Abstract

Vaccination is the only feasible way for appropriate prevention of Neospora caninum infection. The present in silico study was done to evaluate the physico-chemical properties and determine immunogenic epitopes of N. caninum SAG1 protein as a possible vaccine candidate. Web-based tools were used to predict physico-chemical properties, antigenicity, allergenicity, solubility, post-translational modification (PTM) sites, transmembrane domains and signal peptide, secondary and tertiary structures as well as intrinsically disordered regions, followed by identification and screening of potential linear and conformational B-cell epitopes and those peptides having affinity to bind mouse major histocompatibility complex (MHC) and cytotoxic T lymphocyte (CTL). The protein was stable in a test tube, had 319 residues with a molecular weight of 33.07 kDa, representing aliphatic index of 76.68 (thermotolerant) and GRAVY score of 0.031 (hydrophobic). There were 42 PTM sites and an N-terminally-located signal peptide in the sequence. Secondary structure comprised mostly by random coils, followed by strands and helices. Ramachandran plot of the refined model showed 71.7, 24.9, 3.0 and 0.4 residues in the favored, additional allowed, generously allowed and disallowed regions, correspondingly. Additionally, various potential B-cell (linear and conformational), CTL and MHC-binding epitopes were predicted for N. caninum SAG1. The findings of the present in silico study are a premise for vaccination strategies against neosporosis. © 2021