Utilizing immuno-informatics for brucella vaccine development with multi-epitope IgV_CTLA-4 domain fusion

Abstract

Background: In vivo and in vitro experiments confirmed the antigenic and immunogenic properties of the immuno-informatics-developed vaccine for Brucella. Predicting the Brucella vaccine using Omp2b and Omp31 protein nucleotide sequences, combined with molecular docking technology, enhances accuracy. The Omp2b and Omp31 protein combination proves more effective in Brucella vaccine development. Aim: Development of a potential high-afÏnity vaccine design containing a variable fragment of CTLA-4 against Brucella. Materials and Methods: The amino acid sequences of Omp2b, Omp31 and IgV_ CTLA4 were retrieved from GenBank. Physicochemical parameters were calculated using Expasy software, while transmembrane domain and protein signal peptide data were analyzed using the TMHMM online server. T and B cell epitopes were identified using the IEDB online server. Secondary structure prediction was performed using the PRABI online program. Furthermore, three-dimensional structures of proteins and vaccines were predicted using the I-TASSER online programs. Results: The Omp2b protein consists of 362 amino acid residues with a molecular weight of 38,676.57. Its molecular structure is represented by C1734H2578N456O544S5, and its theoretical pI value is 4.58. The instability index (II) of Omp2b is 23.54. The Omp31 protein consists of 240 amino acid residues with a molecular weight of 25,323.20. Its molecular structure is represented by C1135H1725N297O354S4, and its theoretical pI value is 5.22. The instability index (II) of Omp31 is 8.61. The T-cell epitope potential sequences of Omp2b and Omp31 proteins were examined using the IEDB-MHCII online server, and the three potential T-cell sequences with the lowest adjusted rank and highest afÏnity were selected. Conclusions: 1. Determined the amino acid sequences, molecular structures, atomic compositions, weights, theoretical isoelectric points, instability index, aliphatic index, grand averages of hydropathicity (GRAVY), and pinpointed their domain locations for the Omp2b, Omp31, and IgV_CTLA4 proteins. 2. Predicted T and B cell epitopes of Omp2b-Omp31 and IgV_CTLA4 proteins and developed a three-dimensional structural model of the vaccine.