Evaluation of Immunogenic Effect of Toxoplasma gondii RecombinantSAG-1 Antigen with Propranolol as Adjuvant in BALB/c Mice

Abstract

Purpose: Propranolol as a novel adjuvant, was used to evaluate the immunogenic effect of three doses of recombinant SAG-1 (rSAG-1) antigen of Toxoplasma gondii in BALB/c mice for finding the optimal dose, and was compared with efficacy of tachyzoite lysate antigen (TLA). Methods: Eight different groups of 15 BALB/c mice received different volumes of the immunogenic material (three doses of r SAG-1 and one dose of TLA antigens), with or without propranolol adjuvant, subcutaneously. The control group mice received only PBS. Three weeks after the last immunization, the serum levels of IgG2a, IgG1 and IgG total antibodies against TLA, splenic interleukin-5 (IL-5) and Interferon-gamma (IFN-γ) (produced against TLA) and the splenic lymphocyte proliferation after adding TLA were measured to evaluate humoral and cellular immune responses. Challenge test was performed by subcutaneously injection of 1000 alive and active tachyzoites in to five mice per each group and survival days for each group of mice were recorded. Results: The mice group that received propranolol adjuvant and 20 µg of r SAG-1 antigen per dose of injection showed significantly more IFN-γ production, more proliferation of splenic lymphocytes and higher anti-TLA-specific IgG2a production (three main indexes for cell mediated immunity) in comparison with other groups. Moreover, in the challenge test, this group of mice had a significantly increased survival time, indicating the positive effect of propranolol in the more stimulating of cellular immunity that is necessary for toxoplasmosis prevention or suppress. Conclusion: Our results showed that T. gondii rSAG-1 antigen in combination with propranolol as adjuvant (which can induce Th1 related responses) are good candidates for further study to a vaccine design.

Evaluation of Adjuvant Effectiveness of Alum-Propranolol Mixture on the Immunogenicity of Excreted/Secreted Antigens of Toxoplasma gondii RH Strain

“…In 2019, Abbasi et al performed a study on T. gondii SAG1 antigens in BALB/c mice, and their results indicated that PRP-receiving groups with SAG1 antigen increased IFN-γ production and elevated immune system shift to TH1. 35 By comparing the MTT assay and the survival rate of the mice, we found that these tests are high in the groups using alum-PRP and higher in the PRP-receiving groups. In Abbasi et al’s study, IL-5 levels were higher in the TLA-recipient group, whereas in our study, the group used alum with the antigen was the highest.…”

“…As already demonstrated, Th1 cells are responsible for cell-mediated immunity, whereas Th2 responses support humoral immunity. 35 Thus, the immunity induced by the administration of dual adjuvants with the ESA vaccine was biased toward cell-mediated rather than humoral immunity. Furthermore, alum-PRP mixture used as an adjuvant increased the proliferation of lymphocytes and improved resistance characterized by the prolonged survival time of mice challenged with T. gondii RH strain.…”

“…These differences are probably due to our use of alum and different antigens, which alum caused a shift in immunoreactivity and increased IL-5. 35 …”

Oral Immunization With a Plant HSP90-SAG1 Fusion Protein Produced in Tobacco Elicits Strong Immune Responses and Reduces Cyst Number and Clinical Signs of Toxoplasmosis in Mice

“…In general, an immune response that induces the production of IgG2a and/or IgG2b antibodies is mainly mediated by Th1 cells, whereas the production of IgG1 antibodies is mediated by Th2 cells (Snapper and Paul, 1987;Snapper et al, 1988;Stevens et al, 1988). Several reports showed that adjuvant-free recombinant SAG1 used in mouse immunizations does not enhance an effective humoral response against T. gondii infection or enhance a non-protective Th2 antibody response (Naeem et al, 2018;Abasi et al, 2019;Sánchez-López et al, 2019;Pagheh et al, 2020). In fact, SAG1 immunization was always analyzed with an adjuvant to generate a strong Th1 immune response (Wang and Yin, 2014).…”

Evaluation of In Vitro Cytotoxic and Apoptotic Effects of Miltefo-sine on the Toxoplasma gondii RH Strain

“…T he intracellular parasite, Toxoplasma gondii , is a cosmopolitan apicomplexan protosa important in human and veterinary medicines( 1 – 2 ). It is one of the most significant zoonotic feline gastrointestinal parasites transmitted to humans without the help of intermediate hosts or vectors ( 3 ).…”