DNA Vaccine Encoding the Chimeric Form of Schistosoma mansoni Sm-TSP2 and Sm29 Confers Partial Protection against Challenge Infection

PLoS One. 2015 May 5;10(5):e0125075. doi: 10.1371/journal.pone.0125075. eCollection 2015.

Abstract

Schistosomiasis is an important parasitic disease worldwide that affects more than 207 million people in 76 countries and causes approximately 250,000 deaths per year. The best long-term strategy to control schistosomiasis is through immunization combined with drug treatment. Due to the ability of DNA vaccines to generate humoral and cellular immune responses, such vaccines are considered a promising approach against schistosomiasis. Sm29 and tetraspanin-2 (Sm-TSP2) are two proteins that are located in the S. mansoni tegument of adult worms and schistosomula and induce high levels of protection through recombinant protein immunization. In this study, we transfected BHK-21 cells with plasmids encoding Sm29, Sm-TSP2 or a chimera containing both genes. Using RT-PCR analysis and western blot, we confirmed that the DNA vaccine constructs were transcribed and translated, respectively, in BHK-21 cells. After immunization of mice, we evaluated the reduction in worm burden. We observed worm burden reductions of 17-22%, 22%, 31-32% and 24-32% in animals immunized with the pUMVC3/Sm29, pUMVC3/SmTSP-2, pUMVC3/Chimera and pUMVC3/Sm29 + pUMVC3/SmTSP-2 plasmids, respectively. We evaluated the humoral response elicited by DNA vaccines, and animals immunized with pUMVC3/Sm29 and pUMVC3/Sm29 + pUMVC3/SmTSP-2 showed higher titers of anti-Sm29 antibodies. The cytokine profile produced by the spleen cells of immunized mice was then evaluated. We observed higher production of Th1 cytokines, such as TNF-α and IFN-γ, in vaccinated mice and no significant production of IL-4 and IL-5. The DNA vaccines tested in this study showed the ability to generate a protective immune response against schistosomiasis, probably through the production of Th1 cytokines. However, future strategies aiming to optimize the protective response induced by a chimeric DNA construct need to be developed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Helminth / immunology
  • Antigens, Helminth / genetics
  • Antigens, Helminth / immunology*
  • Cell Line
  • Cytokines / biosynthesis
  • Female
  • Gene Expression
  • Granuloma / parasitology
  • Granuloma / pathology
  • Helminth Proteins / genetics
  • Helminth Proteins / immunology*
  • Immunization
  • Immunoglobulin G / immunology
  • Mice
  • RNA, Messenger
  • Recombinant Proteins / immunology
  • Schistosoma mansoni / genetics
  • Schistosoma mansoni / immunology*
  • Schistosomiasis mansoni / prevention & control*
  • Spleen / immunology
  • Vaccines, DNA / immunology*

Substances

  • Antibodies, Helminth
  • Antigens, Helminth
  • Cytokines
  • Helminth Proteins
  • Immunoglobulin G
  • RNA, Messenger
  • Recombinant Proteins
  • Vaccines, DNA

Grants and funding

This work was supported by the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (SCO), Fundação de Amparo a Pesquisa do Estado de Minas Gerais (SCO), Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior (SCO), and Insituto Nacional de Ciencia e Tecnologia em Doenças Tropicais (SCO). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.