Elsevier

Available online 8 August 2020, 104441

Microbial Pathogenesis

Highlights

A DNA cocktail vaccine including TgSAG1 and TgROP2 was constructed.

HBsAg was used as an adjuvants to improve the immunity of cocktail vaccine.

PEGFP-N1-HBsAg-SAG1-ROP2 enhanced the T. gondii-specific humoral and cellular Th1 immune responses.

Mice immunized with vaccine showed significantly increased survival time.

Abstract

Toxoplasma gondii is an intracellular obligate parasitic protozoon that can infect all warm-blooded animals, causing zoonotic toxoplasmosis. So far, there is no commercial toxoplasmosis vaccine for human use. In the present study, we constructed a DNA vaccine cocktail which includes the surface protein (SAG1) and the rhoptry protein ROP2 denoted as pEGFP-N1-SAG1-ROP2. In order to improve the efficacy, HBsAg was used as a genetic adjuvant to construct pEGFP-N1-HBsAg-SAG1-ROP2. Two eukaryotic plasmids were transiently transfected into HEK293T cells and the expression was examined using fluorescence microscopy and western blotting. We then immunized Kunming mice intramuscularly with the DNA vaccine. After three immunizations, the immune response was evaluated by measuring antibody levels, cytokine production, percentages of CD4+ and CD8+ T lymphocytes, and the survival times of the T. gondii RH strain challenged mice. The results showed that the two DNA vaccines stimulated Th1 responses, and had a higher antibody titer, IL-2, IL-12, and IFN-γ levels, and percentage of CD4+ and CD8+ T lymphocytes than the control group. In addition, mice immunized with the pEGFP-N1-HBsAg-SAG1-ROP2 vaccine showed increased survival times compared with pEGFP-N1-SAG1-ROP2.

Keywords

Toxoplasma gondii

DNA vaccine

HBsAg genetic adjuvant

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© 2020 Published by Elsevier Ltd.



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