In-Silico Design and Assessment of Epitope-Based Vaccine to Thwart the Infections Caused by Acinetobacter baumannii

Abstract

Gram-negative, opportunist pathogen Acinetobacter baumannii is notorious for causing a plethora of nosocomial infections predominantly including respiratory diseases and blood-stream infections. Moreover, numerous scientific reports have described it as the foremost cause for the spread of multi-drug resistant bacteremia. In the event of resistance development towards last- resort antibiotics, its treatment has become almost impossible due to the sweeping decline in the availability of therapeutic possibilities. Despite numerous vaccine candidates being proposed, no marketable vaccine for this ubiquitous pathogen is available. It is therefore apropos to formulate a rational vaccine plan to get rid of the super-bug. Taking into account the importance of Outer Membrane Porin D (OprD) as a potential vaccine candidate, we methodically combined the most persistent epitopes present in the A.baumannii strains with the help of different immunoinformatic approaches to envisage a systematic multi-epitope vaccine design. The proposed vaccine contains non-cytotoxic and highly immunogenic stretches of linear B-cells, Cytotoxic T Lymphocyte epitopes, and Helper T Lymphocyte epitopes of outer membrane porin. The finalized epitopes proved to be significant as they are conserved in MDR A.baumannii strains. The final 3-D structure of the construct was projected, refined, and verified by employing several in-silico approaches. Apt binding of the protein and adjuvant with the TLR4 suggested appropriate docking of the molecules. Immune simulations suggested a prominent increase in the levels of the immune response. The proposed vaccine model is suggested to be thermostable, immunogenic, water- soluble, and non-allergenic.