Antigenic Epitope Analysis and Efficacy Evaluation of GRA41 DNA Vaccine Against T. gondii Infection.

Abstract

Toxoplasma gondii has a comprehensive impact on a great range of warm-blood mammals, in which one-third of the population all over the world is involved. Dense granular proteins, regarded as GRA family, mediating substantial interface between host cell cytoplasm and parasite, are widely studied for preventing the infection of T. gondii. As is handled in our study, the effect of intramuscularly injecting the genetic vaccine pEGFP-C1/GRA41 encoding a novel dense granule protein, GRA41, was evaluated. At the beginning, bioinformatics analysis was used to evaluate epitopes of both B cells and T cells on the GRA41 protein of T. gondii. Afterwards, recombinant plasmids (pEGFP-C1/GRA41) were injected into BALB/c mice and the quantity of IgG and its subclass IgG2a remarkably increased. IFN-γ, distinctive from the other cytokines (IL-4, and IL-10), was significant in growth. Afterwards, the intraperitoneal challenge was executed for recording survival time with tachyzoites with high virulence (in RH strain) and counting the number of brain cysts was carried out after the infection of PRU strain (low virulence). In pEGFP-C1/GRA41 group, the survival period was significantly longer (13.3 ± 3.37 days) after tachyzoites attack with the RH strain in high virulence, compared with the other groups (less than 8 days). Additionally, the cyst quantity is remarkably lower and the rate of reduction could reach 59.34%. All the results indicated effective protection of DNA vaccine encoding GRA41 against T. gondii.