Project description:Toxoplasma gondii is an apicomplexan parasite that approximately infects one third of the human population worldwide. When sporulated oocysts that are shed in the faeces of infected felids are accidentally ingested through contaminated food or water, sporozoites can infect the intestine of the intermediate host. Upon this infection, the fast replicating tachyzoites then disseminate overall the body and can cross the blood-brain, blood-retina or the blood-placenta barrier. Eventually, immune pressure will lead to differentiation into the slow replicating bradyzoites that are contained within tissue cysts for life. Despite the importance of sporulation for transmission, the process is not yet understood. We therefore exploited Illumina Next-Generation RNA-Sequencing to analyse the transcriptome of oocysts in the process of sporulation and compared it to unsporulated and sporulated oocysts. We thus identified genes that are highly specific to the sporulation process and that may be involved in the formation of sporozoites.
Project description:Recent advances in high throughput sequencing methodologies allow the opportunity to probe in depth the transcriptomes of organisms including N. caninum and Toxoplasma gondii. In this project, we are using Illumina sequencing technology to analyze the transcriptome (RNA-Seq) of experimentally accessible stages (e.g. tachyzoites at different times points) of T. gondii VEG strain. The aim is to make comparative transcriptional landscape maps of Neospora and Toxoplasma at different time points at different life cycle stages and compare levels of expression of orthologous genes in these two organisms.
Project description:To investigate transcriptional role of TgSNF2L on type II Toxoplasma gondii (ME49 Tir1), an auxin inducible degron system was introduced to control the protein expression of TgSNF2L after adding IAA.
Project description:Toxoplasma gondii is a ubiquitous protozoan with a complex life cycle involving transitions between different hosts and developmental stages, each adapted to a unique niche within its host. However, the regulatory mechanisms controlling these life cycle transitions remain poorly understood. In this study, we characterized the AP2 factor AP2X-1, which is expressed during the tachyzoite and bradyzoite stages, but not in the mature merozoite stage. Knockout of ap2X-1 significantly impaired tachyzoite invasion and replication, while increasing the frequency of bradyzoite differentiation. As a component of the HDAC3/MORC complex, knockout of ap2X-1 led to the upregulation of bradyzoite and sexual stage-specific genes. Single-cell sequencing revealed that ap2X-1 knockout strains behaved as a mixed population of tachyzoites, bradyzoites, merozoites, and sporozoites. CUT&Tag analysis revealed substantial overlap between AP2X-1 and HDAC3/MORC complex binding at the promoters of bradyzoite and sexual stage-specific genes. Additionally, ATAC-seq analysis demonstrated that AP2X-1 modulates chromatin compaction and accessibility, suggesting that AP2X-1 recruits the HDAC3/MORC complex to repress bradyzoite differentiation and sexual commitment. The loss of ap2X-1 resulted in significant attenuation of T. gondii virulence and reduced the formation of brain cysts in vivo. These findings identify AP2X-1 as a critical negative regulator of T. gondii sexual development.
Project description:Toxoplasma gondii is a ubiquitous protozoan pathogen able to infect both mammalian and avian hosts. Surprisingly, just three strains appear to account for the majority of isolates from Europe and N. America. To test the hypothesis that strain divergence might be driven by differences between mammalian and avian response to infection, we examine in vitro strain-dependent host responses in a representative avian host, the chicken. Chicken embryonic fibroblasts were cultivated in vitro and infected with different strains of Toxoplasma gondii (Type II = ME49, Type III = CEP); host transcriptional responses were then analyzed at 24 hours post-infection.