Discovery of novel vaccine candidates based on the immunogenic epitopes derived from Toxoplasma membrane proteins.

Abstract

Purpose: Due to the widespread distribution and importance of Toxoplasma gondii infection as a parasitic zoonosis, multi-epitope vaccine design was implemented using a set of immunodominant epitopes screened out of a wide scope of membrane proteins.

Materials and methods: On this basis, 5 vaccine candidates were created using linkers ([GGGGS]₂, KK, AAY, GPGPG, GDGDG, EAAAK) and adjuvants (RS-09 peptide, Mycobacterium tuberculosis resuscitation-promoting factor E [RpfE] and 50S ribosomal protein, human interferon [IFN]-γ).

Results: Polytopes with RS-09 alone (Toxo-App) and with IFN-γ (Toxo-Apfn), and one with 50S ribosomal protein (Toxo-Ribos) showed the highest immunogenicity during in silico prediction, and their 3-dimensional structure was refined. Protein-protein docking and molecular dynamics simulation analysis was done between the Toxo-App and human toll-like receptor (TLR)-4, rendering a stable connection. Codon optimization and in silico cloning was done ultimately for the selected vaccine candidate.

Conclusion: In conclusion, potent multi-epitope vaccine candidates were designed against toxoplasmosis using a diverse set of in silico techniques, while further wet experiments are recommended.