Immunization of C57BL/6 Mice with GRA2 Combined with MPL Conferred Partial Immune Protection against Toxoplasma gondii

Authors
Jalal Babaie 1
Samira Amiri 1
Robab Homayoun 1
Ebrahim Azimi 1
Reyhaneh Mohabati 1
Mahboubeh Berizi 1
M. Reza Sadaie 2
Majid Golkar 1
1 Molecular Parasitology Lab., Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
2 NovoMed Consulting, Silver Spring, Maryland, USA
10.22034/ibj.22.1.22
Abstract
BBackground: We have previously reported that immunization with GRA 2 antigen of Toxoplasma gondii induces protective immunity in CBA /J (H2k) and BALB/c mice (H2d). We aimed to examine whether immunization of a distinct strain of rodent with recombinant dense granule antigens (GRA2) combined with monophosphorryl lipid A (MPL) adjuvant elicits protective immune response against T. gondii. Methods: C57BL/6 (H2b haplotype) mice were immunized with GRA 2, formulated in MPL adjuvant. Results: Strong humoral response, predominantly of IgG1 subclass and cellular response, IFN-γ, was detected at three weeks post immunization. Mice immunized with GRA 2 had significantly (p < 0.01) fewer brain cysts than those in the adjuvant group, upon challenge infection. Despite the production of a strong antibody response, IFN-γ production and brain cyst reduction were not significant when the immunized mice were infected four months after the immunization. Conclusions: We can conclude that GRA2 immunization partially protects against T. gondii infection in C57BL/6 mice, though the potency and longevity of this antigen as a standalone vaccine may vary in distinct genetic backgrounds. This observation further emphasizes the utility of GRA 2 for incorporation into a multi-antigenic vaccine against T. gondii.
Keywords
Immunization
GRA2
Toxoplasma
MPL