<i>Brucella abortus</i>
            Genes Identified following Constitutive Growth and Macrophage Infection

Eskra, Linda; Canavessi, Áurea Maria Oliveira; Carey, Merriann; Splitter, Gary A.

doi:10.1128/iai.69.12.7736-7742.2001

Cited by 78 publications

(67 citation statements)

References 43 publications

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“…A number of recent studies have reported the virulence genes of Brucella (Drazek et al, 1995;Endley et al, 2001;Eskra et al, 2001;Foulongne et al, 1999). The VirB type IV secretion system of Brucella has been identified recently Sieira et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

Roles of Brucella abortus SpoT in morphological differentiation and intramacrophagic replication

et al. 2005

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The essential mechanisms and virulence factors enabling Brucella species to survive and replicate inside host macrophages are not fully understood. The authors previously reported that a putative guanosine 59-diphosphate 39-diphosphate (ppGpp) mutant (spoT mutant) of Brucella abortus failed to replicate in HeLa cells. The present study showed that the pattern of surface proteins and morphological change of the spoT mutant were different from B. abortus wild-type. B. abortus wild-type changed its morphology upon treatment with ppGpp synthetase I activation inhibitor. In various tests under stress conditions, including nutrient starvation, nitric oxide resistance, acid resistance and antibiotic resistance, the spoT mutant had a lower stress resistance than B. abortus wild-type. Although the spoT mutant has the same smooth phenotype and LPS profile as B. abortus wild-type, it had a higher rate of adherence to macrophages but lower internalization and intracellular replication within macrophages. The spoT mutant did not co-localize with either late endosomes or lysosomes and was almost cleared from the spleens of mice after 10 days, without splenomegaly. RT-PCR was used to detect spoT mRNA from around 10 6 cells incubated in low-pH enriched medium; it showed that the expression of spoT increased after 30 min incubation. The data suggest that SpoT does not contribute to intracellular trafficking of B. abortus, but contributes to the maintenance of bacterial morphology and the physiological adaptation required for intracellular replication. INTRODUCTIONBrucellosis is a major bacterial zoonosis and an important cause of a serious debilitating disease in humans and abortion and sterility in domestic animals. This disease is caused by species of the genus Brucella, classified in the a2 subdivision of Proteobacteria, small Gram-negative and facultative intracellular pathogens that can multiply within professional and non-professional phagocytes (Delrue et al., 2001;Detileux et al., 1990). The genus Brucella consists of seven species according to antigenic variation and primary host: B. melitensis (sheep and goats), B. suis (hogs), B. abortus (cattle), B. ovis (sheep), B. canis (dogs), B. neotomae (wood rats) and B. maris (marine mammals) (Ko & Splitter, 2003). In contrast to other intracellular pathogens, Brucella species do not produce exotoxins, antiphagocytic capsules, thick cell walls, resistance forms or fimbriae and do not show antigenic variation (Finlay & Falkow, 1997).A key aspect of the virulence of Brucella species is their ability to proliferate within professional and nonprofessional phagocytic host cells, therefore successfully bypassing the bactericidal effects of phagocytes. Their virulence and chronic infections are thought to be due to their ability to avoid the killing mechanisms within host cells (Comerci et al., 2001;Ugalde, 1999). Neither virulence factors that allow intracellular survival of Brucella species nor the specific factors that induce such virulence have been elucidated. B. abortus is inte...

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Section: Discussionmentioning

confidence: 99%

Roles of Brucella abortus SpoT in morphological differentiation and intramacrophagic replication

et al. 2005

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“…Expression studies using a GFP reporter system revealed that the B. abortus dxs gene was activated during survival within RAW macrophages. The authors of that study proposed that the expression of this gene leads to the accumulation of antioxidants (produced via the MEP pathway), which allows for initial survival in the oxidative environment within the phagosome of the macrophage (Eskra et al, 2001).…”

Section: Virulence Potentialmentioning

confidence: 99%

Isoprenoid biosynthesis in bacterial pathogens

et al. 2012

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“…inside the macrophage is a prerequisite to the understanding of the relation with the macrophage. Signature-tagged mutagenesis and differential fluorescence induction approaches were recently used to identify genes required for virulence in a murine model of infection and in human and murine macrophages (5)(6)(7)(8)(9). A large proportion of these genes encode enzymes of various metabolic pathways.…”

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confidence: 99%

The analysis of the intramacrophagic virulome ofBrucella suisdeciphers the environment encountered by the pathogen inside the macrophage host cell

Köhler

Foulongne

Ouahrani‐Bettache

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

229

232

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The pathogen Brucella suis resides and multiplies within a phagocytic vacuole of its host cell, the macrophage. The resulting complex relationship has been investigated by the analysis of the set of genes required for virulence, which we call intramacrophagic virulome. Ten thousand two hundred and seventy-two miniTn5 mutants of B. suis constitutively expressing gfp were screened by fluorescence microscopy for lack of intracellular multiplication in human macrophages. One hundred thirty-one such mutants affected in 59 different genes could be isolated, and a function was ascribed to 53 of them. We identified genes involved in (i) global adaptation to the intracellular environment, (ii) amino acid, and (iii) nucleotide synthesis, (iv) sugar metabolism, (v) oxidoreduction, (vi) nitrogen metabolism, (vii) regulation, (viii) disulphide bond formation, and (ix) lipopolysaccharide biosynthesis. Results led to the conclusion that the replicative compartment of B. suis is poor in nutrients and characterized by low oxygen tension, and that nitrate may be used for anaerobic respiration. Intramacrophagic virulome analysis hence allowed the description of the nature of the replicative vacuole of the pathogen in the macrophage and extended our understanding of the niche in which B. suis resides. We propose calling this specific compartment ''brucellosome.'' I nteractions between microorganisms and their hosts extend from acute infections to persistent infectious diseases or symbiosis. This type of interaction can result from a million years of coevolution and coadaptation of the two organisms. Thus, the biology of the interaction can be read, at least partially, in the genome of the microorganism. In the specific case of pathogenic bacteria, deciphering of the genes involved in the interaction and analysis of their functions will shed light on the environment encountered by the parasite in the host and will contribute to the understanding of the complex relationship between two organisms. As a name for the whole set of genes required for virulence, i.e., involved in the invasion of the host by the bacteria and their adaptation to the environment provided by this host, we propose virulome. In this study, we will perform a thorough analysis of the intramacrophagic virulome of Brucella suis.Brucella spp. is an ␣ proteobacteriaceae that induces a persistent disease in some mammals, resulting in abortion. In humans, initial septicemia may be followed by a subacute or a chronic infection (1). Brucella spp. is phyletically related as well to plant symbionts such as rhizobiaceae, as to rickettsiae, which generate an acute infectious disease (2). In terms of virulence, brucellae occupy an intermediate position where the adaptation results in a mild disease that allows them to persist in mammal hosts. It is usually considered that, for a facultative intracellular bacterium such as Brucella spp., which multiplies in trophoblasts or macrophages (3), one of the challenges is to rapidly adapt to the intracellular settings but also to resis...

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Brucella abortus Genes Identified following Constitutive Growth and Macrophage Infection

Cited by 78 publications

References 43 publications

Roles of Brucella abortus SpoT in morphological differentiation and intramacrophagic replication

Roles of Brucella abortus SpoT in morphological differentiation and intramacrophagic replication

Isoprenoid biosynthesis in bacterial pathogens

The analysis of the intramacrophagic virulome ofBrucella suisdeciphers the environment encountered by the pathogen inside the macrophage host cell

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