Biology subjects

Petrosova, H.

Publications and source records attributed to Petrosova, H..

5 recordsLinked to original sources

bioRxiv2026

Host adaptation drives genome evolution and virulence diversification in a bacterial zoonotic pathogen

Understanding how zoonotic pathogens diversify across reservoir hosts remains a central question in evolutionary biology and infectious disease research. Here, we address this challenge using Leptospira interrogans, a globally distributed bacterial pathogen with an extremely wide range of animal reservoirs, as a model. After defining 13 distinct genogroups that largely align with serogroups, we selected the strongly host-adapted rodent-associated lineage, which is more frequently associated with fatal outcomes in patients, and the cattle-associated lineage for further analysis. A comprehensive approach integrating multi-omics analyses and host-specific infection assays showed that these two genogroups have followed distinct evolutionary trajectories associated with host specialization. Genomics demonstrated that specialized genogroups are genetically less diverse, characterized by divergence in membrane and signaling genes, and by the acquisition of host-adaptive functions. Changes in gene expression and protein production revealed distinct regulatory programs, predominantly affecting virulence pathways in rodent-borne lineage and stress responses in cattle-borne lineage. Consistently, rodent-borne lineage causes greater disruption of human epithelial barrier integrity and elicits an attenuated host-dependent macrophage inflammatory response relative to cattle-borne lineage. Collectively, these findings reveal distinct host-adaptive strategies and remarkable evolutionary plasticity in a major zoonotic bacterium, highlighting the central role of intraspecies heterogeneity in shaping host specialization.

microbiology↗

bioRxiv2025

Methionine regulates antitumor function of CD8⁺ T cells through polyamine synthesis

Methionine is an essential amino acid critical for T cell activation. While methionine restriction (MR) combined with immune checkpoint blockade has been shown to enhance T cell function, the impact of methionine on adoptive T cell therapies is largely unexplored. Here, we examined the functionality of T cells under MR and pharmaceutical inhibition of the methionine cycle (MAT2Ai), using primary T cells and a murine adoptive T cell therapy model. In vitro, transient MR or MAT2Ai treatment increased interferon gamma (IFN{gamma}) expression in CD8+ T cells, whereas sustained MR led to the upregulation of T cell exhaustion-associated markers. Mechanistically, transient MR suppressed the polyamine synthesis pathway, and supplementation with polyamines reversed MR-induced IFN{gamma} expression. Genetic ablation of s-adenosylmethionine decarboxylase, an enzyme in the polyamine synthesis pathway, recapitulated the effect of MR, indicating that transient MR enhances T cell function by inhibiting polyamine synthesis. Despite this, transient MR treatment of ovalbumin (OVA)-specific (OT-I) CD8+ T cells prior to adoptive transfer did not improve antitumor efficacy against EG7-OVA tumors in vivo. In contrast, sustained dietary MR accelerated EG7-OVA tumor growth in mice treated with OT-I T cells, demonstrating that methionine availability is essential for the activity of adoptively transferred T cells. These findings suggest that enhancing methionine availability in the tumor microenvironment may improve the efficacy of adoptive T cell therapies.

immunology↗

bioRxiv2025

DMEM and EMEM are suitable surrogate media to mimic host environment and expand leptospiral pathogenesis studies using in vitro tools

Pathogenic Leptospira species can survive and thrive in a wide range of environments. Distinct environments expose the bacteria to different temperatures, osmolarities, and amounts and sources of nutrition. However, leptospires are mostly cultured, in a laboratory setting under in vitro conditions that do not reflect natural environments. This constraint on laboratory cultures limits the applicability of in vitro studies to the understanding of even simple pathogenic processes. Here we report, investigate, and identify a medium and conditions that mimic the host environment during leptospirosis infection, expanding the available in vitro tools to evaluate leptospiral pathogenesis. We quantified genome-wide gene expression of pathogenic Leptospira interrogans cultured in different in vitro media compositions (EMJH, DMEM, EMEM, and HAN). Using EMJH as standard, we compared gene expression in these compositions to genome-wide gene expression gathered in a host environment: whole blood (WB) of hamsters after infection with pathogenic leptospires. Leptospires cultured in DMEM and EMEM media shared 40% and 47% of all differentially expressed genes (DEGs) of leptospires present within WB (FDR<0.01), while leptospires cultured in HAN media only shared 20% of DEGs with those from WB. Furthermore, gene and pathway expression of leptospires cultured on DMEM and EMEM media exhibited a better correlation with leptospires grown in WB, including promoting expression of a similar leptospiral lipid A profile to the one identified directly in host tissues. Taken together, these results indicate that commercial cell-culture media EMEM or DMEM are better surrogates for in vivo pathogenic studies than EMJH or HAN media in Leptospira. These alternative culture conditions, using media that are a standard supply worldwide, provide a reproducible and cost-effective approach that can accelerate research investigation and reduce the number of animal infections necessary for basic research of leptospirosis.

microbiology↗

bioRxiv2024

Lipid A double bond position determination using ozone and laser-induced dissociation

Ozone coupled with tandem MS is a traditional tool to assign double bond position in lipids. However, few studies were reported on the use of ozone for double bond determination of bacterial lipids. Most MS-based double bond localization methods used in bacterial lipidomics focused on low molecular weight phospholipids, but never tested for assigning double bond position in complex glycolipids such as Lipid A. Here, we present a simple approach to identify unsaturated lipid A double bond position using on-MALDI plate ozone treatment of intact Lipid A.

microbiology↗

bioRxiv2023

Structural Elucidation of Intact Rough-Type Lipopolysaccharides using Field Asymmetric Ion Mobility Spectrometry and Kendrick Mass Defect Plots

Lipopolysaccharide (LPS) is a hallmark virulence factor of Gram-negative bacteria. It is a complex, structurally heterogeneous mixture due to variations in number, type, and position of its simplest units: fatty acids and monosaccharides. Thus, LPS structural characterization by traditional mass spectrometry (MS) methods is challenging. Here, we describe the benefits of field asymmetric ion mobility spectrometry (FAIMS) for analysis of intact R-type lipopolysaccharide complex mixture (lipooligosaccharide; LOS). Structural characterization was performed using Escherichia coli J5 (Rc mutant) LOS, a TLR4 agonist widely used in glycoconjugate vaccine research. FAIMS gas phase fractionation improved the (S/N) ratio and number of detected LOS species. Additionally, FAIMS allowed the separation of overlapping isobars facilitating their tandem MS characterization and unequivocal structural assignments. In addition to FAIMS gas phase fractionation benefits, extra sorting of the structurally related LOS molecules was further accomplished using Kendrick mass defect (KMD) plots. Notably, a custom KMD base unit of [Na-H] created a highly organized KMD plot that allowed identification of interesting and novel structural differences across the different LOS ion families; i.e., ions with different acylation degrees, oligosaccharides composition, and chemical modifications. Defining the composition of a single LOS ion by tandem MS along with the organized KMD plot structural network was sufficient to deduce the composition of 179 LOS species out of 321 species present in the mixture. The combination of FAIMS and KMD plots allowed in-depth characterization of the complex LOS mixture and uncovered a wealth of novel information about its structural variations.

biochemistry↗