Toxoplasma gondii and the study of host-parasite interactions

Intracellular pathogens are a major cause of mortality and morbidity in humans. Many intracellular pathogens secrete proteins that manipulate host cells to create the niche in which the pathogen can replicate. In turn, host cells have intricate mechanisms to detect and combat invading pathogens. As a consequence pathogens and their hosts co-evolve, leading to variation in both host and pathogen genomes and to the emergence of differences in parasite virulence and host resistance. Compared to bacteria and viruses, relatively little is known about how more complex eukaryotic pathogens co-evolve with and manipulate their hosts.

We are interested in susceptibility to infection which is likely caused by a complex interplay between host and parasite. We study host-parasite interactions between the obligate intracellular eukaryotic parasite Toxoplasma gondii and its hosts. Toxoplasma can infect virtually any cell and causes life-long chronic infections (toxoplasmosis) in most warm-blooded animals. It is estimated that 30% of humans are infected with Toxoplasma. Although most infected individuals are asymptomatic, Toxoplasma can cause severe disease in immunosuppressed individuals and fetuses and also causes ocular disease in otherwise healthy people. Toxoplasma virulence differs, often quite dramatically, depending on the infecting strain and the host. The focus of the Saeij laboratory over the last years has been to identify genes of Toxoplasma that modulate the host cell and/or determine virulence, host genes and pathways that determine resistance/susceptibility, and to characterize their specific interactions. To achieve this we use a combination of genetics, genomics, biochemistry, microscopy, immunology and computational tools.

For more information on what we do please visit our research pages

Toxoplasma gondii in the media

Latest News

[Jan, 2016] David Arranz Solis starts as a postdoctoral fellow in the Saeij lab, welcome David!

[Feb, 2016] Tatiana Paredes Santos starts as a postdoctoral fellow in the Saeij lab, welcome Tatiana!

[Jan, 2016] Shruthi Krishnamurthy starts as a postdoctoral fellow in the Saeij lab, welcome Shruthi!

[Jan, 2016] Lamba Sangare starts as a postdoctoral fellow in the Saeij lab, welcome Lamba!

[Nov, 2015] Debanjan Mukhopadhyay starts as a postdoctoral fellow in the Saeij lab, welcome Debanjan!

[Nov, 2015] Yifan Wang starts as a postdoctoral fellow in the Saeij lab, welcome Yifan!

[Oct, 2015] Kimberly Cirelli successfully defends her thesis, she will start as a postdoc in Shane Crotty's lab at the La Jolla Institute for Allergy and Immunology.

[Sep, 2015] The Saeij lab is now officially located at UC Davis

[June, 2015] Dan Gold and Kimberly Cirelli both won a best oral presentation award at the international toxoplasmosis meeting

[May, 2015] Kimberly Cirelli wins a AAI Trainee Poster Award

[May 2015] Dan Gold's paper describing the molecular basis for the pores in the Toxoplasma parasitophorous vacuole membrane that mediate the passive diffusion of small molecules into the vacuole is published in Cell Host & Microbe. Read an MIT news article describing this research.

[May, 2015] The NIH funds our R21 proposal to identify novel peptides that can be used to determine the exact strain people infected with Toxoplasma are infected with.

[Apr, 2015] The NIH funds our R01 renewal on characterizing the Toxoplasma proteins involved in the modulation of the host cell. We published 24 papers during the first five years of funding!

[Apr, 2015] The Saeij lab is looking for 4 new postdoctoral fellows. Go to Opportunities for information on how to apply.

[Apr, 2015] On September 1st, 2015, The Saeij lab is going to move to the Department of Pathology, Microbiology and Immunology at the School of Veterinary Medicine at the Univesity of California Davis. We are excited that we will now also be able to investigate the Toxoplasma sexual cycle in cats.

[Feb, 2015] Ana Camejo starts her new job as the editor for Trends in Parasitology.

[Feb, 2015] Kirk Jensen's and Ana Camejo's paper showing that Toxoplasma gondii Superinfection and Virulence during Secondary Infection Correlate with the Exact ROP5/ROP18 Allelic Combination is published in Mbio.

[Dec, 2014] The NIH funds our R21 on characterizing the Toxoplasma proteins involved in forming the pore in the parasitophorous vacuole membrane that mediates passive transport of small molecules.

[Nov, 2014] Musa Hassan's review on incorporating alternative splicing and mRNA editing into the genetic analysis of complex traits is published.

[Sep, 2014] Ninghan Yang successfully defends her thesis, she will continue her research career in Antonia Bertoletti's lab at the Duke-NUS Graduate Medical School.

[Sep, 2014] Kirk Jensen starts as an assistant professor in UC Merced

[May, 2014] Jeroen Saeij awarded tenure at MIT

[Sep, 2014] Musa Hassan continues his Wellcome trus-MIT fellowship in the lab of Prof. Markus Meissner at the Wellcome Trust Centre for Molecular Parasitology in Glasgow

[May, 2014] Microbiology graduate student Ben Waldman joins the Saeij lab

[Feb, 2014] Emily Rosowski's paper on the mechanisms by which Toxoplasma inhibits STAT1 activity published in Infection and Immunity. Read the paper

[Jan, 2014] Eleni Konstantinou starts as a research fellow in the Saeij lab

[Jan 6, 2014] Kimberly Cirelli's paper on the dual role for inflammasome sensors NLRP1 and NLRP3 in murine resistance to Toxoplasma gondii accepted in mBio. Read the paper

[Dec 22, 2013] Kimberly Cirelli's paper on the genetic basis for rat strain differences in macrophage pyroptosis upon Toxoplasma infection accepted in PLoS Pathogens.

[Dec 19, 2013] Mariane Melo's paper on transcriptome analysis of macrophages infected with 29 different Toxoplasma strains published in PLoS Pathogens. (Read the paper). *News Coverage: MIT news

[Dec, 2013] Wendy Niedelman's paper on the mechanism by which gamma interferon-stimulated human fibroblasts inhibit Toxoplasma growth published in Infection and Immunity. (Read the paper).

[Nov 29, 2013] Dan Lim's paper on the crystal structure of the ROP18 kinase published in The Journal of biological chemistry. (Read the paper).

[Nov 13, 2013] Musa Hassan's paper on the genetic basis for individual differences in RNA editing accepted in Genome Research.

[Sep, 2013] Ana Camejo's paper on the discovery of novel rhoptry proteins accepted in The International Journal for Parasitology.

[July 1o, 2013] Ninghan Yang's paper on the genetic basis for phenotypic differences between type I strains published in BMC Genomics. (Read the paper).

[June, 2013] Kirk Jensen's paper on the role of ROP16 and GRA15 on the modulation of intestinal inflammation published in Infection and Immunity. (Read the paper).

[June, 2013] Daniel Gold wins The “Elsevier Investigator Award for best talk” at the 12^th International Congress on toxoplasmosis at St. Catherine’s College, Oxford University in England.

[May 19, 2013] Jeroen Saeij gives the Division AA Lecture at the ASM 113th general meeting "Susceptibility to Infection: A Complex Interplay between Host and Parasite Genotypes". *News coverage: ASM Microbe Magazine.