suggesting enhancer deregulation is a fundamental epigenetic feature in cancer. Enhancer based clustering defined 5 distinct subgroups of cancer cells (EpiC1-5) with unique developmental trajectories, molecular features and dependencies. Importantly, we define a set of core TFs that are critical for EpiC-specific enhancer patterns and survival. Notably, EpiC4 represented a predominantly epigenetic, pan-cancer subtype that displays poor survival, activation and dependence on a FN1-CAV1-SRC-PI3K-AKT signaling network. Together, these data uncover enhancer heterogeneity in pan-cancer systems with identification of a novel enhancer-based subtype and identify potential new therapeutic targets associated with unique epigenetic features.

cancer biology↗

bioRxiv2026

Scaling of Noise Under Resource Constraints in Gene Regulatory Motifs

Understanding noise propagation in gene regulatory circuits requires accounting for both model and resource constraints. In this work, we investigated the role of model order in influencing stochastic behaviour by deriving and analytically comparing reduced protein-only models with higher-order models that include mRNA and molecular complexes, and found that protein-based models can exhibit higher noise levels in the gene expression. Through frequency-response analysis, we explained that the higher-order models provide additional noise-filtering effects. We also analyzed a one-dimensional constrained model and showed that the Fano factor decreases as the strength of resource constraint increases. Finally, we considered larger circuit motifs, such as toggle switches and incoherent feed-forward loops, and found that resource limitations can minimise stochastic switching in a bistable circuit, whereas in an incoherent feed-forward loop, resource constraints can make the adaptation faster. Our results highlight that both mechanistic detail and shared resource constraints play a central role in determining fluctuation levels in biomolecular circuits.

systems biology↗

bioRxiv2026

Competing Molecular Interactions Govern the Dynamical Arrest of G3BP1 Condensates

G3BP1 is a central scaffold of stress granules (SGs). Upon cellular stress, G3BP1 forms complex coacervates with translationally repressed mRNAs and recruits multiple RNA-binding proteins to form reversible biomolecular condensates. Persistent SGs are linked to age-dependent dynamical arrest and impaired disassembly. Here, we employ active and passive nanoscale rheology with optical tweezers to show that G3BP1 condensates evolve from being dominantly viscous fluids to dynamically arrested network glasses characterized by nanoscale caging and elastic memory. Integrating atomistic and coarse-grained simulations with experiments, we find that electrostatic interactions between the oppositely charged intrinsically disordered regions drive condensate ageing. RNA modulates these interactions in a length-and structure-dependent manner, delaying dynamic arrest, whereas Caprin-1 binding to the NTF2L domain has little effect. Together, these findings reveal how competing inter-IDR and IDR-RNA interactions govern condensate ageing and material-state transitions. The findings have broader implications for the regulation of SG dynamics in cells.

biophysics↗

bioRxiv2026

Modulation of noisy gene expression by general sequestration mechanisms

Sequestration of gene products through diverse mechanisms forms a fundamental layer of regulation in intracellular biochemical processes, including post-translational modification, promiscuous binding to genomic decoy sites, and partitioning into membraneless compartments formed through phase separation. Here, we develop a unified stochastic framework to quantify how such sequestration-type processes, when coupled to noisy gene expression, modulate cell-to-cell variation in protein levels. In this model, protein molecules reversibly switch between active (free) and inactive (sequestered) states, whose switching rates are arbitrary functions of the molecular counts. Using exact analytical calculations and the linear noise approximation, we derive expressions for the Fano factor of the active-protein level and identify fluctuation attenuation regimes in terms of the logarithmic sensitivities of the switching rates to protein abundances. We show that inactive-protein-dependent switching, of which genomic decoy binding is a natural example, can preserve Poisson-level fluctuations in the active-protein level under appropriate conditions. Enzymatic inactivation, a type of post-translational modification, emerges as a special case of active-protein-dependent sequestration, where greater responsiveness of the inactivation propensity attenuates active-protein fluctuations. In both decoy binding and enzymatic inactivation, protecting the inactive protein from decay lowers active-protein fluctuations. Finally, a noise-buffering regime associated with intracellular phase separation is recovered when the inactive-to-active switching rate depends inversely on the inactive-protein level. Together, the examples of genomic decoy binding, enzymatic inactivation, and intracellular phase separation suggest that noise buffering observed across diverse intracellular processes is rooted in a broader class of reversible sequestration mechanisms that attenuate protein-level fluctuations.

systems biology↗

bioRxiv2026

Muon Reduces the Training Cost of Regulatory DNA Transformers

Gene-therapy design depends on identifying regulatory sequences that drive the right level, timing, and cell-type specificity of expression. Regulatory DNA models offer a way to prioritize such sequences computationally before committing candidates to biological testing. Biological validation involves DNA synthesis, cloning, cell culture, sequencing, and functional screening, so training compute is part of the same constrained discovery pipeline rather than an isolated modeling expense. Reducing the compute required to reach a target pretraining quality could shift time and budget toward larger candidate screens, additional assays, more cell contexts, and broader follow-up validation. Given that Adam-style optimizers are widely used for training genomic sequence models, we study whether Muon can provide a more compute-efficient alternative for regulatory DNA pretraining. We provide an in-depth analysis by training Transformer models (26M-420M parameters) on ENCODE cis-regulatory sequences with Adam and Muon while holding architecture, data, and non-optimizer hyperparameters fixed and varying optimizer family, norm-control scheme, learning rate, and model width. In the largest-scale matched-target comparison, Muon reaches Adam-matched perplexity targets with a median FLOP reduction of 35.4% and a median wall-clock time reduction of 38.5%. The analysis further shows that optimizer rankings depend on norm control: independent weight decay pairs more favorably with Muon than Hyperball in this setting. These findings indicate that optimizer update structure and norm-control choices are practical levers for reducing the training resources required to reach matched perplexity targets in regulatory DNA pretraining.

genomics↗

bioRxiv2026

Solid-state NMR Reveals Mobility-Based Organisation of the Schizosaccharomyces pombe Cell Wall

Fungal cell walls are hierarchically organised polysaccharide networks whose mechanical and functional properties depend on both chemical composition and molecular organisation. Although glucan synthases are essential for cell wall biosynthesis, how individual synthases shape the supramolecular architecture and dynamics of intact walls remains poorly understood. Here, we combine mobility-resolved 13C solid-state NMR spectroscopy with targeted genetic perturbation of the glucan synthases Ags1, Bgs1, and Bgs4 to determine how synthase activity governs the molecular organisation of the Schizosaccharomyces pombe cell wall. We first establish a molecular level reference for the wild-type wall by identifying the major glucan and mannan environments and resolving polysaccharides according to their mobility directly in intact cells. The rigid wall scaffold is dominated by unbranched {beta}-1,3-glucan and -1,3-glucan, whereas branched glucans and mannans occupy more dynamic molecular environments. Comparison with thermosensitive glucan synthase mutants reveals distinct, mutation-dependent reorganisation of both the rigid structural scaffold and the mobile polysaccharide matrix. Quantitative analysis further shows that, despite retaining broadly similar glucan compositions, the Ags1, Bgs1, and Bgs4 mutants redistribute carbohydrates among rigid, intermediate, and mobile molecular environments in distinct ways. These mutation-specific mobility fingerprints demonstrate that glucan synthases regulate not only polysaccha-ride biosynthesis but also how cell wall polymers are assembled, packed, and dynamically organised within the intact wall. More broadly, our findings establish molecular mobility as a sensitive signature of cell wall architecture that reveals structural consequences of biosynthetic perturbation not apparent from composition alone. Mobility-resolved solid-state NMR therefore provides a powerful framework for linking genetic perturbations to molecular dynamics and supramolecular organisation in intact fungal cell walls.

biophysics↗

bioRxiv2026

Quorum sensing underlies the establishment and maintenance of marginal zone B cells

The marginal zone (MZ) of the spleen harbors B cells that play an indispensable role in immune defense, orchestrating rapid responses to bloodborne pathogens. Under steady-state conditions, MZ B cell numbers are maintained through the balance of de novo generation from precursors, proliferative self-renewal, and loss. The mechanisms governing this homeostatic control remain elusive. Further, the developmental pathways underlying the establishment and continued supplementation of the MZ B cell compartment are not fullyelucidated. To address these gaps, we combined multiple fate-mapping tools and mathematical models to study MZ B cell dynamics in mice across the life course. Our analyses find evidence of quorum sensing mechanisms that regulate both the accumulation of mature MZ B cells during early life and their maintenance throughout adulthood. Specifically, we demonstrate that they derive predominantly from transitional B cell precursors with an efficiency that increases with age, reaching stable levels only in adulthood. MZ B cells compensate for this early developmental inefficiency through cell density-dependent proliferation, ensuring the timely establishment of a stable pool. Collectively, these findings unveil critical roles of quorum sensing and immune system maturation in the maintenance of this vital B cell subset.

immunology↗

bioRxiv2026

Lytic bacteriophages against Salmonella Typhi as a potential alternative to antibiotics

IntroductionEnteric fever, being endemic with seasonal peaks in low- and middle-income countries, is a major health concern. Moreover, the rise in antibiotic resistance has exacerbated the situation. This study was undertaken to investigate the lytic bacteriophages against Salmonella Typhi with a potential for phage therapy. Materials and MethodsA hospital-based cross-sectional study was conducted from October 2023 to March 2024. Blood cultures were processed by the BACTEC automated culture system following standard microbiological techniques to isolate typhoidal Salmonella. Antibiotic susceptibility was tested by the modified Kirby-Bauer disc diffusion method. Lytic bacteriophages isolated by the double-layer agar method were assessed for their host range and lytic ability with spot and turbidimetric assays. ResultsOf the total 1054 blood specimens, 35 (3.2%) were positive for S. Typhi. All the isolates were susceptible to first-line antibiotics--ampicillin, chloramphenicol, and cotrimoxazole. The isolates were also sensitive to nalidixic acid (80%) as well as fluoroquinolones; ciprofloxacin (62.86%), levofloxacin (77.14%), and ofloxacin (80%). Fifteen lytic phages were isolated against S. Typhi Ty2 and CT18 strains. Four phages--vB_SaTy_ST2, vB_SaTy_ST7, vB_SaTy_ST17, and vB_SaTy_ST18--lysed all 35 clinical S. Typhi isolates. While vB_SaTy_ST17 and vB_SaTy_ST18 also lysed 7 out of 20 S. Paratyphi A isolates. Three phages (vB_SaTy_ST2, vB_SaTy_ST7, vB_SaTy_ST17) were tested against S. Typhi isolate S30. Individually, vB_SaTy_ST17 suppressed the growth for 13 hours, vB_SaTy_ST2 and vB_SaTy_ST7 for 10 hours. The phage cocktail vB_SaTy_ST2 + vB_SaTy_ST17 was the most effective, which extended the inhibition time to 15 hours. ConclusionThis study highlights the ongoing burden of enteric fever in Nepal and the increase in susceptibility of S. Typhi to nalidixic acid and fluoroquinolones. It also demonstrates the promising lytic potential of bacteriophages, particularly vB_SaTy_ST17 and the phage cocktail vB_SaTy_ST2 + vB_SaTy_ST17, against clinical S. Typhi, highlighting their potential as alternatives to antibiotics.

microbiology↗