Reverse vaccinology-based identification and in silico characterization of immunogenic membrane proteins of Salmonella Typhimurium as novel vaccine targets against multidrug-resistant infections.

Abstract

Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is a leading cause of salmonellosis, gastroenteritis, sepsis, and reactive arthritis. Transmission primarily occurs through contaminated water, eggs, meat, and dairy products. The disease disproportionately affects developing nations, where young children, the elderly, and immunocompromised individuals face high risks of severe morbidity and mortality. Its ability to evade host immune defenses and acquire multidrug resistance (MDR) exacerbates global public health challenges. Currently, no licensed human vaccine is available, underscoring the urgent need for targeted vaccine development.

Methods: This study utilized a reverse vaccinology approach and in silico strategies to identify highly immunogenic membrane proteins as potential vaccine candidates. The complete proteome of S. Typhimurium was screened for membrane-associated candidates using the SOSUI server. Antigenicity was evaluated using VaxiJen v2.0 (threshold ≥ 0.9), and allergenicity was assessed using AllerTOP v1.1. To ensure vaccine safety, homologous proteins were excluded based on PSI-BLAST analysis against the human proteome, and toxicity was predicted using ToxinPred. The immunogenic potential was further evaluated through C-ImmSim immune simulation software. B-cell and T-cell epitopes were predicted using ABCpred and the Immune Epitope Database (IEDB). Physicochemical characteristics were analyzed with ProtParam and TMHMM 2.0. Finally, BLASTp analysis was used to confirm the conservation of the selected proteins across MDR clinical isolates.

Results: Nine membrane proteins were prioritized based on strong antigenicity, non-allergenicity, non-toxicity, favorable epitope profiles, and physicochemical stability. All proteins were highly conserved in MDR isolates, supporting their utility for broad-spectrum vaccine development.

Conclusion: These targets show promising potential for developing a broadly protective multi-epitope vaccine against S. Typhimurium. However, in vitro and in vivo experimental validation is essential to confirm their immunogenicity and protective efficacy.