Protection against Acinetobacter baumannii infection via its functional deprivation of biofilm associated protein (Bap)

Immunological evaluation of OMV(PagL)+Bap(1-487aa) and AbOmpA(8-346aa)+Bap(1-487aa) as vaccine candidates against Acinetobacter baumannii sepsis infection

“…In silico analyses showed four immunodominant conserved regions from Bap sequence of A. baumannii which have high potential for triggering antibodies against this protein (Rahbar et al, 2010). Experimental data demonstrated mice immunized to Bap subunit had high antibody titer and low bacterial loads in their spleen after challenge (Fattahian et al, 2011). These studies offer immunodominant regions of Bap protein have appropriate characteristics for being one of the vaccine candidates.…”

Physiology and Pathology of Multidrug-Resistant Bacteria: Antibodies- and Vaccines-Based Pathogen-Specific Targeting

“…Bap, containing seven tandem repeats of modules, is 41-66% conserved among clinical isolates and its expression is induced by low iron concentration [177,178]. Immunization of mice with one region of Bap from A. baumannii elicited protective immunity against A. baumannii of diferent strains, suggesting that Bap is conserved and can be used as a potential vaccine candidate [179].…”

Identification of novel vaccine candidates againstAcinetobacter baumanniiusing reverse vaccinology

“…37 A. baumannii secretes OMVs which interact with host cells and then deliver bacterial effectors contributing to bacterial pathogenesis and immunopathology. 12 To enhance the power of reverse vaccinology, we also integrated functional genomics and proteomic analysis using bioinformatics tools to further refine the screening criteria for protective antigens. We (results to be published elsewhere) and others [17][18]25,28 used HPLC-MS/MS to analyze the proteomic profiles of OMVs and identified 65 potential antigens from A. baumannii ATCC17978 strains (Table S1).…”

“…They include outer membrane vesicles (OMVs), outer membrane protein A (OmpA), auto-transporter (Ata), biofilm-associated protein (Bap), K1 capsular polysaccharide and Poly-N-acetyl-b-(1-6)-glucosamine (PNAG). [7][8][9][10][11][12][13][14] The sequence variability of these antigens and their absence in the circulating Ab strains may result poor cross-protective efficacy against HAI caused by new emerging Ab strains that may possibly mutate under selective immunological pressure and down-regulate the target antigens. In our hand, recombinant OmpA and a truncated fragment of Bap have been tested and found no protection in mouse pneumonia challenge studies; only inactivated Ab and/or PNAG-protein conjugate showed good protection in the mouse pneumonia challenge model (Chong et al, unpunished results).…”

“…In order to identify novel antigens; we excluded proteins which had been tested and found to be not protective in our hands. Our current approach may have failed to identify potential vaccine immunogens, such as biofilm associated protein (Bap, ABAYE0792), 12 trimeric autotranspoter (Ata), 11 and other unknown putative proteins that could play critical role in A. baumannii pathogenesis. In addition, a limitation in our approach is the fact that immuno-proteomic data could be influenced by different culture conditions such as growing the pathogen in clinically relevant media reflecting the infection environment.…”