Bactericidal effect of pooled human serum on Bacteroides melaninogenicus, Bacteroides asaccharolyticus and Actinobacillus actinomycetemcomitans

Sundqvist, Göran; Johansson, E.

doi:10.1111/j.1600-0722.1982.tb01521.x

Cited by 45 publications

(56 citation statements)

References 37 publications

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“…P. gingivalis is resistant to killing by host complement, and it is believed that capsule plays a central role in the resistance (57,63). Since ⌬PG352 has a defective capsule, we hypothesize that the mutant might become sensitive to the complement killing.…”

Section: Resultsmentioning

confidence: 95%

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Abrogation of Neuraminidase Reduces Biofilm Formation, Capsule Biosynthesis, and Virulence of Porphyromonas gingivalis

Kurniyati

Hu³

et al. 2012

Infect Immun

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The oral bacterium Porphyromonas gingivalis is a key etiological agent of human periodontitis, a prevalent chronic disease that affects up to 80% of the adult population worldwide. P. gingivalis exhibits neuraminidase activity. However, the enzyme responsible for this activity, its biochemical features, and its role in the physiology and virulence of P. gingivalis remain elusive. In this report, we found that P. gingivalis encodes a neuraminidase, PG0352 (Sia Pg ). Transcriptional analysis showed that PG0352 is monocistronic and is regulated by a sigma 70 -like promoter. Biochemical analyses demonstrated that Sia Pg is an exo-␣-neuraminidase that cleaves glycosidic-linked sialic acids. Cryoelectron microscopy and tomography analyses revealed that the PG0352 deletion mutant (⌬PG352) failed to produce an intact capsule layer. Compared to the wild type, in vitro studies showed that ⌬PG352 formed less biofilm and was less resistant to killing by the host complement. In vivo studies showed that while the wild type caused a spreading type of infection that affected multiple organs and all infected mice were killed, ⌬PG352 only caused localized infection and all animals survived. Taken together, these results demonstrate that Sia Pg is an important virulence factor that contributes to the biofilm formation, capsule biosynthesis, and pathogenicity of P. gingivalis, and it can potentially serve as a new target for developing therapeutic agents against P. gingivalis infection.

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Section: Resultsmentioning

confidence: 95%

“…P. gingivalis is resistant to complement killing (63). Compared to the wild type, the ⌬PG352 mutant became more vulnerable to serum killing (Fig.…”

Section: Discussionmentioning

confidence: 99%

Abrogation of Neuraminidase Reduces Biofilm Formation, Capsule Biosynthesis, and Virulence of Porphyromonas gingivalis

Kurniyati

Hu³

et al. 2012

Infect Immun

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“…Since the work of Sundqvist and Johansson (37) showed that Bacteroides asaccharolyticus, later reclassified as P. gingivalis, is resistant to killing by complement in serum, several groups have investigated the cause of this resistance. Sundqvist et al (38) showed that complement components are susceptible to degradation by protease(s) produced by P. gingivalis.…”

Section: Discussionmentioning

confidence: 99%

“…Cells were harvested, washed once in complement fixation diluent (CFD) (tablet form; Oxoid), and adjusted to an optical density at 595 nm (OD 595 ) of 0.5 (approximately 10 7 CFU ml Ϫ1 ). Conditions for measurement of bacterial killing were established with P. melaninogenica, ATCC 25845, which has been shown to be sensitive to complement (37). Aliquots of 0.8 ml bacteria in triplicate were incubated anaerobically with 0.2 ml serum for 0 and 60 min and with heatinactivated serum for 60 min.…”

Section: Methodsmentioning

confidence: 99%

Mechanisms of Resistance ofPorphyromonas gingivalisto Killing by Serum Complement

Slaney¹,

Gallagher²,

Aduse‐Opoku³

et al. 2006

Infect Immun

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The complement system plays an important role in the host defense against infection, and the formation of the terminal complement complex on the bacterial surface has been shown to be particularly important in killing of gram-negative bacteria. The gram-negative periodontal pathogen Porphyromonas gingivalis is resistant to complement killing, and possible mechanisms suggested for this resistance include protease production and capsule formation. In this study, P. gingivalis Arg-and Lys-gingipain deletion mutants and polysaccharide synthesis deletion mutants have been used to investigate these hypotheses. When Arg-and Lys-gingipain protease mutants were incubated in 20% normal human serum, deposition of complement components on the cell surface was significantly increased compared to that for the wild-type organism. However, despite the increased deposition, the protease mutants maintained resistance to killing and their viability was equal to that seen with heat-inactivated serum. Similar data were obtained when the wild-type organism was treated with gingipain protease inhibitors. K-antigen expression mutants were also resistant to killing. However, mutants which no longer synthesized a surface anionic polysaccharide (APS) (a phosphorylated branched mannan) were extremely sensitive to serum killing. These mutants lack the organized dense glycan surface layer present on the parent strain on the basis of electron microscopy. We conclude that the production of APS at the surface of P. gingivalis rather than Arg-and Lys-gingipain synthesis is the principal mechanism of serum resistance in P. gingivalis.

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“…It has been shown that most strains of P. gingivalis are resistant to the bactericidal lytic activity of human serum (14,15), and gingipains are implicated as the major factor exerting protection against complement. HRgpA cleaves purified C3 and C5, leading first to the release of active fragments such as C5a and C3b followed by degradation and loss of function by these complement factors (16).…”

mentioning

confidence: 99%

Biphasic Effect of Gingipains from Porphyromonas gingivalis on the Human Complement System

Popadiak

Potempa

Riesbeck

et al. 2007

The Journal of Immunology

158

214

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Periodontitis is an inflammatory disease of the supporting structures of the teeth and is caused by, among other agents, Porphyromonas gingivalis. P. gingivalis is very resistant to killing by human complement, which is present in a gingival fluid at 70% of the serum concentration. We found that the incubation of human serum with purified cysteine proteases of P. gingivalis (gingipains) or P. gingivalis wild-type strains W83 and W50 resulted in a drastic decrease of the bactericidal activity of the serum. In contrast, serum treated with P. gingivalis mutants lacking gingipains (particularly strains without HRgpA) maintained significant bactericidal activity. To understand in detail the mechanism by which gingipains destroy the serum bactericidal activity, we investigated the effects of gingipains on the human complement system. We found that all three proteases degraded multiple complement components, with arginine-specific gingipains (HRgpA and RgpB) being more efficient than lysine-specific gingipain (Kgp). Interestingly, all three proteases at certain concentrations were able to activate the C1 complex in serum, which resulted in the deposition of C1q on inert surfaces and on bacteria themselves. It is therefore plausible that P. gingivalis activates complement when present at low numbers, resulting in a local inflammatory reaction and providing the bacteria with a colonization opportunity and nutrients. At later stages of infection the concentration of proteases is high enough to destroy complement factors and thus render the bacteria resistant to the bactericidal activity of complement.

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Bactericidal effect of pooled human serum on Bacteroides melaninogenicus, Bacteroides asaccharolyticus and Actinobacillus actinomycetemcomitans

Cited by 45 publications

References 37 publications

Abrogation of Neuraminidase Reduces Biofilm Formation, Capsule Biosynthesis, and Virulence of Porphyromonas gingivalis

Abrogation of Neuraminidase Reduces Biofilm Formation, Capsule Biosynthesis, and Virulence of Porphyromonas gingivalis

Mechanisms of Resistance ofPorphyromonas gingivalisto Killing by Serum Complement

Biphasic Effect of Gingipains from Porphyromonas gingivalis on the Human Complement System

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