Engineering a multi-epitope chimera derived from Acinetobacter baumannii CAM87009.1 and FilF fimbriae proteins: immunogenic and antibiofilm activity.

This study aimed to develop a multi-epitope recombinant chimera (rChimera) based on two outer membrane proteins of Acinetobacter baumannii, targeting passive or active immunization strategies against biofilm-forming strains of this multidrug-resistant bacterium. Using bioinformatics and reverse vaccinology, we identified CAM87009.1 and FilF as two conserved proteins involved in biofilm formation and host cell adherence. An in silico analysis was performed to design the rChimera, selecting 36 promising B- and T-cell epitopes, including those recognized by MHC class I and II. These epitopes were linked using a glycine linker (GGGG) and a rigid linker (EAAKEAAAKA). The chimera was chemically synthesized, successfully expressed in Escherichia coli BL21 Star, and recognized by antibodies from naturally infected patients. Polyclonal antibodies (pAbs) produced in a murine model elicited a significant IgG response from the 14th day after the first immunization, with IgG1 and IgG2 (a and b) being the predominant isotypes generated. Anti-rChimera pAbs effectively inhibited biofilm formation in multidrug-resistant isolates and the ATCC® 19,606 strain of A. baumannii. The recombinant chimera shows promise for passive or active immunization against biofilm-forming strains of A. baumannii.