Overproduction of the pro-apoptotic molecule, programmed cell death 5, in Toxoplasma gondii leads to increased apoptosis of host macrophages.

We established a recombinant strain of Toxoplasma gondii that overexpressed programmed cell death 5 (TgPDCD5), in order to evaluate the role of endogenous TgPDCD5 in macrophage apoptosis during T. gondii infection. Immunofluorescence microscopy revealed that overproduced TgPDCD5 with a hemagglutinin tag was localized in the cytosol, which was consistent with the localization of endogenous TgPDCD5. The induced TgPDCD5-HA was recognized as an additional band by Western blot analysis, indicating successful overexpression of TgPDCD5. Secretion and release of TgPDCD5 by the parasite was also up-regulated in a time-dependent manner, which reflected its overproduction. Apoptosis due to parasite infection and interferon-gamma treatment was significantly up-regulated by the overexpression of TgPDCD5. These results suggest that endogenous TgPDCD5 plays a role in macrophage apoptosis during T. gondii infection.