Bartonella henselae is a Gram-negative bacterium causing a variety of clinical symptoms, ranging from cat-scratch disease to severe systemic infections, and it is primarily transmitted by infected fleas. Its status as an emerging zoonotic pathogen and its capacity to persist within host erythrocytes and endothelial cells emphasize its clinical significance. Despite progress in understanding its pathogenesis, limited knowledge exists about the virulence factors and regulatory mechanisms specific to the B. henselae strain Houston-1. Exploring these aspects is crucial for targeted therapeutic strategies against this versatile pathogen. Using reverse-vaccinology-based subtractive proteomics, this research aimed to identify the most antigenic proteins for formulating a multi-epitope vaccine against the B. henselae strain Houston-1. One crucial virulent and antigenic protein, the PAS domain-containing sensor histidine kinase protein, was identified. Subsequently, the identification of B-cell and T-cell epitopes for the specified protein was carried out and the evaluated epitopes were checked for their antigenicity, allergenicity, solubility, MHC binding capability, and toxicity. The filtered epitopes were merged using linkers and an adjuvant to create a multi-epitope vaccine construct. The structure was then refined, with 92.3% of amino acids falling within the allowed regions. Docking of the human receptor (TLR4) with the vaccine construct was performed and demonstrated a binding energy of −1047.2 Kcal/mol with more interactions. Molecular dynamic simulations confirmed the stability of this docked complex, emphasizing the conformation and interactions between the molecules. Further experimental validation is necessary to evaluate its effectiveness against B. henselae.

A novel tick-borne orthonairovirus called the Yezo virus (YEZV), primarily transmitted by the Ixodes persulcatus tick, has been recently discovered and poses significant threats to human health. The YEZV is considered endemic in Japan and China. Clinical symptoms associated with this virus include thrombocytopenia, fatigue, headache, leukopenia, fever, depression, and neurological complications ranging from mild febrile illness to severe outcomes like meningitis and encephalitis. At present, there is no treatment or vaccine readily accessible for this pathogenic virus. Therefore, this research employed an immunoinformatics approach to pinpoint potential vaccine targets within the YEZV through an extensive examination of its structural proteins. Three structural proteins were chosen using specific criteria to pinpoint T-cell and B-cell epitopes, which were subsequently validated through interferon-gamma induction. Six overlapping epitopes for cytotoxic T-lymphocytes (CTL), helper T-lymphocytes (HTL), and linear B-lymphocytes (LBL) were selected to construct a multi-epitope vaccine, achieving a 92.29% coverage of the global population. These epitopes were then fused with the 50S ribosomal protein L7/L12 adjuvant to improve protection against international strains. The three-dimensional structure of the designed vaccine construct underwent an extensive evaluation through structural analysis. Following molecular docking studies, the YEZV vaccine construct emerged as a candidate for further investigation, showing the lowest binding energy (−78.7 kcal/mol) along with favorable physiochemical and immunological properties. Immune simulation and molecular dynamics studies demonstrated its stability and potential to induce a strong immune response within the host cells. This comprehensive analysis indicates that the designed vaccine construct could offer protection against the YEZV. It is crucial to conduct additional in vitro and in vivo experiments to verify its safety and effectiveness.

Background: The current study explored the cholinesterase inhibitory activities of some thiosemicarbazone derivatives bearing 2,4-dichloro phenylacetic acid scaffold. Objective: This study aimed to screen the synthesized derivatives for their in vitro acetylcholine and butyrylcholinesterase inhibition. Methods: These compounds were synthesized by refluxing 2,4-dichloro phenylacetic acid with sulfuric acid in ethanol to get the ester, which was further refluxed with thiosemicarbazide in ethanol to get the desired compound (2). Different benzaldehydes were treated with compound (2) in ethanol having a catalytic amount of acetic acid to get thiosemicarbazones. Results: In the series, seven compounds, including compounds 2c, 2a, 2b, 2d, 2g, 2e, and 2f, displayed excellent acetylcholinesterase inhibition activities in the range of IC₅₀ values from 41.51 ± 3.88 to 95.48 ± 0.70 μM, surpassing than the standard galantamine (IC₅₀ = 104.5 ± 1.20 μM). Also, compounds 2a, 2g, 2h, 2f, 2b, and 2d with IC₅₀ values ranging from 64.47 ± 2.74 to 80.62 ± 0.73 μM exhibited potent inhibition against butyrylcholinesterase enzyme, being similar to the standard galantamine (IC₅₀ = 156.8 ± 1.50 μM). The molecular docking investigation was performed to assess the binding affinity of the compounds with the active site of the enzyme. These compounds, along with the docked complexes, specifically AChE-compound 2a and BuChE-compound 2g, were chosen and subjected to 100-nanosecond molecular dynamics simulations. The simulations demonstrated strong stability of the ligands within the active pockets of AChE and BuChE enzymes. Conclusion: These derivatives exhibited superior acetylcholinesterase and butyrylcholinesterase inhibitory activities compared to galantamine, with molecular docking and dynamic simulations confirming their strong binding affinity with the active sites of the enzymes.

Rickettsia felis, responsible for flea-borne spotted fever, is a rising zoonotic pathogen posing an increasing global threat due to its expanding geographical distribution. The rise in antibiotic-resistant strains of this pathogen underscores the urgent need for new therapeutic interventions. This study employed a comprehensive subtractive proteomics analysis of the R. felis proteome, aiming to identify essential, non-host homologous, and pathogen-specific proteins, which were subsequently evaluated as potential new drug targets. These findings offer valuable insights into the development of therapeutic strategies against rickettsiosis. The analysis revealed 343 proteins that are non-homologous to the host, including 108 essential proteins, 25 unique metabolic pathways, and 11 distinct proteins. Out of these, 10 proteins were druggable in which two associated with virulence, and one related to resistance (succinate dehydrogenase). Through a rigorous screening process and extensive literature review, succinate dehydrogenase emerged as a promising drug target. Protein interaction partners for succinate dehydrogenase were identified using the STRING database. To further assess the functionality of succinate dehydrogenase, structure-based studies were conducted. Approximately 18,000 ZINC compounds were screened, leading to the finding of six potential inhibitors: ZINC67847806, ZINC67982856, ZINC67974679, ZINC67895371, ZINC05668040, and ZINC05670149. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiling confirmed that most compounds met the preferred pharmacokinetic properties, except for ZINC67895371 and ZINC67847806, which exhibited positive ames test results, and ZINC05670149, ZINC67895371, and ZINC67847806, showed hepatotoxicity. All compounds were found to be non-sensitizing to the skin. Based on these findings, further experimental validation of ZINC67974679, ZINC67982856, and ZINC05668040 is recommended.