The Genome Sequence of Brucella abortus vaccine strain A19 provides insights on its virulence attenuation compared to Brucella abortus strain 9-941

Bioinformatics approach for structure modeling, vaccine design, and molecular docking of Brucella candidate proteins BvrR, OMP25, and OMP31

Brucellosis is a zoonotic disease with significant economic and healthcare costs. Despite the eradication efforts, the disease persists. Vaccines prevent disease in animals while antibiotics cure humans with limitations. This study aims to design vaccines and drugs for brucellosis in animals and humans, using protein modeling, epitope prediction, and molecular docking of the target proteins (BvrR, OMP25, and OMP31). Tertiary structure models of three target proteins were constructed and assessed using RMSD, TM-score, C-score, Z-score, and ERRAT. The best models selected from AlphaFold and I-TASSER due to their superior performance according to CASP 12 - CASP 15 were chosen for further analysis. The motif analysis of best models using MotifFinder revealed two, five, and five protein binding motifs, however, the Motif Scan identified seven, six, and eight Post-Translational Modification sites (PTMs) in the BvrR, OMP25, and OMP31 proteins, respectively. Dominant B cell epitopes were predicted at (44-63, 85-93, 126-137, 193-205, and 208-237), (26-46, 52-71, 98-114, 142-155, and 183-200), and (29-45, 58-82, 119-142, 177-198, and 222-251) for the three target proteins. Additionally, cytotoxic T lymphocyte epitopes were detected at (173-181, 189-197, and 202-210), (61-69, 91-99, 159-167, and 181-189), and (3-11, 24-32, 167-175, and 216-224), while T helper lymphocyte epitopes were displayed at (39-53, 57-65, 150-158, 163-171), (79-87, 95-108, 115-123, 128-142, and 189-197), and (39-47, 109-123, 216-224, and 245-253), for the respective target protein. Furthermore, structure-based virtual screening of the ZINC and DrugBank databases using the docking MOE program was followed by ADMET analysis. The best five compounds of the ZINC database revealed docking scores ranged from (- 16.8744 to - 15.1922), (- 16.0424 to - 14.1645), and (- 14.7566 to - 13.3222) for the BvrR, OMP25, and OMP31, respectively. These compounds had good ADMET parameters and no cytotoxicity, while DrugBank compounds didn't meet Lipinski's rule criteria. Therefore, the five selected compounds from the ZINC20 databases may fulfill the pharmacokinetics and could be considered lead molecules for potentially inhibiting Brucella's proteins.

Gated nanoprobe utilizing metal-organic frameworks for identifying and distinguishing between the wild strains and the vaccine strains of brucella

In the assay for Brucella, the identification and differentiation of wild strains and vaccine strains present a significant challenge. Currently, there aren't any commercially available product to address this issue. In this study, we have developed a novel gated nanoprobe by utilizing Metal-Organic Frameworks (MOFs) as a scaffold and hairpin DNA as a "gating switch". Specifically, Probe 1 with hairpin structure (P1h) targets a gene that is present in both wild strains Y3 (B. melitensis biovar 3) and vaccine strains A19 (Brucella abortus strains A19). We successfully applied this probe to screen positive samples of Brucella without any cross-reactivity with other substances. Additionally, we identified another specific gene exclusively found in wild strains, which serves as Probe 2 with hairpin structure (P2h) to confirm the strain type. Simultaneous detachment of both P1h and P2h from the MOFs leads to the release of Rhodamine 6G (Rho 6G) and Fluorescein (Flu), specifically indicating the presence of wild strains. If only P1h detaches and the Flu signal is detected, it suggests the presence of vaccine strains. Importantly, this method offers high accuracy, with a detection rate of 90% and a recovery rate of 94.71% to 107.65%, while avoiding cross-reactions with MO and TB. This one-step experiment provides reliable identification and differentiation of Y3 and A19, addressing concerns related to long periodicity, interference from individual variations, and the complex design of primers in existing laboratory methods. Furthermore, our approach successfully detects target 1 (T1) and target 2 (T2) at concentrations ranging from 10-6 M to 10-9 M, with a detection limit of 6.7 × 10-10 M and 6.4 × 10-10 M, respectively. Importantly, our strategy is cost-effective (around $1) and offers higher detection efficiency compared to traditional laboratory methods.

Novel multi-epitope vaccine against bovine brucellosis: approach from immunoinformatics to expression

Brucellosis is a zoonotic caused by the Brucella which is a well-known infectious disease agent in domestic animals and if transmitted, it can cause infection in humans. Because brucellosis is contagious, its control depends on the eradication of the animal disease in farms. There are two vaccines based on the killed and/or weakened bacteria against B. melitensis and B. abortus, but no recombinant vaccine is available for preventing the disease. The present study was designed to develop a multi-epitope vaccine against of B. melitensis and B. abortus using virB10, Omp31 and Omp16 antigens by the prediction of T lymphocytes, T cell cytotoxicity and IFN-γ epitopes. 50S L7/L12 Ribosomal protein from Mycobacterium tuberculosis was used as a bovine TLR4 and TLR9 agonist. GPGPG, AAY and KK linkers were used as a linker. Brucella construct was well-integrated in the pET-32a Shuttle vector with BamHI and HindIII restriction enzymes. The final construct contained 769 amino acids, that it was soluble protein of about ∼82 kDa after expression in the Escherichia coli SHuffle host. Modeled protein analysis based on the tertiary structure validation, molecular docking studies, molecular dynamics simulations results like RMSD, Gyration and RMSF as well as MM/PBSA analysis showed that this protein has a stable construct and is capable being in interaction with bovine TLR4 and TLR9. Analysis of the data obtained suggests that the proposed vaccine can induce the immune response by stimulating T- and B-cells, and may be used for prevention and remedial purposes, against B. melitensis and B. abortus.Communicated by Ramaswamy H. Sarma.

Recent advancement, immune responses, and mechanism of action of various vaccines against intracellular bacterial infections

Emerging and re-emerging bacterial infections are a serious threat to human and animal health. Extracellular bacteria are free-living, while facultative intracellular bacteria replicate inside eukaryotic host cells. Many serious human illnesses are now known to be caused by intracellular bacteria such as Salmonella enterica, Escherichia coli, Staphylococcus aureus, Rickettsia massiliae, Chlamydia species, Brucella abortus, Mycobacterium tuberculosis and Listeria monocytogenes, which result in substantial morbidity and mortality. Pathogens like Mycobacterium, Brucella, MRSA, Shigella, Listeria, and Salmonella can infiltrate and persist in mammalian host cells, particularly macrophages, where they proliferate and establish a repository, resulting in chronic and recurrent infections. The current treatment for these bacteria involves the application of narrow-spectrum antibiotics. FDA-approved vaccines against obligate intracellular bacterial infections are lacking. The development of vaccines against intracellular pathogenic bacteria are more difficult because host defense against these bacteria requires the activation of the cell-mediated pathway of the immune system, such as CD8+ T and CD4+ T. However, different types of vaccines, including live, attenuated, subunit, killed whole cell, nano-based and DNA vaccines are currently in clinical trials. Substantial development has been made in various vaccine strategies against intracellular pathogenic bacteria. This review focuses on the mechanism of intracellular bacterial infection, host immune response, and recent advancements in vaccine development strategies against various obligate intracellular bacterial infections.