Imam Hossein University

Enterobactin, a high-affinity siderophore produced by Escherichia coli and other enteric pathogens, plays a critical role in bacterial iron acquisition and virulence. By sequestering iron from host environments, enterobactin enables bacterial survival and proliferation, even under iron-limited conditions typical of host tissues. This review explores the biosynthesis and regulation of enterobactin, highlighting its contribution to bacterial pathogenesis and immune evasion. We discuss the potential of targeting enterobactin for the development of live-attenuated vaccines, emphasizing the attenuation of virulence through genetic knockout of enterobactin biosynthesis genes (e.g. entB). Additionally, we examine enterobactin as a promising target for novel antimicrobial strategies, including small-molecule inhibitors and siderophore-based "Trojan horse" antibiotics. Beyond medical applications, we also explore the biotechnological and environmental potential of enterobactin, such as its use in bioremediation and drug delivery systems. Finally, we identify key gaps in current research and propose future directions for harnessing enterobactin to combat bacterial infections and address global health challenges. This review underscores the multifaceted role of enterobactin in bacterial biology and its potential as a cornerstone for innovative therapeutic and biotechnological applications.

Typhoid fever, caused by Salmonella enteritidis serovar Typhi (S. Typhi), remains a significant global health challenge, especially in regions with poor sanitation. Despite available vaccines, limitations such as short-term efficacy and variable immune responses necessitate novel strategies. Here, we designed a multi-protein chimeric protein vaccine targeting S. Typhi by integrating three key antigens: SteD (an immune-evasion transmembrane effector) (whole protein), flagellin (D1 domain), and STIV (Salmonella Typhi invasion protein) (whole protein). Proteins were linked via rigid EAAAK linkers to enhance stability. The construct exhibited high antigenicity (VaxiJen score:0. 9228) and favorable physicochemical properties (ProtParam), with non-allergenic (AlgPred) and non-toxic (ToxinPred) profiles. Structural analysis revealed a stable 3D model (I-TASSER/Phyre2/RaptorX), validated by Ramachandran plot (>90 % favored regions), ProSA z-score of -5.54, and ERRAT. B-cell and T-cell epitopes predicted by IEDB, ABCPred, and Discotope 2.0 demonstrated strong binding to HLA alleles. Molecular docking confirmed robust interactions with TLR-4 (PDB:2Z63) and TLR-5 (PDB:3V44), while 100-ns MD simulations (NAMD/VMD) affirmed complex stability (low RMSD/RMSF). Immune simulations (C-ImmSim) predicted potent humoral and cellular responses, including elevated IgG/IgM and Th1/Th2 cytokines. This in silico study proposes a promising vaccine candidate with high theoretical immunogenicity and structural integrity, warranting further in vitro and in vivo validation.

This study provides an analysis of glass composed of TeO₂, MoO₃, and Nb₂O₅, focusing on its gamma ray shielding capabilities. The assessment of these capabilities was conducted using Geant4 simulations, which evaluated parameters such as the mass attenuation coefficient (MAC), transmission fractions, effective atomic number, half-value layer (HVL), and exposure buildup factor for photon energies ranging from 0.015 to 10 MeV. The comparison between the theoretical values obtained from Phy-X software and the simulated values from Geant4 revealed a deviation of less than 2%, indicating strong agreement across all glass samples at the examined energy levels. The MAC values for the selected samples varied from 35.57 to 0.034 cm²/g, with glasses G-2 and G-3 demonstrating the highest values. The results for the linear attenuation coefficient (LAC) indicated that as photon energy increased, the ability of photons to penetrate the glass also increased. At 662 keV, the LAC values of the tellurite glass were compared with those of lead glasses, revealing that G-3 and G-2 exhibited attenuation results comparable to 20% Pb glass. The analysis of the HVL indicated that the selected glasses showed values almost equal to other tellurite glasses containing lead and tungsten, highlighting their effective performance. Additionally, the findings demonstrated that the transmission factor rises with increasing photon energy. The radiation shielding efficiency results indicated that thicker glass samples absorb more photons, resulting in reduced radiation transmission and enhanced radiation protection effectiveness (RPE). The findings show that the radiation shielding efficiency for energies below 150 kV is close to 100%. The glasses made from TeO₂, MoO₃, and Nb₂O₅ are considered highly promising for applications requiring effective shielding against high-energy photons, while also maintaining high radiation shielding efficiency.