The Outer Membrane Proteins and Their Synergy Triggered the Protective Effects against Pathogenic Escherichia coli

Abstract

Colibacillosis caused by pathogenic Escherichia coli (E. coli) is one of the most serious infectious diseases, causing an extensive burden on animal husbandry and the human healthcare system. Vaccination is one of the ideal ways to prevent E. coli infection. In this work, recombinant outer membrane protein A (rOmpA), outer membrane protein C (rOmpC) and BamA (rBamA) from E. coli O78 (CVCC CAU0768) were expressed in a prokaryotic expression system with the concentration of 1–2 mg/mL after purification. Considerable immune responses could be triggered in mice that were immunized with these recombinant proteins, high antibody titers, high total IgG level and various antibody isotypes were detected in antisera after booster immunizations. Moreover, mice immunized with several recombinant proteins in combination showed a higher survival rate with the challenge of homologous strain E. coli O78 and a more significant cross-protection effect against heterologous strain E. coli O157: H7 (CICC 21530) in vivo than those of immunized alone. The antisera from immunized mice showed high affinity to multiple strains of Escherichia, Shigella and Salmonella in vitro, indicating that recombinant outer membrane proteins from E. coli O78 had the potential to be developed into universal antigenic substances against not only E. coli but also a variety of Gram-negative bacteria. rOmpA was considered as the most immunogenic protein in this work and the combination of different proteins could further enhance the immune response of immunized mice, which provided the reference for the construction of novel antigens with higher efficiency.

Characterization of Three New Outer Membrane Adhesion Proteins in Fusobacterium necrophorum

“…Alternatively, it is possible that the concentration of antibodies in sera used for our in vitro experiments was insufficient for neutralization. In a study using OMPs as a subunit vaccine in E. coli O78, three outer membrane proteins in combination were used for immunization, which resulted in higher immunogenicity [53]. Future in vivo studies are therefore needed to elucidate the precise functions of these conserved OMPs and determine whether they have the potential for vaccine development, as demonstrated in other pathogenic bacteria.…”

Novel Proteoliposome-Based Vaccine against E. coli: A Potential New Tool for the Control of Bovine Mastitis

“…The proteoliposomes were able to retain several bacterial macromolecules with immunostimulatory potential, particularly membrane proteins, DNA and LPS. In SDS-PAGE gels, the presence of quantitatively important bands located between 35–45 kDa suggests the retention of highly antigenic outer membrane porins (Omp) [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. In addition, highly similar protein electrophoretic patterns in polyacrylamide gels were observed during the production process of E. coli proteoliposomes ( Supplementary Figure S1 ), suggesting that proteins retained in proteoliposomes are not denatured during production, contrary to formaldehyde treatment, which alters the chemical structure of proteins, induces protein crosslinking, limiting antigenic processing by APCs and, therefore, restricting antigenic presentation to T cells and the generation of memory cells [ 22 , 23 , 24 ].…”