James Kimotho

Antimicrobial resistance represents a global health burden requiring innovative therapeutic strategies. The antibacterial properties of Salvia officinalis (S. officinalis) are attributed to its bioactive compounds. The present study aimed to investigate the antimicrobial activity of nano-encapsulated S. officinalis leaf extract against methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii (A. baumannii). The crude extract of S. officinalis was subjected to methanolic extraction, and the resulting methanolic fraction was analyzed through phytochemical screening. Phytocompounds were identified using gas chromatography-mass spectrometry (GC-MS), and their potential mechanisms of action were evaluated in silico. The S. officinalis extract was nano-formulated using chitosan and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and UV-visible spectroscopy. Antibacterial activity of the nano-formulation against MRSA and A. baumannii was assessed using agar well diffusion, broth microdilution, and minimum bactericidal concentration analysis. Qualitative phytochemical analysis revealed the presence of flavonoids, alkaloids, tannins, saponins, and terpenoids. The GC‑MS analysis demonstrated 15 peaks, representing 14 distinct compounds, with one compound (3,7,11,15‑tetramethyl‑2‑hexadecen‑1‑ol) eluting at two retention times. Chitosan nanoparticle formation was confirmed by an absorption peak near 290 nm. The functional groups of chitosan nanoparticles included hydroxyl (-OH) and amide (-NH₂) groups, along with C–H, C–N, C–O, and P=O stretching. The SEM imaging exhibited relatively homogeneous, well-dispersed, spherical nanoparticles. The antimicrobial efficacy of S. officinalis chitosan nanoparticles was concentration-dependent, reaching maximum inhibition zones of 21 ± 0.5 mm against MRSA and 17 ± 1.5 mm against A. baumannii at 500 µg/mL. Additionally, susceptibility testing revealed minimum inhibitory concentrations of 62.5 µg/mL and 125 µg/mL, and minimum bactericidal concentrations of 125 µg/mL and 500 µg/mL against MRSA and A. baumannii, respectively. Molecular docking analysis indicated that phytocompounds within the methanolic extract exhibited binding affinity toward penicillin-binding protein 2a (PBP2a) and the carbapenem-associated outer membrane protein (CarO). The interactions between the phytochemicals and protein targets indicated that binding to catalytic sites could inhibit the function of these resistance-associated proteins, potentially reducing antibiotic degradation. The biosynthesized S. officinalis chitosan nanoparticles exhibited strong antimicrobial activity against multidrug-resistant bacterial isolates, supporting their potential as antimicrobial agents.

Papillomaviruses can infect animals and humans, causing benign lesions and cancer. Chimeric vaccines may address the limited coverage of current papillomavirus vaccines by providing cross-type immunity. The present study focused on the in silico design of a chimeric mRNA vaccine targeting a wide range of human papillomaviruses (HPV). The study incorporated 25 amino acid sequences derived from L1 and L2 capsid proteins of 14 high-risk and 11 low-risk HPV strains. These sequences underwent multiple sequence alignment, and the resulting sequences were used to develop consensus sequences. Computational approaches were then applied to predict and identify immunodominant T-cell and B-cell epitopes. The mRNA vaccine structure was designed by merging codon-optimized multi-epitope chimeric peptides with regulatory components that enhance both transcription and translation efficiency. The present study identified 19 T and 6 B cell epitopes, which were evaluated as non-toxic, non-allergenic, highly antigenic, and fully or partially conserved. The final multi-epitope peptide vaccine had a molecular weight of 60,161.29 kDa, a theoretical isoelectric point (pI) of 9.44, a solubility index of 0.451, and an antigenicity score of 0.9178. The mRNA vaccine exhibited a stable mRNA structure with a minimum free energy of -731.10 kcal/mol and an estimated molecular weight of 644.98 kDa. The proposed vaccine demonstrated no cross-affinity with the human genome and attained a worldwide population coverage rate of 86.24%. The vaccine formed a stable docking complex and exhibited strong interactions with major histocompatibility class I and class II molecules, as well as Toll-like receptor 4 (TLR4), Toll-like receptor 9 (TLR9), and the B-cell receptor. Binding affinities were assessed based on free energy (ΔG) values of -34.01 kcal/mol and -20.77 kcal/mol for major histocompatibility complex (MHC) class I and II, respectively, -1377.5 kcal/mol for TLR4, -24.19 kcal/mol for TLR9, and -34.41 kcal/mol for the B-cell receptor. This vaccine triggered both antibody and cell-mediated immune responses and increasing levels of IFN-γ and the interleukins IL-2, IL-10, and IL-12. This vaccine is considered preventive against multiple HPV infections. Nonetheless, in vitro and in vivo investigations are necessary to validate the safety and efficacy of this vaccine.