Inhibition of biofilm formation by serum raised to the outer membrane protein A of Acinetobacter baumannii

BACKGROUND AND AIMBiofilm production is one of the various virulence factors of Acinetobacter baumannii that helps the organism resist stressful conditions and facilitates the development of intense infections and diverse resistance mechanisms. Biofilms allow A. baumannii to survive and spread in hospital environments by attaching to different surfaces, such as cerebrospinal fluid shunts, and vascular catheters. Outer membrane protein A (OmpA) is a prominent porin in the outer membrane of A. baumannii. This protein plays a crucial role in bacterial pathogenesis by contributing to biofilm formation, interaction with epithelial cells, induction of apoptosis, and inhibition of complement, and serves as a potential vaccine candidate against A. baumannii infections.MATERIALS AND METHODSWe expressed recombinant protein OmpA (rOmpA). Purification was achieved using imidazole gradient of Ni-NTA column chromatography and confirmed with SDS-PAGE. The protein concentration was determined via Bradford colorimetric method. The purified OmpA was injected to BALB/c mice, and serum antibody titer was assessed using indirect ELISA. A. baumannii strains were exposed to OmpA serum, resuspended, and incubated in ۹۶-well plates. Crystal violet staining and ELISA reader absorbance measurements followed after washing and decolorization with acetic acid.RESULTS AND DISCUSSIONThe protein expression and purification were confirmed by analyzing the SDS-PAGE gel, which showed the protein at the expected position (approximately ۳۸ kDa) and ensured correct protein folding. The indirect ELISA results indicated an increased antibody titer in immunized mice compared to the control group. When the serum was challenged with the bacteria, it was observed that the serum reduced biofilm production in both the standard and clinical strains of A. baumannii.CONCLUSIONThe recombinant OmpA protein induced a protective effect against A. baumannii in mice and prevented biofilm formation in strains of A. baumannii. OmpA is considered as a promising subunit vaccine candidate against A. baumannii infections

کلیدواژه ها:

Acinetobacter baumannii ، OmpA ، Biofilm formation ، Subunit vaccine