AUTHOR=Zheng Bin , Ding Jianzu , Lou Di , Tong Qunbo , Zhuo Xunhui , Ding Haojie , Kong Qingming , Lu Shaohong TITLE=The Virulence-Related MYR1 Protein of Toxoplasma gondii as a Novel DNA Vaccine Against Toxoplasmosis in Mice JOURNAL=Frontiers in Microbiology VOLUME=10 YEAR=2019 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00734 DOI=10.3389/fmicb.2019.00734 ISSN=1664-302X ABSTRACT=

Toxoplasma gondii causes serious public health problems, but there is no effective treatment strategy against it currently. DNA vaccines have shown promising findings in this regard. MYR1 is a new virulence factor identified in T. gondii that may have potential as a DNA vaccine candidate. We constructed a recombinant eukaryotic plasmid, pVAX1-MYR1, as a DNA vaccine, injected it intramuscularly into BALB/c mice, and evaluated its immunoprotective effects. pVAX1-MYR1 immunization induced a sequential Th1 and Th2 T-cell response, as indicated by high levels of Th1 and mixed Th1/Th2 cytokines at 2 and 6 weeks after immunization, respectively. These findings were corroborated by the antibody assays too. In addition, increased levels of antigen-specific lymphocyte proliferation, CD4+ and CD8+ T lymphocytes, cytotoxic T lymphocyte activity and cytokine (IFN-γ, IL-12, and IL-10) production were also observed in the immunized mice. These findings showed that pVAX1-MYR1 stimulated humoral and cellular immune responses in the immunized mice. The increased production of IFN-γ and IL-12 was correlated with increased expression of the T-bet and p65 genes of the NF-κB pathway. However, no significant increase was observed in the level of IL-4. The survival of mice immunized with pVAX1-MYR1 was also significantly prolonged compared with the control group mice. Based on all the above findings, the current study proposes that pVAX1-MYR1 can induce a T. gondii-specific immune response and should therefore be considered as a promising vaccine candidate against toxoplasmosis. To the best of our knowledge, this is the first report to evaluate the immunoprotective value of an MYR1-based DNA vaccine against T. gondii.