Biology subjects

Ganta, S.

Publications and source records attributed to Ganta, S..

5 recordsLinked to original sources

bioRxiv2026

Targeted mutagenesis in Ehrlichia canis deleting the phage head-to-tail connector protein gene and its assessment as a vaccine candidate preventing canine ehrlichiosis

Ehrlichia canis is primarily a Rhipicephalus sanguineus tick-borne rickettsial pathogen initially identified as causing canine monocytic ehrlichiosis, and infections in people have also been reported in Venezuela, Mexico, and parts of Europe. It is of high importance to have a vaccine suitable in protecting the canine host, which will aid in lessening E. canis infections also in people. Gene inactivation mutations in the phage head-to-tail connector protein genes (phtcp) from E. chaffeensis and A. marginale caused attenuated growth, and prior infection with the mutated bacteria induced protective immunity against wild-type bacterial infections in natural hosts, independent of blood-borne infection or tick-transmission infection. In the current study, we describe the development of targeted mutagenesis for the first time in E. canis genome and with a novel modification to avoid introducing antibiotic resistance cassettes to delete the phtcp ortholog from E. canis. The mutated E. canis was then assessed for its in vivo growth and the induction of host immunity exerted following the mutant infection aiding to protect against wild-type infection challenge in the canine host. We assessed systemic pathogen loads, hematological parameters, IgG immune responses, and plasma cytokines following the mutant infection relative to uninfected dogs. Similarly, the assessments were carried out following wild-type pathogen infections in dogs with or without prior mutant infection challenges. The study demonstrates that prior infection of dogs with the mutant induces immunity to prevent infection establishment by wild-type E. canis. Similarly, the mutant infection resulted in clear biological differences compared to the wild-type infection. This study establishes that the molecular genetic methods are broadly applicable to pathogens belonging to the family Anaplasmataceae and that the modified live vaccines with phtcp gene orthologs are valuable in reducing the diseases caused by the tick-borne rickettsial pathogens belong to Anaplasmataceae, including E. canis.

microbiology↗

bioRxiv2025

Region-specific human brain organoids reveal synaptic and cell state drivers of glioblastoma invasion

Glioblastoma (GBM) is a highly heterogenous and malignant brain tumor, in part because it disrupts normal brain circuits to fuel its own growth and invasion. Thus, there is a need to identify the molecular features of invasive GBM cells and their regulators in the neural microenvironment. To address this in a fully human model, we engrafted patient-derived GBM cells (total n=15 independent samples) from three sources-- fresh neurosurgical resections, cell lines, and whole GBM organoids--into human induced pluripotent stem cell-derived organoids patterned to forebrain, midbrain, and spinal cord identities. GBM cells from all sources infiltrated brain organoids within 2 days post-engraftment, reaching maximal invasion by day 14. Across organoids of distinct spatial and maturational milieu, GBM cells showed a consistent reduction in astrocyte-like states and an enrichment in neuron/glia progenitor-like (NPC-like) states. These NPC-like GBM cells expressed neuronal and synaptic machinery, and tumors enriched in this transcriptomic state prior to engraftment achieved greater organoid coverage, suggesting enhanced infiltration and synaptic integration of this GBM cell type. Although GBM cell states converged across organoid types after engraftment, infiltration was greater in the forebrain than spinal cord. This is likely reflective of synaptic input from deep-layer TBR1 excitatory neurons in the forebrain, as demonstrated by a combination of rabies-based monosynaptic tracing and single-cell transcriptomics. In contrast, inhibitory neurons were the predominant synaptic partners of GBM in the spinal cord. Together, this fully human model of the neural-GBM connectome reveals how neuron-like GBM states and regionally distinct synaptic inputs cooperatively shape tumor invasion.

neuroscience↗

bioRxiv2025

Identification and Characterization of Outer Membrane Proteins and Membrane Spanning Protein Complexes in Brucella melitensis

Brucellosis (Malta fever) is a zoonotic disease that affects both humans and animals, including cattle, sheep, and goats. Brucella melitensis is the most virulent and clinically significant species in humans. It is a Gram-negative bacterium with three groups of outer membrane proteins (OMPs): minor OMPs (Group 1), and major OMPs (Groups 2 and 3). OMPs with {beta}-barrel architecture play important roles in nutrient transport, efflux, adhesion, and membrane biogenesis. Despite their importance, the structure, function, and interaction dynamics of several B. melitensis {beta}-barrel OMPs and associated protein complexes remain mostly unexplored. In this study, we conducted a comprehensive in silico analysis to characterize known outer membrane {beta}-barrel (OMBB) proteins and identify novel OMBBs in B. melitensis 16M. Proteins were modelled using five computational tools: AlphaFold 3, ESMFold, SWISS-MODEL, RoseTTAFold, and TrRosetta. Outer-membrane insertion of the novel OMBBs was confirmed using PPM 3.0, Protein GRAVY, DREAMM, and MemProtMD_Insane. Putative functions were predicted using structure- and sequence-based annotations. Sequence variation across 46 B. melitensis strains were identified and mapped onto the structural models. OMBB-associated protein complexes - the RND (Resistance-Nodulation-Division) efflux pumps, the lipopolysaccharide transport (Lpt) complex, and the {beta}-barrel assembly machinery (BAM) complex - were modelled, and protein-protein interactions (PPIs) were analyzed to confirm thermodynamically stable assemblies. This study presents a robust in silico strategy for exploring OMP architecture and provides valuable structural insights to support the development of diagnostics, targeted therapeutics, and vaccines against B. melitensis.

bioinformatics↗

bioRxiv2025

Design of a Multi-Epitope Vaccine using β-barrel Outer Membrane Proteins Identified in Chlamydia trachomatis

Chlamydia trachomatis is an obligate intracellular Gram-negative pathogen responsible for causing sexually transmitted infections (STIs) and trachoma. Current interventions, including screening and antibiotics, are limited due to the widespread nature of asymptomatic infections, and the absence of licensed vaccine exacerbates the challenge. In this study, we predicted outer membrane {beta}-barrel (OMBB) proteins and designed a multi-epitope vaccine (MEV) construct using identified proteins. We employed a consensus-based computational framework on the C. trachomatis D/UW-3/CX proteome and identified 17 OMBB proteins, including well-known Pmp family members and MOMP. Eight OMBB proteins were computationally characterized, which showed significant structural homology with known outer membrane proteins from other bacteria. Sequence-based annotation tools were used to determine their putative functions. B-cell and T-cell epitopes were predicted from the selected proteins. The MEV construct was designed using four cytotoxic T lymphocyte (CTL) epitopes and 29 helper T lymphocyte (HTL) epitopes predicted from six OMBB proteins, which were conserved across 106 C. trachomatis serovars. The vaccine was supplemented at the N-terminus with Cholera enterotoxin subunit B and PADRE sequence to enhance its immunogenicity. The MEV construct of 780 amino acids was antigenic, non-allergenic, non-toxic, and soluble. Secondary structure analysis revealed 95% random coils. The 3D structural model of MEV was generated and validated, confirming its structural reliability. Molecular docking between MEV and Toll-like receptor 4 (TLR4) revealed strong and stable binding interactions, supporting its potential to elicit a strong immune response. This study highlights OMBB proteins as promising immunogenic targets and presents a computationally designed MEV candidate for C. trachomatis infection.

bioinformatics↗

bioRxiv2022

Quisinostat is a brain-penetrant radiosensitizer in glioblastoma

In recent years, histone deacetylase inhibitors (HDACi) have garnered considerable interest for the treatment of adult and pediatric malignant brain tumors. However, owing to their broad-spectrum nature and inability to effectively penetrate the blood-brain barrier, HDACi have failed to provide significant clinical benefit to glioblastoma (GBM) patients to date. Moreover, global inhibition of HDACs results in widespread toxicity, highlighting the need for selective isoform targeting. While no isoform-specific HDACi are currently available, the second-generation hydroxamic acid-based HDACi quisinostat possesses sub-nanomolar specificity for class I HDAC isoforms, particularly HDAC1 and 2. Recently, we demonstrated that HDAC1 is the essential HDAC in GBM. Here, we provide the first report on the neuro-pharmacokinetic, pharmacodynamic and radiation-sensitizing properties of quisinostat in preclinical models of GBM. We demonstrate that quisinostat is a well-tolerated and brain-penetrant molecule that significantly extends survival when administered in combination with radiation in vivo. The pharmacokinetic-pharmacodynamic-efficacy relationship was established by correlating free drug concentrations and evidence of target modulation in the brain with survival benefit. Together, these data provide a strong rationale for clinical development of quisinostat as a radiosensitizer for the treatment of GBM.

cancer biology↗