The Impact of the Antigenic Composition of Chimeric Proteins on Their Immunoprotective Activity against Chronic Toxoplasmosis in Mice

Abstract

Toxoplasmosis may pose a serious threat for individuals with weakened or undeveloped immune systems. However, to date, there is no specific immunoprophylaxis for humans. Thus, the aim of this study was to evaluate the immunogenicity of three trivalent—SAG2-GRA1-ROP1L (SGR), SAG1L-MIC1-MAG1 (SMM), and GRA1-GRA2-GRA6 (GGG)—and two tetravalent—SAG2-GRA1-ROP1-GRA2 (SGRG) and SAG1-MIC1-MAG1-GRA2 (SMMG)—chimeric T. gondii proteins, as well as their protective potential against chronic toxoplasmosis in laboratory mice. All three trivalent recombinant proteins possessed immunogenic properties, as defined by specific humoral and cellular responses in vaccinated mice characterized by the synthesis of specific IgG (IgG1/IgG2a) antibodies in vivo and the release of Th1/Th2 cytokines by stimulated splenocytes in vitro. Immunization with all three recombinant proteins provided partial protection against toxoplasmosis, although the protective capacity strongly depended on the individual antigenic composition of each preparation. The antigens providing the highest (86%) and lowest (45%) protection, SGR and SMM, respectively, were supplemented with GRA2 antigen fragment, to form the tetravalent chimeric proteins SGRG and SMMG. Further study revealed that the tetravalent preparations exhibited high immunogenic potential; however, the addition of another antigen to the recombinant protein structure had distinct effects on the protection generated, compared to that of the trivalent counterparts, depending on the antigen tested.

Immunoproteomic Approach of Extracellular Antigens From Paracoccidioides Species Reveals Exclusive B-Cell Epitopes

“…Thus, we identified several exclusive and conserved epitopes in the Paracoccidioides complex, since these molecules are candidates for the specific diagnosis of PCM. Similar analyses have already been performed in other works, where linear B-cell epitopes were employed for serological detection of several pathogenic organisms, such as Borrelia miyamotoiis (Tokarz et al, 2019), Toxoplasma gondii (Gatkowska et al, 2019), Treponema pallidum (Ogden et al, 2019), Leishmania spp. (Bremer Hinckel et al, 2019;Vale et al, 2019), and several human viruses (Amrun et al, 2019;Mutsvunguma et al, 2019;Yao et al, 2019).…”

Immunogenicity and Protective Effect of a Virus-Like Particle Containing the SAG1 Antigen of Toxoplasma gondii as a Potential Vaccine Candidate for Toxoplasmosis

“…Recently the subcellular organelles of T. gondii, such as dense granules (GRAs), the rhoptry, the microneme, and the inner membrane complex, have been used as major recombinant proteins and/or antigens for vaccine candidates, as well as major targets for inhibiting T. gondii infection. Furthermore, various studies regarding vaccine development have been reported, particularly vaccine researches against T. gondii infection [36][37][38][39][40], as well as the surface antigens and recombinant chimeric proteins of T. gondii [41][42][43][44]. Nevertheless, the recent studies have still difficulties in relation to parasite infection and its treatment.…”

The Immunogenic and Immunoprotective Activities of Recombinant Chimeric T. gondii Proteins Containing AMA1 Antigen Fragments

“…The parasite strains used in the study, included the low-virulence T. gondii DX strain and highly virulent RH strain (50174™, ATCC ® , Manassas, VA, USA), which were maintained in vivo through laboratory mice and in vitro on human foreskin fibroblasts (Hs27, CRL−1634™, ATCC ® , Manassas, VA, USA), respectively, as described previously [35]. The DX strain was used to induce experimental T. gondii infection in mice, while the RH strain was utilized as a source of native parasite antigens (Toxoplasma gondii lysate antigen, TLA) and DNA for cloning procedures involved in recombinant antigen production.…”

“…Tetravalent recombinant chimeric proteins containing different fragments of the T. gondii AMA1 antigen including AMA1 domain I -SAG2-GRA1-ROP1 L (A N SGR), AMA1 domains II,III -SAG2-GRA1-ROP1 L (A C SGR) and AMA1 full protein -SAG2-GRA1-ROP1 L -(A F SGR) were produced, purified and analyzed according to procedures described previously [35,42].…”

“…Thus, the aim of the study was to evaluate the immunogenic and protective efficacies of three recombinant chimeric T. gondii proteins containing different fragments of the AMA1 antigen. The experimental design of the present work was based on our previous observations, which led to the selection of one particularly promising chimeric antigen constituting a potential object for further research on specific anti-Toxoplasma prophylaxis due to its high immunogenic and immunoprotective potential leading to high but not complete protection against cyst formation in mice [35]. Thus, an attempt was made to further boost the immunoprotective capacity of the SAG2-GRA1-ROP1 L (SGR) fusion protein by incorporating different portions of the T. gondii apical membrane antigen−1 (AMA1) into its structure.…”