AUTHOR=Wu Xiao-Jing , Gao Jin , Zheng Xiao-Nan , Elsheikha Hany M. , Li Ting-Ting , Kou Yong-Jie , Wang Meng , Zhu Xing-Quan 

TITLE=The splicing factor SR2 is an important virulence factor of Toxoplasma gondii

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1302512

DOI=10.3389/fmicb.2023.1302512

ISSN=1664-302X

ABSTRACT=<p>Serine/arginine-rich (SR) proteins are key factors with important roles in constitutive and alternative splicing (AS) of pre-mRNAs. However, the role of SR splicing factors in the pathogenicity of <italic>T. gondii</italic> remains largely unexplored. Here, we investigated the role of splicing factor SR2, a homolog of <italic>Plasmodium falciparum</italic> SR1, in the pathogenicity of <italic>T. gondii</italic>. We functionally characterized the predicted SR2 in <italic>T. gondii</italic> by gene knockout and studied its subcellular localization by endogenous protein HA tagging using CRISPR-Cas9 gene editing. The results showed that SR2 was localized in the nucleus and expressed in the tachyzoite and bradyzoite stages. <italic>In vitro</italic> studies including plaque formation, invasion, intracellular replication, egress and bradyzoite differentiation assays showed that deletion of SR2 in type I RH strain and type II Pru strains had no significant effect on the parasite growth and bradyzoite differentiation (<italic>p</italic> &gt; 0.05). Interestingly, the disruption of SR2 in RH type I (<italic>p</italic> &lt; 0.0001) and Pru type II (<italic>p</italic> &lt; 0.05) strains resulted in varying degrees of attenuated virulence. In addition, disruption of SR2 in type II Pru strain significantly reduced brain cyst burden by ~80% (<italic>p</italic> &lt; 0.0001). Collectively, these results suggest that splicing factor SR2 is important for the pathogenicity of <italic>T. gondii</italic>, providing a new target for the control and treatment of toxoplasmosis.</p>