ABSTRACT
Acinetobacter baumannii [A. baumannii] is a major hospital pathogen with a high capacity to resist most common anti-microbial agents. A. baumannii is the etiologic agent for various illnesses including pneumonia, meningitis, and bloodstream infections. Biofilm associated proteins [Bap] are specific cell surface proteins essential for the formation of biofilm and play a main role in its pathogenicity. Previously, we have studied various regions of this protein. Considering different criteria, some regions were introduced as conserved and immunogenic. The immunogenicity of one of those regions pertaining to amino acids 706-1076 previously examined has shown that its expression triggers high antibody levels when injected to mice thereby protecting the animals against the bacterium. The present study examines region 4 of the Bap protein in order to validate the previous bioinformatics studies and its immunogenicity. In order to obtain immunity against this pathogen, a 1620 bp gene from Bap was amplified and cloned in pET32a. This region from Bap was cloned, expressed and verified by monoclonal antibodies. BALB/c mice were immunized by subcutaneous injection of the pure recombinant protein. Mice immune response was determined by ELISA. High titer of raised antibodies implied that the recombinant protein was a strong antigen and immunogen. The results indicate that this protein can be a suitable choice for developing a new recombinant vaccine against A. baumannii
ABSTRACT
Acinetobacter baumannii [A. baumannii] is a Gram-negative, non-motile aerobic bacterium which is known as a nosocomial pathogen that is often resistant to a broad range of antibiotics. The pathogen is a serious agent of mortality and morbidity in hospitals, particularly among immunocompromised patients. Treatment and control of its infections is complicated owing to its high antibiotic resistance, survival in various environmental conditions and utilization of wide range of nutrient sources. Early detection of the pathogen in established infections is pivotal for infection control. Culture and biochemical tests are current methods for detection of the bacterium, which take approximately 2-5 days. Hence, a new, rapid, specific and affordable diagnostic test is needed. Development of such test depends on a suitable biomarker that lacks crossreactivity with other bacteria. This study intends to unveil a 34.4 kDa outer membrane protein [OMP] introduced by Islam et al. in A. baumannii ATCC19606. We harnessed various bioinformatic servers to screen the entire proteome of this bacterium. Properties critical to the screening included molecular weight, localization, topology, homology, antigenicity and allergenicity of proteins. Three proteins were found as suitable candidate molecular weights as well as localization points of view. BLAST searches, antigen probability predictions and other analyses led to the selection of one protein as the best specific antigen of A. baumannii. The in silico analyses unveiled the best candidate protein vide accession number ZP_05827218.1