Antigenic Properties of Iron Regulated Proteins in Acinetobacter baumannii: An In Silico Approach

Acinetobacter baumannii, an emerging nosocomial pathogen, causes multi-drug and pan-drug resistant infections. This phenomenon necessitates the development of new treatment strategies or vaccines against this pathogen. Iron acquisition systems are important factors for the virulence of pathogenic organisms. Antibodies against iron regulated outer membrane proteins (IROMPs) showed bactericidal and opsonizing activities against A. baumannii in vitro. Data obtained from proteomic studies could be valuable for vaccine design. Comparative proteomic analysis of total lysate and outer membrane fractions isolated from A. baumannii ATCC 19606 cells cultured under iron-rich and chelated conditions resulted in the identification of protein spots differentially produced. Need for bioinformatic tools is imperative for analysis of these data as well as to design novel proteins bearing desired properties. This study undertakes in silico identification of the most effective immunogenic target amongst these iron regulated proteins in A. baumannii which can be employed as a vaccine candidate. Here a screening was carried out on iron- regulated A. baumannii OMPs, based on hydrophilicity, flexibility, beta-turns, solubility and overall antigenic probability. 3D structure of the proteins was modeled. Linear and conformational B cell epitopes predicted and their densities were used for comparison of their immunogenicity. CarO was selected as an efficient immunogenic IROMP in A. baumannii which contributes to sidrophore mediated iron uptake.