Novel computational One-Health analysis of fibrinogen-binding protein A in Streptococcus agalactiae Isolated from fish and human cases

Background and Aim: Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a zoonotic pathogen implicated in severe infections in humans and aquatic animals, particularly fish. Recent outbreaks of GBS sequence type 283 in Southeast Asia, associated with raw fish consumption, have raised public health concerns. Despite growing evidence of zoonotic transmission, comparative studies investigating virulence factor homology across hosts remain limited. This study focuses on the fibrinogen-binding protein A (FbsA), a critical virulence determinant in GBS pathogenesis. This study aimed to conduct a novel computational One Health analysis comparing the FbsA protein from fish- and human-derived GBS strains to elucidate their structural and functional similarities and explore their interaction with human fibrinogen (Fg). Materials and Methods: Amino acid sequences of FbsA from fish and human GBS isolates were retrieved from the National Center for Biotechnology Information database. Sequence alignment was performed using the MUSCLE algorithm in Molecular Evolutionary Genetics Analysis (MEGA) software. Three-dimensional structures were predicted through ColabFold and validated using Ramachandran plots. Residue profiling and structural visualization were conducted in PyMOL. Molecular docking between FbsA and Aα (G), Bβ (H), and γ (I) chains of human Fg was performed using ClusPro, followed by interaction analysis using LigPlot+. Results: Sequence alignment revealed 100% identity between fish and human-derived FbsA, indicating a conserved evolutionary relationship. The refined FbsA structure demonstrated α-helices and random coils with six repetitive regions. Molecular docking confirmed robust binding between FbsA and the D fragment of human Fg, involving key critical residues within the repetitive region (residues 45th–60th). Notably, interaction sites also included the β119–129 regions, overlapping with the plasmin cleavage site, potentially contributing to endocarditis and septicemia pathogenesis. Conclusion: The structural and functional equivalence of fish- and human-derived FbsA underscores the zoonotic risk of GBS transmission. These findings offer a compelling foundation for targeted vaccine development and preventative strategies to mitigate GBS infections across species boundaries. Keywords: fibrinogen-binding protein A, fish-to-human transmission, in silico analysis, molecular docking, One Health, Streptococcus agalactiae, zoonosis.