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

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

doi:10.3389/fmicb.2023.1302512

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

Front Microbiol. 2023 Nov 23:14:1302512. doi: 10.3389/fmicb.2023.1302512. eCollection 2023.

Authors

Xiao-Jing Wu^{1

2}, Jin Gao^{1

2}, Xiao-Nan Zheng¹, Hany M Elsheikha³, Ting-Ting Li², Yong-Jie Kou^{1

2}, Meng Wang², Xing-Quan Zhu¹

Affiliations

¹ Laboratory of Parasitic Diseases, College of Veterinary Medicine, Shanxi Agricultural University, Taigu, Shanxi Province, China.
² State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, China.
³ Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom.

Abstract

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 T. gondii remains largely unexplored. Here, we investigated the role of splicing factor SR2, a homolog of Plasmodium falciparum SR1, in the pathogenicity of T. gondii. We functionally characterized the predicted SR2 in T. gondii 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. In vitro 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 (p > 0.05). Interestingly, the disruption of SR2 in RH type I (p < 0.0001) and Pru type II (p < 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% (p < 0.0001). Collectively, these results suggest that splicing factor SR2 is important for the pathogenicity of T. gondii, providing a new target for the control and treatment of toxoplasmosis.

Keywords: CRISPR-Cas9; SR proteins; Toxoplasma gondii; alternative splicing; pathogenicity; splicing factor SR2.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by Shanxi Provincial Agricultural and Rural Research Program (grant no. LXXMsxnd202101), Shanxi Provincial Key Research and Development Program (grant no. 2022ZDYF126), the National Natural Science Foundation of China (grant nos. 32002306, 32172887), the Research Fund of Shanxi Province for Introduced High-level Leading Talents (grant no. RFSXIHLT202101) and the Special Research Fund of Shanxi Agricultural University for High-level Talents (grant no. 2021XG001). The funders had no role in the study design, data analysis, data interpretation, and the writing of this report.