Toxoplasma gondii is a widely distributed intracellular parasite that disrupts host immune and metabolic homeostasis. Although accumulating evidence highlights the role of gut microbiota in parasitic infections, the effects of acute T. gondii infection on host gut microbial ecology remain poorly understood. In this study, metagenomic sequencing technology was used to systematically analyze the composition and functional alterations of the ileal microbiota in BALB/c mice on day 10 post-infection. Compared to uninfected controls, T. gondii infected mice exhibited a significant reduction in microbial diversity and a pronounced shift in community structure. Notably, there was an expansion of Proteobacteria, particularly the Enterobacteriaceae family, alongside a marked decline in beneficial taxa such as Actinobacteria and Bacillota. Functional annotation using the KEGG and CAZy databases revealed enrichment of metabolic pathways related to glycolysis/gluconeogenesis, O-antigen nucleotide sugar biosynthesis, bacterial secretion systems, and biofilm formation-Escherichia coli in the infected microbiota. These findings provide novel insights into the dysbiosis of gut microbiota and host-microbe interactions during acute T. gondii infection.

Toxoplasma gondii is an obligate intracellular protozoan that infects humans and other mammals. The C57BL/6J mouse strain is regarded as an ideal model organism for studying T. gondii due to its susceptibility to T. gondii infection and its other advantages over other laboratory animals. However, systematic studies on the response dynamics of the susceptible C57BL/6J mice after oral infection with T. gondii cysts are lacking. To address this research gap, we investigated the spatiotemporal dynamics of infection, colonization, and antibody fluctuations in susceptible C57BL/6J mice orally infected with Type II T. gondii ME49 strain cysts. Mice were orally challenged with T. gondii cysts to examine the infection dynamics. Daily monitoring was conducted for 60 days post-infection (dpi) to assess animals’ clinical signs and survival rates. The parasite burden in various organs was quantified using qPCR targeting the T. gondii B1 gene. The serum antibody responses were evaluated using ELISA. The cyst burden in the mouse brain was assessed via histology and immunofluorescence. T. gondii infection induced clinical symptoms in the mice, including fever and weight loss. T. gondii rapidly invaded the mice’s small intestine, spleen, lungs, liver, and heart via the bloodstream within 1–5 dpi. T. gondii had breached the blood–brain barrier and colonized the brain by 7 dpi. The levels of Toxoplasma-specific IgG antibodies increased and stabilized for two months (until the experiment ended). Systemic parasite dissemination occurred rapidly, infiltrating most tissues and organs, leading to pronounced enteritis and multi-organ damage due to inflammation. The tachyzoites differentiated into bradyzoites when T. gondii infection progressed from the acute to the chronic phase in mice, forming tissue cysts in organs, including the muscles and brain. As a result, the predilection site of T. gondii in mice is the brain, which is where the cysts persisted for the host’s lifetime and continuously induced meningitis. These findings provide valuable insights into the spatiotemporal diffusion, colonization, predilection sites, temporal antibody dynamics, pathogen detection methodologies, and histopathological changes in C57BL/6J mice following oral infection with T. gondii cysts. These insights are important for elucidating T. gondii’s pathogenesis and host–T. gondii interaction.

Background: While Toxoplasma gondii infection poses a significant health threat, its impact on the localized intestinal lipid metabolism remains unclear. Methods: Thus, this study established an acute infection model in BALB/cJ mice and analyzed the colonic contents collected 10 days post-infection via untargeted lipidomics. The lipid profiles of the two groups diverged substantially, with a clear separation evident between infection and control conditions. Results: We identified 65 upregulated and 87 downregulated differential lipids, primarily falling into the glycerophospholipids and sphingolipids categories. Pathway enrichment analysis revealed that the choline metabolism in cancer and glycerophospholipid metabolism pathways was pinpointed as being among the most perturbed following infection. Correlation and network analyses further suggested that key molecules, such as LPC (20:4) and LPA (18:0), may mediate these metabolic pathway abnormalities by regulating related enzymatic activities. Conclusions: This systematic characterization of the intestinal lipid metabolic landscape in mice during acute T. gondii infection revealed the host intestinal lipid metabolic reprogramming induced by T. gondii infection. The findings offer a novel metabolic perspective for understanding T. gondii pathogenesis and host–parasite interactions.

Oxidative stress is a major consequence of environmental, metabolic, and disease-related challenges in poultry and can compromise cellular integrity and function. Although antioxidant defense mechanisms are broadly conserved across vertebrates, oxidative-stress responses in avian cells remain less well characterized than those in mammalian systems. Superoxide dismutase 1 (SOD1) is a key antioxidant enzyme, but how elevated SOD1 expression influences both oxidative injury and stress-responsive transcription in chicken cells remains incompletely understood. In this study, we established a stable SOD1-overexpressing chicken DF-1 fibroblast cell line and induced acute oxidative stress using hydrogen peroxide (H₂O₂). Cellular responses were evaluated using CCK-8 viability assays and Hoechst 33342/propidium iodide staining, followed by RNA sequencing and transcriptomic analyses. SOD1 overexpression markedly improved cell viability under H₂O₂ challenge and substantially reduced necrotic cell death, whereas its effect on apoptosis-associated changes was comparatively limited. Transcriptomic profiling showed that H₂O₂ induced extensive transcriptional reprogramming, while SOD1 overexpression reshaped this response by attenuating a subset of stress-inducible gene programs. Trend clustering further identified an H₂O₂-responsive module associated mainly with basic amino acid transport and stress-related regulatory processes that was less strongly induced in SOD1-overexpressing cells. Collectively, these findings demonstrate that elevated SOD1 expression enhances resistance to acute oxidative injury and modifies stress-responsive transcription in chicken fibroblasts. This study extends our current understanding of SOD1-mediated antioxidant cytoprotection in an avian cellular model and provides a molecular basis for further investigation of oxidative-stress regulation in poultry.

Background: Although Toxoplasma gondii has been recognized as an obligate intracellular parasite, the lipid metabolic alterations it induces in colonic contents during acute infection remain poorly characterized. Methods: An acute infection model was established using C57BL/6J mice by oral inoculation with the T. gondii ME49 strain. Untargeted lipidomics analysis was performed on the colonic contents collected at day 10 post-infection. Results: Acute infection significantly elevated glycerophospholipids (GPs) and reduced glycerolipids (GLs), and prenol lipids (PRs), leading to 136 differentially abundant lipids. Pathway enrichment analysis identified the two most significantly affected pathways: choline metabolism in cancer and glycerophospholipid metabolism, with lysophosphatidic acid (LPA(16:0)) and lysophosphatidylcholine (LPC(18:1)) functioning as core hub nodes. Receiver operating characteristic (ROC) analysis identified phosphatidylethanolamine (PE(20:1e_22:4)), PE(16:0_22:6), hexosylceramide (Hex1Cer(m18:0_20:4)), and Hex1Cer(t17:0_22:6) as exploratory candidate biomarkers with high discriminatory performance (AUC > 0.94). Conclusions: Acute T. gondii infection induces lipid metabolic reprogramming in colonic contents of C57BL/6J mice. The findings provide a novel metabolic perspective on the intestinal pathogenesis of toxoplasmosis and offer exploratory candidate lipid markers for diagnosing acute infection.