In silico evaluation, cloning, and expression of Omp۲۲ as a promising vaccine candidate against Acinetobacter baumanii

BACKGROUND AND ABJECTIVEThe prevention and control of infections still heavily rely on prophylactic strategies such as vaccination. Recently, Omp۲۲ from A. baumannii has been identified as an effective vaccine candidate. However, limited data is available about this protein. This study aimed to comprehensively in silico analyze of Omp۲۲ and its expression in vitro.MATERIALS AND METHODSThe sequence of Omp۲۲ was retrieved and then scanned for subcellular localization, antigenicity, allergenicity, homology to human proteome, physiochemical characteristics, linear and conformational B-cell epitopes, MHC binding sites, tertiary structure prediction, and molecular dockings. Additionally, the gene encoding omp۲۲ was cloned into the pET-۲۸a (+) vector and the expression level was optimized.RESULTS AND DISCUSSIONThe results showed that Omp۲۲ has a molecular weight of ۲۲.۴۸ kDa, pI of ۹.۳۰, and belongs to the outer membrane proteins superfamily without transmembrane helices. Omp۲۲ was confirmed as non-allergen with appropriate stability. Two linear B-cell epitopes were identified, as well as ۱۰۸ MHC-I and ۵۰ MHC-II binding sites, that could help to develop an epitope-based vaccine. Three conformational B-cell epitopes were identified through ۳D structure prediction, and molecular docking analysis showed desirable interactions in the docked complexes. The optimized expression of the recombinant Omp۲۲ was successfully achieved with ۰.۵ mM IPTG for ۴h incubation at ۳۷°C. This result can facilitate further investigations on Omp۲۲-based subunit vaccines.CONCLUSIONThis study represents a significant step towards developing an Omp۲۲-based vaccine candidate against A. baumannii. However, further experimental analyses are still needed.

کلیدواژه ها:

Acinetobacter baumannii ، Omp۲۲ ، Vaccine ، In silico study ، Expression