Biology subjects

Dsouza, L.

Publications and source records attributed to Dsouza, L..

7 recordsLinked to original sources

bioRxiv2026

The Hidden Cost of Blue Light: Multiorgan Pathology Induced by LED Exposure in Mice

Life evolved under broad-spectrum sunlight (300-3500 nm), but most modern light-emitting diodes (LEDs) emit within a restricted visible range (350-650 nm) leaving lighting environments that are short-wavelength dominant. We ask if chronic 450nm exposure dominant in LEDs alters metabolism and organ integrity in ageing mice environmentally exposed at 13 mW/cm{superscript 2} for 5 h/day over 40 weeks, at an intensity within the range of human environmental exposures. Mice exhibited progressive weight gain despite reduced food intake, with altered glucose tolerance and insulin sensitivity over time. White adipose tissue mass increased, while brown adipose tissue weight and UCP1 protein levels remained unchanged. Relative organ weights (heart, liver, kidney, testis) were each reduced by ~10%, with histopathology revealing fat deposition, hepatocellular degeneration, renal tubular damage, steatosis, and impaired testicular architecture. These findings demonstrate that chronic 450 nm light exposure is associated with metabolic alterations and multiorgan pathology in mice.

pathology↗

bioRxiv2026

A Course-Undergraduate Research Experience (CURE) to explore the effect of structural variants on gene expression in C. elegans balancers

Bioinformatics, a discipline at the crossroads of Biology and Computational Sciences, also referred to as Computational Biology, is nowadays widely spread in research programs. However, implementing any Bioinformatics projects requires the ability to comprehend biological concepts and apply computational approaches, and rare are the undergraduate programs offering such multi-disciplinary training. In addition, understanding the dynamic between Biology research projects and Bioinformatics analyses is challenging with no real-life experience. Course-based undergraduate research experience (CURE) courses are innovative programs that allow more students to acquire research experience and provide the perfect setting to introduce students to applied bioinformatics. As a part of the Bachelor of Health Sciences of the Cumming School of Medicine at the University of Calgary (Canada), a CURE applied bioinformatics was implemented in the Winter of 2023 to 2025. Students investigated the effect of structural variants (SVs, genetic variants larger than 50 bp) on gene expression in the model organism Caenorhabditis elegans (a hermaphrodite 1-mm long roundworm). The students detected and characterized SVs by analyzing genome and transcriptome sequencing data of C. elegans strains called balancers, as they are known to carry large genomic variations balancing regions of the genome by limiting recombination and allowing maintenance of lethal mutations. They used Galaxy, a public web-based supercomputing resource, but also a local High-Performance computing system, and R, to report different effects of SVs on gene expression and splicing. Students research explained the molecular mechanism behind the uncoordinated phenotype caused by the reciprocal translocation eT1(III;V) and uncovered unexpected effects on gene expression on an understudied gene. We evaluated the courses impact on student learning journeys and showed that the CURE favored students understanding of the Bioinformatics field and fostered their research interest. We provide here guidelines to facilitate the CURE implementations to improve access for undergraduate students to bioinformatics research experiences.

bioinformatics↗

bioRxiv2025

Discovery and Characterization of a Hydroxypyridone-3-carboxamide Analog as an Antiviral Lead against Orthopoxviruses

Orthopoxviruses remain a persistent global health concern due to the ongoing circulation of mpox, the possibility of the re-emergence of smallpox, and the threats posed by many poxviruses that infect animals and/or humans. The limited availability of antiviral drugs, the unproven efficacy in humans, and the emergence of resistant mutants underscore the need for new and better therapeutics. In this study, we identify and characterize ZW-2038, a hydroxypyridone-3-carboxamide analog, as an antiviral compound against vaccinia virus (VACV), monkeypox virus (MPXV), and cowpox virus (CPXV). Discovered through a focused in-house small-molecule screen, ZW-2038 exhibited low micromolar potency and high selectivity in primary human fibroblasts. The compound also reduced viral replication under physiomimetic conditions including human and monkey intestinal organoids (enteroids) and ex vivo mouse lung tissue models. Mechanistically, ZW-2038 suppresses VACV DNA replication and downstream post-replicative gene expression, albeit without inhibiting MPXV resolvase (Mpr) in vitro. These findings, along with in vitro safety profiling and mice pharmacokinetics studies, characterize ZW-2038 as a promising yet suboptimal antiviral lead against orthopoxviruses warranting future development.

microbiology↗

bioRxiv2025

Ciclopirox suppresses poxvirus replication by targeting iron metabolism

Poxviruses remain a significant global health concern, necessitating the development of novel antiviral strategies. Through high-throughput screening, we previously identified ciclopirox (CPX), an FDA-approved antifungal, as a hit that inhibits vaccinia virus (VACV) replication. Here, we further characterized its antiviral activity and mechanism of action using human primary fibroblasts. CPX significantly reduced VACV titers without reducing host cell viability, with an EC50 in the sub-micromolar range and a CC50 >500 M. Rescue experiments demonstrated that CPX inhibits viral replication primarily through chelation of intracellular Fe3+ and, to a lesser extent, Fe2+, as evidenced by partial restoration of viral replication with ferric ammonium citrate supplementation. Furthermore, overexpression of the iron-dependent enzymes RRM2 and the VACV-encoded F4L reduced the inhibitory effect of CPX, indicating that these host and viral proteins are affected by CPX treatment. Moreover, CPX treatment also suppressed cowpox virus and monkeypox (mpox) virus replication in vitro. It also reduced VACV titers in ex vivo mouse lung tissue. These findings highlight host iron metabolism as a critical determinant of poxvirus replication and support repurposing CPX as a broad-spectrum orthopoxvirus antiviral candidate.

microbiology↗

bioRxiv2024

Role of vaccinia virus growth factor in stimulating the mTORC1-CAD axis of the de novo pyrimidine pathway under different nutritional cues

Vaccinia virus (VACV), the prototype poxvirus, actively reprograms host cell metabolism upon infection. However, the nature and molecular mechanisms remain largely elusive. Given the diverse nutritional exposures of cells in different physiological contexts, it is essential to understand how VACV may alter various metabolic pathways in different nutritional conditions. In this study, we established the importance of de novo pyrimidine biosynthesis in VACV infection. We elucidated the significance of vaccinia growth factor (VGF), a viral early protein and a homolog of cellular epidermal growth factor, in enabling VACV to phosphorylate the key enzyme CAD of the de novo pyrimidine pathway at serine 1859, a site known to positively regulate CAD activity. While nutrient-poor conditions typically inhibit mTORC1 activation, VACV activates CAD via mTORC1-S6K1 signaling axis, in conditions where glutamine and asparagine are absent. However, unlike its cellular homolog, epidermal growth factor (EGF), VGF peptide alone in the absence of VACV infection has minimal ability to activate CAD, suggestive of the involvement of other viral factor(s) and differential functions to EGF acquired during poxvirus evolution. Our research provides a foundation for understanding the regulation of a significant metabolic pathway, namely, de novo pyrimidine synthesis during VACV infection, shedding new light on viral regulation under distinct nutritional environments. This study not only has the potential to contribute to the advancement of antiviral treatments but also improve the development of VACV as an oncolytic agent and vaccine vector. ImportanceOur research provides new insights into how VACV alters the mTORC1-CAD signaling axis under different nutritional cues. The identification of how VACV regulates a major enzyme, CAD, within the de novo pyrimidine synthesis pathway, establishes a molecular mechanism for determining how VACV reshapes this essential pathway, necessary for facilitating efficient VACV replication. We further emphasize that, despite nutrient-poor conditions, which typically inhibit mTORC1 activation, VACV can stimulate mTORC1. We identify its early growth factor, VGF, as an important factor for this stimulation of mTORC1 and its downstream effector CAD, revealing a new mechanism for how VACV sustains mTORC1-CAD axis activation under these nutrient deficient conditions. This work provides fresh insights into the molecular mechanisms of mTORC1-CAD regulation, which has the potential to be utilized to enhance VACV as an oncolytic tool, vaccine vector and aid in the development of antiviral drugs.

microbiology↗

bioRxiv2023

Upregulation of ATP Citrate Lyase Phosphorylation and Neutral Lipid Synthesis through Viral Growth Factor Signaling during Vaccinia Virus Infection

Like all other viruses, poxviruses rely on host cells to provide metabolites and energy. Vaccinia virus (VACV), the prototype poxvirus, induces profound metabolic alterations in host cells. We previously showed that VACV infection increases the tricarboxylic acid (TCA) cycle intermediates, including citrate, that can be transported to the cytosol to be converted to acetyl-CoA for de novo fatty acid biosynthesis. ATP citrate lyase (ACLY) is a pivotal enzyme converting citrate to acetyl-CoA. Here, we report that VACV infection stimulates the S455 phosphorylation of ACLY, a post-translational modification that stimulates ACLY activity. We demonstrate that the chemical and genetic inhibition of ACLY severely suppresses VACV replication. Remarkably, we found that virus growth factor (VGF)-induced signaling is essential for the VACV-mediated upregulation of ACLY phosphorylation. Furthermore, the upregulation of ACLY phosphorylation during VACV infection is dependent on the activation of the cellular Akt kinase that phosphorylates ACLY. Finally, we report that VGF-induced ACLY phosphorylation via the EGFR-Akt pathway is important for VACV stimulations of neutral lipid droplet synthesis. These findings identified a previously unknown way of rewiring cell metabolism by a virus and a novel function for VGF in the governance of virus-host interactions through the induction of a key enzyme at the crossroads of the TCA cycle and fatty acid de novo biosynthesis. Our study also provides a mechanism for the role played by VGF and its downstream signaling cascades in the modulation of lipid metabolism in VACV-infected cells. ImportanceATP citrate lyase is a key metabolic enzyme that sits at the crossroads of glucose, glutamine, and lipid metabolism. However, how virus infection affects this protein is unclear. Using chemical, genetic, and metabolic approaches we show that VACV, the prototype poxvirus, increases the phosphorylation of ACLY in primary human fibroblasts in a VGF-dependent manner. We further show that the VGF-EGFR-Akt signaling pathway is vital for VACV-induced lipid droplet synthesis. Our findings identified ACLY as a potential target for novel antiviral development against pathogenic poxviruses. Our study also expands the role of growth factor signaling in boosting VACV replication by targeting multiple metabolic pathways.

microbiology↗

bioRxiv2023

Antiviral activities of two nucleos(t)ide analogs against vaccinia and mpox viruses in primary human fibroblasts

Many poxviruses are significant human and animal pathogens, including viruses that cause smallpox and mpox. Identification of inhibitors of poxvirus replication is critical for drug development to manage poxvirus threats. Here we tested two compounds, nucleoside trifluridine and nucleotide adefovir dipivoxil, for antiviral activities against vaccinia virus (VACV) and mpox virus (MPXV) in physiologically relevant primary human fibroblasts. Both trifluridine and adefovir dipivoxil potently inhibited replication of VACV and MPXV (MA001 2022 isolate) in a plaque assay. Upon further characterization, they both conferred high potency in inhibiting VACV replication with half maximal effective concentrations (EC50) at low nanomolar levels in our recently developed assay based on a recombinant VACV secreted Gaussia luciferase. Our results further validated that the recombinant VACV with Gaussia luciferase secretion is a highly reliable, rapid, non-disruptive, and simple reporter tool for identification and chracterization of poxvirus inhibitors. Both compounds inhibited VACV DNA replication and downstream viral gene expression. Given that both compounds are FDA-approved drugs, and trifluridine is used to treat ocular vaccinia in medical practice due to its antiviral activity, our results suggest that it holds great promise to further test trifluridine and adefovir dipivoxil for countering poxvirus infection, including mpox.

microbiology↗