Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 21 1 2026 05 19 105 116 Masoud Foroutan Department of Basic Medical Sciences, Faculty of Medicine, Abadan University of Medical Sciences, Abadan, Iran Hamidreza Majidiani 1. Healthy Aging Research Centre, Neyshabur University of Medical Sciences, Neyshabur, Iran 2. Department of Basic Medical Sciences, Neyshabur University of Medical Sciences, Neyshabur, Iran Fatemeh Ghaffarifar Department of Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Elaheh Karimzadeh-Soureshjani Student Research Committee, Abadan University of Medical Sciences, Abadan, Iran Amir Karimipour-Saryazdi Department of Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Ali Dalir Ghaffari Department of Parasitology and Mycology, Faculty of Medicine, Shahed University, Tehran, Iran John Horton Tropical Projects, Hitchin, United Kingdom 2025 03 09 2026 06 07 Background: Microneme protein 3 (MIC3) is a key adhesion molecule in Toxoplasma gondii that is expressed during multiple stages of infection. We aimed to computationally characterize the immunological and structural features of the T. gondii MIC3 protein to assess its potential suitability as a vaccine candidate. Methods: A comprehensive set of bioinformatics tools and web servers was employed to predict the physicochemical properties, allergenicity, antigenicity, solubility, post-translational modification sites, subcellular localization, transmembrane domains, signal peptides, secondary and tertiary structures, potential B- and T-lymphocyte epitopes, and simulated immune responses of the TgMIC3 protein. Results: A total of 75 post-translational modification sites were predicted in TgMIC3. Furthermore, secondary structure analysis using GOR IV, SOPMA, and NetSurfP-3.0 indicated that random coils and extended strands were the predominant structural elements. In addition, several high-affinity B- and T-cell epitopes were identified across the protein sequence. Subsequent structural validation revealed that 82.91% and 98.60% of residues were located in favored regions in the initial and refined 3D models, respectively. The findings of the allergenicity and antigenicity assessments indicated that the MIC3 antigen seemed to be a non-allergen with an immunogenic nature. Moreover, immune simulation using the C-ImmSim server demonstrated that TgMIC3 could induce robust humoral and cell-mediated immune responses following three simulated antigen administrations. Conclusion: This study provides foundational computational evidence supporting the potential of TgMIC3 as a vaccine antigen and offers a useful framework for future experimental investigations targeting vaccine development against acute and latent toxoplasmosis. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/4540 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/4540/1484