Korean J Parasitol.  2018 Aug;56(4):325-334. 10.3347/kjp.2018.56.4.325.

Evaluation of Protective Immune Response Induced by a DNA Vaccine Encoding GRA8 against Acute Toxoplasmosis in a Murine Model

Affiliations
  • 1Stem Cell Research and Cellular Therapy Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong 524001, China.
  • 2Department of Gastroenterology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong 524001, China. quanjuanhua@gdmu.edu.cn
  • 3Department of Obstetrics and Gynecology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong 524001, China.
  • 4Institute of Immunology, Taishan Medical College, Tai’an, Shandong 271000, China.
  • 5Department of Infection Biology and Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea. yhalee@cnu.ac.kr

Abstract

Toxoplasma gondii is an apicomplexan zoonotic protozoan parasite that infects most species of warm-blooded animals, including humans. The heavy incidence and severe or lethal damage caused by T. gondii infection clearly indicate a need for the development of an effective vaccine. T. gondii GRA8 is a member of the dense granules protein family and is used as a marker of acute infection. In the present study, we evaluated the protective immunity induced by DNA vaccination based on a recombinant eukaryotic plasmid, pDsRed2-GRA8, against acute toxoplasmosis in mice. BALB/c mice were intramuscularly immunized with the pDsRed2-GRA8 plasmid and then challenged by infection with the highly virulent GFP-RH strain of T. gondii. The specific immune responses and protective efficacy against T. gondii of this vaccine were analyzed by measuring cytokine and serum antibody titers, splenocyte proliferation assays, and the survival times of mice after challenge. Our results showed that mice immunized with pDsRed2-GRA8 demonstrated specific humoral and cellular responses, induced higher IgG antibody titers with predominant IgG2a production; increased levels of IL-10, IL-12 (p70), IFN-γ, TNF-α, and splenocyte proliferation; and prolonged survival times compared to those of control mice. The present study showed that DNA immunization with pDsRed2-GRA8 induced humoral and cellular immune responses, and all immunized mice showed greater Th1-type immune responses and longer survival times than those of control mice. These results indicated that T. gondii GRA8 DNA immunization induces a partial protective effect against acute toxoplasmosis.

Keyword

Toxoplasma gondii; DNA vaccine; GRA8; immune response

MeSH Terms

Animals
DNA*
Humans
Immunity, Cellular
Immunization
Immunoglobulin G
Incidence
Interleukin-10
Interleukin-12
Mice
Parasites
Plasmids
Toxoplasma
Toxoplasmosis*
Vaccination
DNA
Immunoglobulin G
Interleukin-10
Interleukin-12
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