Author
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Halling, Shirley |
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Submitted to: American Society of Microbiologists Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 5/2/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Brucellae are facultative intracellular pathogens and their infectious cycle is unique. Though much is known about the infectious cycle much is also unknown. Brucella abortus causes brucellosis in the bovine and can infect man secondarily causing undulant fever. Brucellae primarily infect cattle through the alimentary tract by crossing the lymphoepithelial tissue and being transported by professional phagocytes to various lymphoid tissues and milk. Though the neutrophiles are efficient at killing brucellae, brucellae survive in macrophages and are thought to persist in the reticuloendothelial system. Brucellae grow in both nonphagocytic and phagocytic cells. Brucellae in nonphagocytic cells such as Vero and in trophoblast cells grow to high numbers within the cisternae of the rough endoplasmic reticulum before these cell lysis. In macrophages, the brucellae grow in phagosomes and reduce phagolysosome fusion. When phagosomes kill bacteria, an early step is the acidification of the lysosome. Recently, it was reported that acid sensitive brucellae mutants are attenuated. Recombinant DNA technology is being used to determine the genetic basis of pathogenicity of brucellae. Genes encoding RecA, the protease Lon, HtrA, Cu-Zn superoxide dismutase, an immunogenic 31 kilo-dalton protein and PurE have been knocked out by various laboratories, and the virulence of these mutants has been analysed in mice and/or macrophages. Some differences were observed in the infectious cycle of some of these mutants. |
