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United States Department of Agriculture

Agricultural Research Service

Title: The Effect of the Phop/q Locus of Brucella Abortus on the Infectious Cycle in Mice

item Halling, Shirley
item Bricker, Betsy
item Vadheim, Kirsten - FOOD AND DRUG ADMINIST
item Carlson, James - IA STATE UNIVERSITY
item Cheville, Norman - IA STATE UNIVERSITY
item Brabec, Marek - IA STATE UNIVERSITY

Submitted to: International Meeting on New Approaches to Bacterial Vaccine Development
Publication Type: Abstract Only
Publication Acceptance Date: May 28, 1996
Publication Date: N/A

Technical Abstract: Salmonella typhimurium and Brucella abortus are both facultative intracellular parasites of macrophages. The phoP/phoQ regulon has been shown to be essential for full virulence of S.typhimurium. We cloned a homolog of phoP/phoQ of B. abortus and have analyzed the sequences and compared them to entries in GenBank. A B. abortus phoP/Q mutant was constructed by allelic exchange, previously, and was given to mice in order to study the effect of the phoP/Q loci on the course of infection. B. abortus S2308 and a phoP/Q mutant and a complemented phoP/Q mutant were injected into mice and the course of infection followed by determining the number of bacteria in the spleen. In the mouse model, the brucellae numbers risen the spleen until about day seven and then continue to fall for over a week. The numbers begin to increase again after about a month from infection and large numbers can be reached by after two months. The phoP/Q mutation did not greatly attenuate the mutant but the course of infection was significantly different when the mutation was complemented with a low copy number (10) plasmid containing the locus. The numbers of brucellae in the spleen rose similarily in all groups but the rate of decrease after seven days was only different for the complemented mutant. The complemented mutant persisted like the other strains but did not reach similar numbers in the spleen in 60 days.

Last Modified: 4/22/2015
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