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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Polycations on Brucella Abortus and Acid Induction of Resistance of Brucellae to Polymyxin B

item Halling, Shirley

Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 8, 2001
Publication Date: N/A

Interpretive Summary: Brucellosis is a bacterial disease that results in economic losses due to reproductive failure of cattle and to undulant fever in man. The causative agent of bovine brucellosis is unusual in that it survives in macrophages, a blood cell that engulfs and destroys most infectious bacteria. Macrophages kill the bacteria by releasing acid and other toxic compounds in to the vacuole containing the infectious agent. The causative agent of this disease was found under acid conditions to increase its resistance to some of these compounds. This work adds to our understanding of mechanisms of bovine brucellosis and aids in the development of treatments and other to control measures that are not based on live vaccines.

Technical Abstract: Macrophages destroy bacteria by taking them up in phagosomes and releasing acid and other components including cations into the phagosomes. Acid was found to induce increased resistance of Brucella abortus 544 and B. abortus S19 but not the rough vaccine strain B. abortus RB51 to the polycation polymyxin B. The attenuated B. abortus S2308 BvrR and BvrS mutants, which are more sensitive to polymyxin B than their parental strain, could be induced as well. However, these mutants, unlike B. abortus S2308, were sensitive to another polycationic peptide, cecropin P1. Acid induction of resistance of Brucellae to polycations could be essential to their ability to survive and grow within macrophages.

Last Modified: 4/22/2015
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