In silico evaluation of Toxoplasma gondii rhoptry neck proteins (TgRONs) for potential immunogenic epitopes

This immunoinformatics-based study utilized a suite of online predictive tools to characterize the structural and immunogenic properties of Toxoplasma gondii rhoptry neck proteins (TgRONs). Full-length amino acid sequences of TgRON2, TgRON4, TgRON4L1, TgRON5, TgRON8, TgRON9, TgRON10, and TgRON13 were retrieved from ToxoDB and subjected to comprehensive analysis. Except for TgRON4L1, all proteins were predicted to be possess antigenic potential, with none identified as allergenic. Solubility predictions indicated that TgRON9 and TgRON10 are the most likely to be expressed as soluble antigens. Aliphatic index values, ranging from 51.17 to 84.63, suggest acceptable thermostability, while negative GRAVY scores across all proteins indicate favorable hydrophilicity. Additionally, multiple post-translational modification sites were identified, underscoring the functional complexity of these antigens. Initial 3D structure modeling showed that 60.21-92.41 % of residues fell within favored regions on Ramachandran plots, with refinement increasing this to 92.27-98.58 %, reflecting substantial improvements in structural quality. Several potential T-cell (CTL and HTL) and B-cell epitopes were predicted for all candidate proteins. Immune simulation models further suggested that these antigens could elicit robust humoral and cellular immune responses when delivered in a three-dose regimen at four-week intervals. These findings offer valuable preliminary insights and support the further investigation of TgRONs, particularly TgRON9 and TgRON10, as promising targets for experimental validation in the development of vaccines against T. gondii infection.