Anti-Omp34 antibodies protect against Acinetobacter baumannii in a murine sepsis model
Aleme Naghipour Erami1, Iraj Rasooli2, Abolfazl Jahangiri3
1Department of Biology, Shahed University, Tehran-Qom Express Way, Iran.
Abstract:
Acinetobacter baumannii, an opportunistic extracellular pathogen is one of the major causes of nosocomial infections. Omp34, also known as Omp33-36, is a bacterial porin protein involved in the virulence and fitness of this pathogen by adhesion to the host cell. This antigen nominated as an appropriate candidate for immunization against A. baumannii. In this study, the expression of the recombinant Omp34 (rOmp34) was carried out in E. coli BL21 (DE3). The immunogenicity of the rOmp34 in A. baumannii was studied in a murine sepsis model. Antibody response in mice injected with the recombinant protein was assessed using indirect ELISA. Bactericidal activity of rOmp34-immunized mice sera (1:10 dilution) against A. baumannii ATCC 19606 after 0, 1, 2, 4, and 8 h of incubation at 37 °C was assessed. In addition to survival rate, load of bacteria in liver and spleen of the infected mice were evaluated. A high titer of specific antibody equivalent to optical density of 1.54 ± 0.06 against rOmp34 was elicited in the immunized mice sera. Viability of the A. baumannii incubated 8 h with immunized mice sera was 64%. Homogenized liver and spleen samples of the control mice challenged with A. baumannii were loaded with 8 × 103 and 9 × 103 CFU per gram tissue respectively 48 h post-challenge as against complete clearance of A. baumannii in the immunized group. The protective immunity was achieved by challenging the mice groups with 5 × LD50 of live A. baumannii. Omp34 can be nominated as an immunogen that can bring about protection against Acinetobacter baumannii.
Insights
Recombinant Omp34 protein from Acinetobacter baumannii elicits a strong antibody response in mice, demonstrating significant protection against bacterial infection and reducing bacterial load in organs. This suggests Omp34 is a promising immunogen for Acinetobacter baumannii vaccines.
Area of Science:
- Microbiology
- Immunology
- Vaccine Development
Background:
- Acinetobacter baumannii is a significant cause of hospital-acquired infections.
- Omp34, a porin protein, plays a crucial role in A. baumannii virulence and host cell adhesion.
- Omp34 is a potential candidate antigen for immunization against A. baumannii.
Purpose of the Study:
- To express recombinant Omp34 (rOmp34) in E. coli.
- To evaluate the immunogenicity and protective efficacy of rOmp34 in a murine sepsis model.
- To assess the antibody response, bactericidal activity, survival rates, and bacterial load in immunized mice.
Main Methods:
- Recombinant Omp34 protein was expressed in E. coli BL21 (DE3).
- Immunogenicity was assessed via indirect ELISA in a murine model.
- Bactericidal activity, survival rates, and bacterial organ load were evaluated post-challenge with A. baumannii.
Main Results:
- High titers of specific antibodies against rOmp34 were observed in immunized mice.
- A. baumannii viability decreased significantly after incubation with immune sera (64% at 8 hours).
- Complete clearance of A. baumannii from liver and spleen was observed in immunized mice, with significantly improved survival rates.
Conclusions:
- Recombinant Omp34 elicits a robust immune response in mice.
- Omp34 demonstrates protective immunity against Acinetobacter baumannii infection.
- Omp34 is a viable candidate for developing vaccines against A. baumannii.
