In silico study of the immunogenicity of a construct containingthe extracellular loops of Acinetobacter baumannii outermembraneproteins exposed on the LCL platform

Background and Aim : Acinetobacter baumannii has recently emerged as an importantnosocomial pathogen that causes infections, especially in immunocompromised patients. In thiscontext, introducing an effective vaccine for the prevention of infections caused by this bacteriumas a cost-effective seems necessary. Therefore, this study aimed to design the best structurecombined with three selected loops of OMP epitopes based on their properties to improve immuneresponse against A. baumannii.Methods : In this study, LCL (Loopless C-lobe) was used as a scaffold to display three surfaceexposed and conserved regions of OMPs epitopes including Loop۳OmpA, Loop۳Omp۳۴, andLoop۷BauA. In the next step, different bioinformatics tools were used to analyse this constructfrom different aspects such as BepiPred۲ that predicts the location of linear B-cell epitopes,probability of antigenicity was predicted for selected regions using Vaxijen server(Threshold=۰.۴), Jpred۴ used to predict three-state (a-helix, b-strand and coil) secondary structurewith accuracy of >۸۰.۰%, ۳D structures of the selected regions were predicted by I-TASSERserver, and ToxinPred server used to identify highly toxic or non-toxic peptides.Results : The Bepipred۲ server predicted ۹۶% linear B-cell epitopes in this construct. The regionsselected by the VaxiJen server were predicted as an antigen. The results of the prediction of thesecondary structure by the Jpred۴ server showed that ۹۸% of epitopes are coiled. The results of ITASSERmodeling showed that ۹۶% of selected loops are exposed at the surface of the construct.This construct was probably not soluble as predicted by biotech software. Finally, according to theToxinPred server results, the designed construct is predicted to be non-toxic.Conclusion : According to obtained results, this construct can increase the function of theimmunogenic epitopes and so this combination could be suggested as an appropriate vaccinecandidate against A. baumannii.

Keywords:

Acinetobacter baumannii , bioinformatic , OmpA , Omp۳۴ , Loop۷BauA , vaccine