Characterization of a new effector protein in Toxoplasma gondii

Description of projects available to graduate students:
Toxoplasma gondii is a globally ubiquitous parasite that infects nearly all warm blooded animals, from birds to humans. Nearly 20% of the world's population has been infected with this parasite, and it causes severe disease in the developing fetus and in immunocompromised patients. As on obligate intracellular pathogen, we are interested in identifying effector proteins that are secreted from the parasite into the host cell.

We have identified multiple loci in the T. gondii genome that are tandemly duplicated in this species, and many of them encode putative effectors that are secreted into the host cell. We hypothesize that these loci are responsible for expanded host range and pathogenesis of T. gondii, traits that distinguish this species from its closest extant relatives.

The rotation project will focus on characterizing one of these loci that encodes a novel dense granule protein that is secreted into the host cell. Since we only recently discovered this protein the student will attempt to determine where the protein traffics once in the host cell and the effects of deleting the locus on T. gondii host cell interactions.

The student will:
1. Use confocal microscopy with strains expressing epitope-tagged forms of the protein to identify its subcellular location(s) in the host cell.
2. Knock the gene out using double homologous recombination.
3. Determine if the knockout strains have altered growth rates in vitro.
4. Characterize the pathogenesis of knockout strains in mice using in vivo bioluminescence imaging.

These experiments will attempt to establish a role for this protein in T. gondii biology, and set the stage for future experiments using microarrays and other molecular and cell biology techniques to examine how this protein interacts with the host cell.

Techniques graduate student will learn:
Microarray analyses, cell culture, genetic engineering of parasites, immunofluorescence and confocal microscopy, standard PCR/cloning techniques