Protectivity of a recombinant protein derived from a ۵×Loop۳ of Omp۳۴ against Acinetobacter baumannii in a murine sepsis model

BACKGROUND AND OBJECTIVESAcinetobacter baumannii is a globally recognized primary cause of infections acquired in hospitals. This bacterium, although considered a low-grade opportunistic pathogen, plays a crucial role in causing various types of infections such as ventilator-associated pneumonia, urinary tract infection, skin and wound infections, bacteremia, and meningitis. In light of the emergence of antibiotic-resistant strains, alternative treatment strategies like recombinant vaccines and specific antibodies have gained importance for combating these infectious bacteria. However, the effectiveness of tested bacterial surface antigens has been limited to providing partial protection. Hence, the development of polyvalent (multi-antigen) vaccines incorporating different antigens has become imperative to achieve a satisfactory level of protection. In this study, the focus is on utilizing two outer membrane proteins, namely construct L۳x۵ and Omp۳۴, as components of a polyvalent vaccine.MATERIALS AND METHODSIt includes plasmid purification, expression, purification, and injection of construct L۳x۵ and Omp۳۴ recombinant proteins into BALB/c mice. Both active and passive immunizations were performed. The mice were subsequently challenged with a clinical isolate of A. baumannii. The antibody levels in mice were measured using Indirect ELISA. The survival rate of the challenged animals was also determined.RESULTS AND DISCUSSIONELISA analysis revealed increased antibody production in all immunized groups. However, the combined administration of the L۳x۵ construct and Omp۳۴ proteins provided superior protection compared to administering each protein individually.CONCLUSIONPolyvalent vaccines containing multiple antigens offer a satisfactory level of protection