RESUMO
BACKGROUND: Yellow fever is a mosquito-borne viral hemorrhagic disease transmitted by several species of virus-infected mosquitoes endemic to tropical regions of Central and South America and Africa. Earlier in the twentieth century, mass vaccination integrated with mosquito control was implemented to eradicate the yellow fever virus. However, regular outbreaks occur in these regions which pose a threat to travelers and residents of Africa and South America. There is no specific antiviral therapy, but there can be an effective peptide-based vaccine candidate to combat infection caused by the virus. Therefore, the study aims to design a multi-epitope-based subunit vaccine (MESV) construct against the yellow fever virus to reduce the time and cost using reverse vaccinology (RV) approach. METHODS: Yellow fever virus contains 10,233 nucleotides that encode for 10 proteins (C, prM, E, NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) including 3 structural and 7 non-structural proteins. Structural proteins-precursor membrane protein (prM) and envelope protein (E)-were taken as a target for B cell and T cell epitope screening. Further, various immunoinformatics approaches were employed to FASTA sequences of structural proteins to retrieve B cell and T cell epitopes. MESV was constructed from these epitopes based on allergenicity, antigenicity and immunogenicity, toxicity, conservancy, and population coverage followed by structure prediction. The efficacy of the MESV construct to bind with human TLR-3, TLR-4, and TLR-8 were evaluated using molecular docking and simulation studies. Finally, in-silico cloning of vaccine construct was performed withpBR322 Escherichia coli expression system using codon optimization. RESULTS: Predicted epitopes evaluated and selected for MESV construction were found stable, non-allergenic, highly antigenic, and global population coverage of 68.03% according to in-silico analysis. However, this can be further tested in in-vitro and in-vivo investigations. Epitopes were sequentially merged to construct a MESV consisting of 393 amino acids using adjuvant and linkers. Molecular docking and simulation studies revealed stable and high-affinity interactions. Furthermore, in-silico immune response graphs showed effective immune response generation. Finally, higher CAI value ensured high gene expression of vaccine in the host cell. CONCLUSION: The designed MESV construct in the present in-silico study can be effective in generating an immune response against the yellow fever virus. Therefore, to prevent yellow fever, it can be an effective vaccine candidate. However, further downstream, in-vitro study is required.
RESUMO
There is great concern in the medical community due to rapid increase in antibiotic resistance, causing 700,000 deaths annually worldwide. Therefore, there is paramount need to develop novel and innovative antibacterial agents active against resistant bacterial strains. DNA gyrase is a crucial enzyme in bacterial replication that is absent in eukaryotes, making it effective curative target for antibacterials. To identify potential DNA gyrase inhibitors by virtual screening of NCI database using a 3-step approach. A total of 271 compounds with known IC50 values against Escherichia coli DNA GyrA were selected to develop a pharmacophore model for dual screening approach to identify new potential hits from the NCI database. In the second step, the NCI database was also screened using in-house built NN-QSAR model. Molecular docking of common 5298 compounds screened from both methods were performed against E. coli DNA GyrA (PDB id- 6RKU), and 3004 compounds are reported to exhibit lower binding energies than ciprofloxacin (-6.77 Kcal/mol). The top three compounds (NCI371878, NCI371876 and NCI142159) reported with binding energy of -13.5, -13.19 and -13.03 Kcal/mol were further subjected to MD simulation studies for 100 ns supporting the stability of the docked complexes.
