IN SILICO SCREENING OF ANTIGENS FOR A POTENTIAL VACCINE CANDIDATE AGAINST Toxoplasma gondii IN GOATS

Résumé

Toxoplasma gondii (T. gondii), an obligate intracellular parasite, is a significant zoonotic pathogen causing economic losses in livestock and public health risks. In goats, T. gondii infections can lead to reproductive disorders such as abortion and neonatal mortality, necessitating effective control measures. Vaccination is a promising strategy, but the development of vaccines against T. gondii remains challenging. This study, therefore, employed in silico approaches to identify potential antigens suitable for vaccine development against T. gondii in goats. A novel multiepitope vaccine was designed using immunoinformatics techniques targeting T. gondii MIC, ROP 8, 16 and 18 and GRA7 antigens, consisting of antigenic and non-allergenic T-cell epitopes and B-cell epitopes. These screened epitopes were fused together using AAY, GPGPG and KK linkers. The 50S ribosomal protein L7/L12 with the accession number (P9WHE3) was used as an adjuvant to enhance the performance of the vaccine. The tertiary model of the proposed vaccine candidate was predicted and validated to confirm the structural quality of the vaccine. The designed vaccine was highly antigenic (0.5183), with molecular weight of 41.02 kDa, instability and aliphatic index of 29.06 and 93.97, respectively; this classified the vaccine as stable. The GRAVY score of 0.119 showed that the vaccine is slightly soluble. Using immunoinformatics approaches, nine T-cell and six B-cell epitopes were found from the chosen goat toxoplasma antigens. Based on the in-silico experiment, the multi-epitope peptide-based vaccine was found to be both non-allergic and highly antigenic. Molecular docking, dynamics simulation, in silico codon optimization, cloning, expression, and vaccine built in silico/online immunological simulations should all be performed on the developed peptide-based vaccine to determine the protective efficacy of the vaccine construct against T. gondii infection as well as its safety