Poster Presentation International Veterinary Immunology Symposium 2016

Evaluation of protective effect of pVAX-TgROP7 plasmid against acute and chronic toxoplasmosis in mice (#175)

Dong-Hui Zhou 1 , Yang Zhou 1 , Zi-Guo Yuan 2 , Di Ren 1 , Jia Chen 1 , Xing-Quan Zhu 1
  1. Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
  2. College of Veterinary Medicine, South China Agricultural University, Guangzhou, China

Background: Toxoplasma gondii can cause congential infection and abortion in humans and other warm-blooded animals. T. gondii rhoptry protein 7 (TgROP7) plays a critical role in parasite viability, and also is an important virulence factor of T. gondii. To evaluate the vaccine potential of TgROP7, a novel eukaryotic plasmid pVAX-ROP7 expressing TgROP7 from T. gondii RH strain was constructed and its expression and immunogenicity were demonstrated in vitro in the Marc145 cell by indirect immunofluorescence assay (IFA). Then, we evaluated the immune responses induced by DNA immunization with pVAX-ROP7 using a lymphoproliferative assay, cytokine and antibody measurements, and determination of the survival times of mice challenged with the virulent T. gondii RH strain (Type I) and the cyst-forming PRU strain (Type II) in brain.

Results: DNA immunization with pVAX-ROP7 induced significant specific humoral responses with high levels IgG and Th1-based cellular responses associated with the high levels of IFN-γ and IL-2 compared with all the controls (blank control, PBS, and pVAX). Also, pVAX-ROP7 immunization significantly prolonged survival time (13.5 ± 6.9 days) and reduced in brain cysts (55.64%) in contrast to control mice.

Conclusions: Our data suggested that pVAX-ROP7 could be used as a DNA vaccine candidate against toxoplasmosis, providing foundation for further development of effective vaccines against acute and chronic infection with T. gondii.