The guanylate binding proteins (GBPs) are a family of 65-73kDa IFN-inducible
GTPases, conserved among vertebrates, with several reported functions in intrinsic
immunity to intracellular pathogens. Murine GBPs (mGBP) and human GBPs
(hGBP) have been shown to contribute to IFNg-mediated immunity against the
apicomplexan parasite Toxoplasma gondii. In this thesis, I seek to expand our
knowledge of mGBP- and hGBP-mediated restriction of Toxoplasma gondii. To
elucidate new functions of mGBPs, I investigate novel potential interacting
partners. Specifically, a putative interaction between mGBP1 and the chromatin
modifying protein RNF20 is explored. In the context of hGBPs, I investigate four as
yet uncharacterised hGBPs; hGBP2, hGBP3, hGBP4 and hGBP5, in the context of
Toxoplasma gondii infection in a human epithelial cell. I generate, optimise and
characterise numerous tools to research these hGBPs localisation and function,
including CRISPR knockout cell lines, titratable overexpression systems and novel
high-throughput automated assays for phenotypic quantifications. Utilising these
tools, I determine that hGBPs 2-5 do not contribute to IFNg-mediated restriction of
Toxoplasma gondii in A549 epithelial cells and make an argument for these
observations being a specific phenomenon of non-phagocytic human cells.