Mechanism of serum resistance among Brucella abortus isolates

Eisenschenk, Frank C.; Houle, J.J.; Hoffmann, Edward M.

doi:10.1016/s0378-1135(99)00075-9

Cited by 32 publications

(24 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…abortus is due to effects of the classical and not the alternative pathway (9,13,22,23). In addition, our results provide evidence for the first time that MBL may also play a role in host defense against Brucella.…”

Section: Vol 69 2001mentioning

confidence: 57%

“…Although differences in susceptibility to serum between these two species (17,58) and the role of O antigen in the resistance of Brucella to complement-mediated killing have been reported previously, most of these studies have been done using fortuitously isolated rough variants (9,12,13,36). More recent work with genetically defined rough mutants has focused on understanding the effect of alterations in the synthesis of OPS on Brucella virulence, i.e., survival in macrophages and mice, but little or no information on the interactions of complement with these strains is available (3,19,29,36,55).…”

Section: Discussionmentioning

confidence: 99%

“…Although the genus Brucella is highly homogeneous at the DNA level (52), major differences and diversity among Brucella species are found in the major OMP. OMP are exposed on the bacterial surface but are less accessible to complement in smooth strains than in rough strains (8,13,31,32). Both the OPS length and the proportion of S-LPS on the bacterial surface influence the ability to shield bacteria from complement-mediated killing (4,31,32).…”

Section: Vol 69 2001mentioning

confidence: 99%

“…Previous studies using bovine serum (17) and NHS (58) have suggested that B. melitensis is more resistant than B. abortus to the bactericidal action of complement, although the mechanisms of this enhanced resistance are unknown. Smooth strains of B. abortus are more resistant than rough strains to serum bactericidal activity (9,12,13). Although this difference has plausibly been attributed to the lack of surface OPS in rough strains, the strains used in these studies were not genetically characterized, and the contribution of other components beside OPS to the resistance of smooth strains could not be rigorously excluded.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Deletion ofwboAEnhances Activation of the Lectin Pathway of Complement inBrucella abortusandBrucella melitensis

et al. 2001

View full text Add to dashboard Cite

Brucella spp. are gram-negative intracellular pathogens that survive and multiply within phagocytic cells of their hosts. Smooth organisms present O polysaccharides (OPS) on their surface. These OPS help the bacteria avoid the bactericidal action of serum. The wboA gene, coding for the enzyme glycosyltransferase, is essential for the synthesis of O chain in Brucella. In this study, the sensitivity to serum of smooth, virulent Brucella melitensis 16M and B. abortus 2308, rough wboA mutants VTRM1, RA1, and WRR51 derived from these two Brucella species, and the B. abortus vaccine strain RB51 was assayed using normal nonimmune human serum (NHS). The deposition of complement components and mannose-binding lectin (MBL) on the bacterial surface was detected by flow cytometry. Rough B. abortus mutants were more sensitive to the bactericidal action of NHS than were rough B. melitensis mutants. Complement components were deposited on smooth strains at a slower rate compared to rough strains. Deposition of iC3b and C5b-9 and bacterial killing occurred when bacteria were treated with C1q-depleted, but not with C2-depleted serum or NHS in the presence of Mg-EGTA. These results indicate that (i) OPS-deficient strains derived from B. melitensis 16M are more resistant to the bactericidal action of NHS than OPS-deficient strains derived from B. abortus 2308, (ii) both the classical and the MBL-mediated pathways are involved in complement deposition and complement-mediated killing of Brucella, and (iii) the alternative pathway is not activated by smooth or rough brucellae.

show abstract

Section: Vol 69 2001mentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Vol 69 2001mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Deletion ofwboAEnhances Activation of the Lectin Pathway of Complement inBrucella abortusandBrucella melitensis

et al. 2001

View full text Add to dashboard Cite

show abstract

“…C1q or the C1 complex has been reported to bind to several candidate molecules on Gram-negative bacteria. These include porins or outer membrane proteins from Aeromonas, Klebsiella, Salmonella and Brucella species (Latsch et al, 1992;Albertí et al, 1996;Eisenschenk et al, 1999;Merino et al, 2005) as well as lipid A and LPS components such as polyribosyl-ribitolphosphate from Haemophilus influenzae (Bunse and Heinz, 1993). Other reports indicate other modes of C1q binding via its collagen region, in a manner which does not activate the classical pathway.…”

Section: Discussionmentioning

confidence: 99%

Interactions of complement proteins C1q and factor H with lipid A and Escherichia coli: further evidence that factor H regulates the classical complement pathway

et al. 2011

View full text Add to dashboard Cite

Proteins of the complement system are known to interact with many charged substances. We recently characterized binding of C1q and factor H to immobilized and liposomal anionic phospholipids. Factor H inhibited C1q binding to anionic phospholipids, suggesting a role for factor H in regulating activation of the complement classical pathway by anionic phospholipids. To extend this finding, we examined interactions of C1q and factor H with lipid A, a well-characterized activator of the classical pathway. We report that C1q and factor H both bind to immobilized lipid A, lipid A liposomes and intact Escherichia coli TG1. Factor H competes with C1q for binding to these targets. Furthermore, increasing the factor H: C1q molar ratio in serum diminished C4b fixation, indicating that factor H diminishes classical pathway activation. The recombinant forms of the Cterminal, globular heads of C1q A, B and C chains bound to lipid A and E. coli in a manner qualitatively similar to native C1q, confirming that C1q interacts with these targets via its globular head region. These observations reinforce our proposal that factor H has an additional complement regulatory role of down-regulating classical pathway activation in response to certain targets. This is distinct from its role as an alternative pathway downregulator. We suggest that under physiological conditions, factor H may serve as a downregulator of bacterially-driven inflammatory responses, thereby finetuning and balancing the inflammatory response in infections with Gram-negative bacteria.

show abstract

Evasion of Immune Responses by Bacteria

Mills

Boyd

2010

Topley &Amp; Wilson's Microbiology and Microbial Infections

View full text Add to dashboard Cite

Mechanism of serum resistance among Brucella abortus isolates

Cited by 32 publications

References 21 publications

Deletion ofwboAEnhances Activation of the Lectin Pathway of Complement inBrucella abortusandBrucella melitensis

Deletion ofwboAEnhances Activation of the Lectin Pathway of Complement inBrucella abortusandBrucella melitensis

Interactions of complement proteins C1q and factor H with lipid A and Escherichia coli: further evidence that factor H regulates the classical complement pathway

Evasion of Immune Responses by Bacteria

Contact Info

Product

Resources

About