Toxoplasma gondii Microneme Protein 3 (TgMIC3): Computational Probing for Improved Vaccine Design

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.

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.

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.