Design and computational evaluation of a cross-protective multi-epitope vaccine candidate against Bartonella henselae and Bartonella clarridgeiae pathogens causing the zoonotic cat scratch disease in humans.

Cat scratch disease (CSD), primarily caused by Bartonella henselae and Bartonella clarridgeiae, presents a global zoonotic concern, particularly in immunocompromised individuals. Conventional antibiotics offer limited protection, necessitating novel preventive strategies. Also, CSD is still one of the most prevalent infections brought on by Bartonella genus. The current study aimed at developing a multi-epitope peptide vaccine by targeting conserved antigenic proteins (Pap31, Omp43, and Omp89) from two Bartonella species utilizing immunoinformatics techniques. Comprehensive immunoinformatics analyses including antigenicity, allergenicity, solubility, and post-translational modification assessments were conducted. The selected epitopes with high antigenicity and non-allergenic, non-toxic properties were fused using appropriate linkers and an adjuvant. The vaccine construct was modeled in 3D, refined, and validated via Ramachandran and ERRAT analyses. Molecular docking followed by molecular dynamics simulations demonstrated strong interaction and structural stability with TLR2 receptor in a mimicked biological environment. Moreover, immune simulations showed strong stimulation of B and T cell responses, elevated IgM and IgG levels, and increased IFN-γ production. These preliminary in silico findings suggest a promising multi-epitope peptide vaccine candidate with a cross-protective potential against both B. henselae and B. clarridgeiae pathogens causing the zoonotic cat scratch disease in humans.