Small GTPase Immunity-Associated Proteins Mediate Resistance to Toxoplasma gondii Infection in Lewis Rat.

Rats vary in their susceptibilities to infection depending on the rat strain. Compared to the -susceptible Brown Norway (BN) rat, the Lewis (LEW) rat is extremely resistant to Thus, these two rat strains are ideal models for elucidating host mechanisms that are important for host resistance to infection. Therefore, in our efforts to unravel molecular factors directing the protective early innate immune response in the LEW rat, we performed RNA sequencing analysis of the LEW versus BN rat with or without infection. We identified three candidate small TPase munity-ssociated roteins (GIMAPs) that were upregulated (false discovery rate, 0.05) in the LEW rat in response to infection. Subsequently, we engineered -susceptible NR8383 rat macrophage cells for overexpression of LEW rat-derived candidate GIMAP 4, 5, and 6. By immunofluorescence analysis we observed that GIMAP 4, 5, and 6 in -infected NR8383 cells each colocalized with GRA5, a parasite parasitophorous vacuole membrane (PVM) marker protein, suggesting their translocation to the PVM. Interestingly, overexpression of each candidate GIMAP in -infected NR8383 cells induced translocation of LAMP1, a lysosome marker protein, to the surface membrane. Importantly, overexpression of GIMAP 4, 5, or 6 individually inhibited intracellular growth, with GIMAP 4 having the highest inhibitory effect. Together, our findings indicate that upregulation of GIMAP 4, 5, and 6 contributes to the robust refractoriness of the LEW rat to through induction of lysosomal fusion to the otherwise nonfusogenic PVM.