en Immune responses, deficiencies and vaccine candidates Immune responses, deficiencies and vaccine candidates Original article Original article <strong>Introduction: </strong>This study aimed to evaluate rSAG1-PLGA efficacy as a particulate vaccine in conferring protection against <em>Toxoplasma gondii</em> infection in C57BL/6 mice. In light of our previous studies, we studied mice genotype role in eliciting immune responses by rSAG1-PLGA nanoparticles in this study. <strong>Methods: </strong>Poly (DL-lactide-co-glycolide) (PLGA) nanoparticles loaded by rSAG1 as a subunit vaccine were prepared, and C57BL/6 mice were subcutaneously immunized twice at a 3-week interval by rSAG1-PLGA, soluble rSAG1, blank PLGA, and one group kept unvaccinated. The characteristics of PLGA nanoparticles, the amounts of produced IFN-&gamma;, IL-10, specific anti-<em>Toxoplasma</em>IgGs, and the conferred protection against infection by <em>T. gondii</em> RH tachyzoite were assessed. <strong>Results: </strong>rSAG1-PLGA nanoparticles shared a z-average of about 450nm with negative Zeta potential. Compared with the negative control group, the mice vaccinated with rSAG1-PLGA nanoparticles produced significantly higher amounts of IFN-&gamma;, specific anti-<em>T. gondii </em>IgG antibodies and higher titer of IgG2a, which resulted in longer survival times.<strong> Conclusion:</strong> The efficiency of rSAG1-PLGA nanoparticles in inducing humoral and cellular responses and consequently partial protection against acute toxoplasmosis in C57BL/6 was confirmed. : rSAG1-PLGA, Toxoplasma gondii, vaccine, C57BL/6, nanoparticles 38 45 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-322-1&slc_lang=en&sid=1 Mojgan Allahyari mojalah@yahoo.com 0000-0002-7370-9315 Yes Recombinant Protein Production Department, Production and Research Complex, Pasteur Institute of Iran, Karaj, Iran. Samira amiri samiraamiri.86@gmail.com 0000-0001-9753-5738 No Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran Alireza Vatanara vatanara@sina.tums.ac.ir 0000-0002-4293-8633 No Department of Pharmaceutics, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. Majid Golkar majid.golkar@gmail.com 0000-0002-0052-2410 No Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran.