Activation of chronic toxoplasmosis by transportation stress in a mouse model

// Bang Shen 1 , Yuan Yuan 1 , Jianxi Cheng 1 , Ming Pan 1 , Ningbo Xia 1 , Weichao Zhang 1 , Yifan Wang 1 , Yanqin Zhou 1 , Junlong Zhao 1, 2 1 State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China 2 Hubei Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, Hubei, PR China Correspondence to: Junlong Zhao, email: zhaojunlong@mail.hzau.edu.cn Keywords: Toxoplasma gondii, chronic infection, bradyzoite, reactivation, transportation stress Received: September 28, 2016 Accepted: November 02, 2016 Published: November 24, 2016 ABSTRACT Toxoplasma gondii is an obligate intracellular parasite infecting 25% of the world population and enormous number of animals. It can exist in two forms in intermediate hosts: the fast replicating tachyzoites responsible for acute infection and the slowly replicating bradyzoites responsible for life-long chronic infection. The interconversion between tachyzoites and bradyzoites plays critical roles in the transmission and pathogenesis of T. gondii . However, the molecular mechanisms that govern the interconversion are largely unknown. In this study, we established a chronic infection model in mice and examined the impact of transportation stress on the status of chronic infection. Our results demonstrated that, treating chronically infected mice with conditions mimicking transportation stress reduced the levels of several key cytokines that restrict the infection at chronic stage. Increased expression of the tachyzoite specific gene SAG1 (surface antigen 1) was detected in brain cysts of stress treated mice, indicating activation and conversion of bradyzoites to tachyzoites. Using this model, we identified fifteen toxoplasmic proteins that had significant abundance changes during stress induced cysts reactivation. These proteins serve as a basis for further investigation of the mechanisms governing bradyzoite conversion.