Preventing Acinetobacter baumannii infection through active and passive immunization

Cara N. Wilder, Ph.D.

Multidrug-Resistance -- A growing concern throughout the world

Within the last two decades, multidrug-resistant strains have emerged as a common cause of drug-resistant infection throughout the world, resulting in prolonged hospitalizatin and high mortality rates. ATCC understands the danger and growing concern behind the spread of these strains, and we would like to help support your research in this field. For the several weeks, we will highlight various emerging multidrug-resistant strains, and some of the current research being performed with these superbugs. For more information, on these strains, subscribe to our eNewsletter or visit our website at www.atcc.org.

 

Preventing Acinetobacter baumannii infection through active and passive immunization

Acinetobacter baumannii is an opportunistic pathogen typically associated with a wide variety of complications, including pneumonia, localized tissue infections, septicemia, and death. This bacterium commonly infects individuals with a compromised immune system, and has become a predominant cause of infection in intensive care units, healthcare settings, and combat zones.


Within the last two decades, multidrug-resistant strains of A. baumannii have emerged as a common cause of drug-resistant infection throughout the world, resulting in prolonged hospitalization, extensive healthcare cost, and high mortality rates despite treatment. More troubling is the recent evolution of clinical variants that are pan-drug resistant, demonstrating resistance to every FDA-approved antibiotic. In response to these concerns, government agencies and research laboratories have focused their efforts on the development of new strategies targeted toward the prevention and treatment of such infections.




A CDC microbiologist working with Acinetobacter baumannii.
Photo courtesy of James Gathany and CDC.

In one vaccine discovery program, Luo et al. used a screening mechanism to identify an antigenic target for the development of a candidate vaccine that provided both active and passive immunization against A. baumannii. Following the intravenous infection of mice, OmpA was identified as a potential antigenic target based on humoral immunodominance during infection. Upon the analysis of this outer membrane protein, it was found that OmpA was highly conserved among numerous clinical isolates and demonstrated minimal homology with the human proteome. Additionally, vaccination of immune-compromised mice with an emulsification of recombinant OmpA and aluminum hydroxide adjuvant induced high titers of anti-OmpA antibodies, and demonstrated improved survival and reduced bacterial burden in intravenously infected mice. The activity of anti-OmpA antibodies was further confirmed through passive transfer studies, which recapitulated protection. Overall, the results from this study indicate that recombinant OmpA is an effective immunogen and promising candidate for the development of a novel vaccine to prevent A. baumannii infections.


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