Introduction: Acinetobacter baumannii is the most important agent of hospital-acquired infections worldwide. This bacterium has been regarded as a low-grade but an important opportunistic pathogen that causes various types of infections, including ventilator-associated pneumonia, urinary tract infection, skin and wound infections, bacteremia, and meningitis. Recombinant vaccines and specific antibodies are a new treatment strategies for such antibiotic-resistant infectious bacteria. However, a small number of bacterial surface antigens were tested that could only provide partial protection. For this reason, polyvalent (multiple) vaccines containing different antigens are needed to provide an acceptable level of protection. This study is oriented on the use of two outer membrane proteins, BauA and Omp34 as a polyvalent vaccine.
Methods: Recombinant BauA and Omp34 proteins were expressed, purified, and injected into BALB/c mice individually and in combination. Both active and passive immunizations were carried out. The mice were then challenged with a clinical isolate of A.baumannii. Then, the level of antibody in mice was measured by Indirect ELISA. The animal survival rate was also determined.
Results: Elevated antibody production was noted by ELISA in all the immunized groups. The combination of BauA and Omp34 proteins rendered good protection compared to the single administration of each protein
Conclusion: These data indicate that antibodies to protein antigens can boost immunity and protection against A. baumannii strains. The findings are supporting use of multivalent monoclonal antibody therapy to control infections caused by A. baumannii. We can therefore suggest the designed hybrid antigens as novel immunogenic candidates for developing effective subunit vaccine against A. baumannii infection