Vaccination with Toxoplasma lysate antigen and CpG oligodeoxynucleotides: comparison of immune responses in intranasal versus intramuscular administrations

Parasitol Res. 2014 Jun;113(6):2277-84. doi: 10.1007/s00436-014-3882-0. Epub 2014 Apr 13.

Abstract

Toxoplasma gondii (T. gondii) is one of the most successful intracellular protozoan parasites on earth and highly prevalent in most warm-blooded vertebrates. There are no drugs that target the chronic cyst stage of this infection; therefore, development of an effective vaccine would be an important advance in disease control. Oligodeoxynucleotides (ODN) which contain immunostimulatory CG motifs (CpG ODN) can promote T-helper 1 (Th1) responses, an adjuvant activity that is desirable for vaccination against intracellular pathogen. In this study, we compare the immune responses of Toxoplasma susceptible C57BL/6 mice following intranasal and intramuscular vaccination with Toxoplasma lysate antigen (TLA) with or without CpG ODN as adjuvant. Immunized and control non-immunized mice were challenged with 85 cyst of the moderately virulent Beverley strain of T. gondii. Intranasal vaccination gave significantly a higher protection compared to other groups as indicated by prolonged survival and significantly reduced brain cyst burden (P < 0.01). Intranasal vaccination stimulated cellular immunity towards Th1 response characterized by significant INF-γ production (P < 0.01). Furthermore, fecal IgA antibody levels as an indicator of mucosal immune responses were significantly higher (P < 0.05) in intranasal vaccinated group before the challenge compared to all other groups. Intranasal vaccination was not able to upgrade the Th1 humoral arm. In contrast, intramuscular vaccination enhanced humoral immunity towards a type Th1 pattern characterized by a significant increase of specific IgG and Ig2a. Our results suggest that intranasal administration of CpG/TLA would provide a stable, pronounced, and effective vaccine against toxoplasmosis through stimulation of Th1 cellular immunity and mucosal IgA.

MeSH terms

  • Adjuvants, Immunologic / administration & dosage
  • Administration, Intranasal
  • Animals
  • Antigens, Protozoan / immunology*
  • Immunity, Cellular / immunology
  • Immunity, Mucosal
  • Immunoglobulin A
  • Injections, Intramuscular
  • Mice
  • Mice, Inbred C57BL
  • Oligodeoxyribonucleotides / immunology*
  • Protozoan Vaccines / administration & dosage
  • Protozoan Vaccines / immunology*
  • Toxoplasma / metabolism*
  • Toxoplasmosis / immunology
  • Toxoplasmosis / prevention & control*
  • Vaccination

Substances

  • Adjuvants, Immunologic
  • Antigens, Protozoan
  • CPG-oligonucleotide
  • Immunoglobulin A
  • Oligodeoxyribonucleotides
  • Protozoan Vaccines