Abstract
Background:
In-silico analysis and molecular docking tools offer alternative ploy to characterize the virulence factors of Edwardsiella tarda and identify potential herbal antimicrobial compounds as substitutes to overcome the adverse health effects of antibiotics.
Aim:
In this study, fimbrial adhesion proteins of E. tarda namely etfB and etfC were regarded as virulence factors for bioinformatic analysis.
Methods:
The virulent protein sequences, recovered from the UniProt database, were analyzed structurally and functionally. SWISS-MODEL generated the homology models of these proteins and verified the quality. The predicted 3D models were used as receptors individually in docking studies against select herbal compounds as ligands for these proteins.
Results:
Both proteins were soluble, hydrophobic and thermally stable. The predicted models’ Z-values were within the scores particularly found for native proteins of the same size, indicating that the models were suitable. The molecular docking identified corilagin (Terminalia chebula), lutein (Amaranthus viridis), isoginkgetin (Cyperus rotundus), amentoflavone (Cyperus rotundus) and acacic acid (Acacia concinna) as the best herbal compounds against etfB gene, and sciadopitysin (Cyperus rotundus), oleandrin (Nerium oleander), isoginkgetin (Cyperus rotundus), ginkgetin (Cyperus rotundus) and cyanidin 3- sophoroside (Hibiscus rosa-sinensis) against etfC gene based on the lowest E-values in order.
Conclusion:
This study revealed that the fimbrial proteins are potential drug targets. Docking results predicted that these low E-value herbal compounds may control edwardsiellosis in aquaculture, which can be further validated using in vitro and in vivo studies. The bioinformatics tools save time, cost and energy in finding promising drugs against a specific target of interest.

Key words: Edwardsiellosis, Edwardsiella tarda, Virulence proteins, Herbal compounds, Molecular docking