AUTHOR=Xu Xiao-Pei , Elsheikha Hany M. , Liu Wen-Ge , Zhang Zhi-Wei , Sun Li-Xiu , Liang Qin-Li , Song Ming-Xin , Zhu Xing-Quan 

TITLE=The Role of Type II Fatty Acid Synthesis Enzymes FabZ, ODSCI, and ODSCII in the Pathogenesis of Toxoplasma gondii Infection

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.703059

DOI=10.3389/fmicb.2021.703059

ISSN=1664-302X

ABSTRACT=<p><italic>Toxoplasma gondii</italic> is an obligate intracellular protozoan parasite, which has a worldwide distribution and can infect a large number of warm-blooded animals and humans. <italic>T. gondii</italic> must colonize and proliferate inside the host cells in order to maintain its own survival by securing essential nutrients for the development of the newly generated tachyzoites. The type II fatty acid biosynthesis pathway (FASII) in the apicoplast is essential for the growth and survival of <italic>T. gondii</italic>. We investigated whether deletion of genes in the FASII pathway influences the <italic>in vitro</italic> growth and <italic>in vivo</italic> virulence of <italic>T. gondii</italic>. We focused on beta-hydroxyacyl-acyl carrier protein dehydratase (FabZ) and oxidoreductase, short chain dehydrogenase/reductase family proteins ODSCI and ODSCII. We constructed <italic>T. gondii</italic> strains deficient in <italic>FabZ, ODSCI</italic>, and <italic>ODSCII</italic> using CRISPR-Cas9 gene editing technology. The results of immunofluorescence assay, plaque assay, proliferation assay and egress assay showed that in RHΔ<italic>FabZ</italic> strain the apicoplast was partly lost and the growth ability of the parasite <italic>in vitro</italic> was significantly inhibited, while for RHΔ<italic>ODSCI</italic> and RHΔ<italic>ODSCII</italic> mutant strains no similar changes were detected. RHΔ<italic>FabZ</italic> exhibited reduced virulence for mice compared with RHΔ<italic>ODSCI</italic> and RHΔ<italic>ODSCII</italic>, as shown by the improved survival rate. Deletion of <italic>FabZ</italic> in the PRU strain significantly decreased the brain cyst burden in mice compared with PRUΔ<italic>ODSCI</italic> and PRUΔ<italic>ODSCII</italic>. Collectively, these findings suggest that FabZ contributes to the growth and virulence of <italic>T. gondii</italic>, while ODSCI and ODSCII do not contribute to these traits.</p>