A Novel wx2 Gene of Toxoplasma gondii Inhibits the Parasitic Invasion and Proliferation in vitro and Attenuates Virulence in vivo via Immune Response Modulation.

Zhenrong Ma,Yehong Huang,Linfei Yang,Ruolan Jiang,Jie Guan,Xuanwu Li,Bin Lu,Jie Zhang,Xiang Wu,Kang Yan,Yunfeng Chang

doi:10.3389/fmicb.2020.00399

Abstract

Toxoplasma gondii (T. gondii) is an obligate intracellular apicomplexan protozoan that can parasitize most warm-blooded animals and cause severe diseases in immunocompromised individuals or fetal abnormalities in pregnant woman. The treatment of toxoplamosis has been limited by effective drugs. Our previous work indicated that the novel gene wx2 of T. gondii may serve as a vaccine antigen candidate. To further investigate the molecular functions of wx2 in highly virulent T. gondii (RH strain), a wx2 gene deletion mutant RH strain (KO-wx2) was established using CRISPR-Cas9. The phynotype of KO-wx2 was analyzed by plaque, invasion, and replication assays in vitro as well as in vivo virulence assays. The results indicated that the targeted deletion of the wx2 gene significantly inhibited in vitro parasite growth and replication in the host cells as well as attenuated parasite virulence in the mouse model. Notably, the percentage of pro-inflammatory factors of interferon gamma (IFN-γ) and interlukin-17A (IL-17A) and anti-inflammatory factor of interlukin-10 (IL-10) in the lymph nodes were upregulated in mice infected with the KO-wx2 strain. Our data suggested that the wx2 gene plays an important role in the process of the parasite’s life cycle and virulence in mice. In addition, it also plays an important role in the host’s immunity reaction, mainly via Th1 and Th17 cellular immunity, not Th2.

Highlights

As a member of the phylum apicomplexa, Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan capable of infecting a world-wide range of hosts, including most warm-blooded animals like humans and cats (Saad et al, 2018; Tang et al, 2019)
Our previous research has shown that WX2 was a membrane molecule and the wx2 gene was a dependable DNA vaccine candidate of T. gondii (Wu et al, 2007)
Gene ontology analysis of wx2 showed that the downregulated genes included GADD45A and DDIT3, and the upregulated genes included RAC1 and PPP3 (Supplementary Table 3)

Summary

Introduction

As a member of the phylum apicomplexa, Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan capable of infecting a world-wide range of hosts, including most warm-blooded animals like humans and cats (Saad et al, 2018; Tang et al, 2019). It is estimated that about one-third of the world’s human population has been infected with T. gondii. The infection is asymptomatic in the majority of cases, it can cause severe complications and even death in wx Gene Function of T.gondii immunocompromised individuals (Jiang et al, 2018). The Toxoplasma vaccine remains the main preventive measure (Jiang et al, 2018). There are no successful Toxoplasma vaccines that can be applied clinically. Much of current research currently focuses on identification of virulence factors and exploring potential Toxoplasma vaccine candidates. Micronemes, dense particles, and secretory proteins (ROPs, MICs, or GRAs, respectively) have been confirmed to be the main virulence molecules, there has been no considerable breakthrough in current research regarding new virulence factors

Methods

Results

Conclusion