In Silico Study on Immunogenicity of L۳Omp۳۴-L۳OmpA and L۳OmpA-L۷BauA Constructs on LCL Scaffold against Acinetobacter baumannii

BACKGROUND AND OBJECTIVESAcinetobacter baumannii is a challenging Gram-negative pathogen known for causing difficult-to-treat infections. Vaccination offers the best defense against these infections, and selecting biologically vital proteins can enhance the efficacy of a multi-antigen recombinant vaccine. This study aimed to design optimized structures using selected OMP epitopes to improve the immune response against A. baumannii.MATERIALS AND METHODSThe loop-free portion of the C lobe of the TbpB protein from Neisseria meningitidis M۹۸۲, known as LCL, was utilized as a scaffold to display conserved and exposed regions of A. baumannii OMP epitopes. Two combined structures, L۳Omp۳۴-L۳OmpA and L۳OmpA-L۷BauA, were constructed using Loop۳OmpA, Loop۳Omp۳۴, and Loop۷BauA. Bioinformatics tools were employed to analyze various aspects of the constructs, including B-cell epitope prediction, antigenicity, secondary structure prediction, ۳D modeling, and toxicity assessment.RESULTS AND DISCUSSIONThe L۳Omp۳۴-L۳OmpA and L۳OmpA-L۷BauA constructs exhibited promising characteristics. BepiPred۲ predicted ۱۰۰% and ۹۴.۵% linear B-cell epitopes, while Jpred۴ indicated that ۱۰۰% and ۹۰% of epitopes were coiled. I-TASSER modeling revealed that ۸۹% and ۱۰۰% of selected loops were exposed on the construct's surface. The regions selected by VaxiJen were predicted to be antigenic. Although the constructs were potentially insoluble, as predicted by biotech software, the ToxinPred server indicated that they were non-toxic.CONCLUSIONBased on the results, the L۳Omp۳۴-L۳OmpA and L۳OmpA-L۷BauA recombinant constructs show promise in enhancing immunoprotection against A. baumannii infections. These constructs hold potential as vaccine candidates for combating A. baumannii and warrant further investigation and experimental validation.