Role of OmpA1 and OmpA2 in Aggregatibacter actinomycetemcomitans and Aggregatibacter aphrophilus serum resistance

ABSTRACT Human diseases caused by species of Aeromonas have been classified into two major groups: septicemia and gastroenteritis. In this study, we reported the molecular and functional characterization of a new virulence factor, ToxR-regulated lipoprotein, or TagA, from a diarrheal isolate, SSU, of Aeromonas hydrophila. The tagA gene of A. hydrophila exhibited 60% identity with that of a recently identified stcE gene from Escherichia coli O157:H7, which encoded a protein (StcE) that provided serum resistance to the bacterium and prevented erythrocyte lysis by controlling classical pathway of complement activation by cleaving the complement C1-esterase inhibitor (C1-INH). We purified A. hydrophila TagA as a histidine-tagged fusion protein (rTagA) from E. coli DE3 strain using a T7 promoter-based pET30 expression vector and nickel affinity column chromatography. rTagA cleaved C1-INH in a time-dependent manner. The tagA isogenic mutant of A. hydrophila, unlike its corresponding wild-type (WT) or the complemented strain, was unable to cleave C1-INH, which is required to potentiate the C1-INH-mediated lysis of host and bacterial cells. We indeed demonstrated colocalization of C1-INH and TagA on the bacterial surface by confocal fluorescence microscopy, which ultimately resulted in increased serum resistance of the WT bacterium. Likewise, we delineated the role of TagA in contributing to the enhanced ability of C1-INH to inhibit the classical complement-mediated lysis of erythrocytes. Importantly, we provided evidence that the tagA mutant was significantly less virulent in a mouse model of infection (60%) than the WT bacterium at two 50% lethal doses, which resulted in 100% mortality within 48 h. Taken together, our data provided new information on the role of TagA as a virulence factor in bacterial pathogenesis. This is the first report of TagA characterization from any species of Aeromonas.

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Association between HACEK bacteraemia and endocarditis

Journal of Medical Microbiology ◽

10.1099/jmm.0.070060-0 ◽

2014 ◽

Vol 63 (6) ◽

pp. 892-895 ◽

Cited By ~ 18

Author(s):

Haur Sen Yew ◽

Stephen T. Chambers ◽

Sally A. Roberts ◽

David J. Holland ◽

Kylie A. Julian ◽

...

Keyword(s):

Positive Predictive Value ◽

Predictive Value ◽

Medical Records ◽

Aggregatibacter Actinomycetemcomitans ◽

Eikenella Corrodens ◽

Aggregatibacter Aphrophilus ◽

Haemophilus Parainfluenzae ◽

Duke Criteria

We retrospectively examined medical records of 87 patients with bacteraemia caused by members of the HACEK group (Haemophilus parainfluenzae, Aggregatibacter actinomycetemcomitans, Aggregatibacter aphrophilus, Aggregatibacter paraphrophilus, Cardiobacterium spp., Eikenella corrodens and Kingella spp.) to determine whether endocarditis was present, as defined by the Duke criteria. The overall positive predictive value (PPV) of HACEK bacteraemia for endocarditis was 60 %. The PPV varied with different HACEK species from 0 % (E. corrodens) to 100 % (A. actinomycetemcomitans).

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Genomic integration and expression of the Aggregatibacter actinomycetemcomitans catalase gene in Aggregatibacter aphrophilus

Archives of Oral Biology ◽

10.1016/j.archoralbio.2017.12.002 ◽

2018 ◽

Vol 86 ◽

pp. 116-122

Author(s):

Yuting Alice Yang ◽

Ya-An Cheng ◽

Casey Chen

Keyword(s):

Aggregatibacter Actinomycetemcomitans ◽

Genomic Integration ◽

Catalase Gene ◽

Aggregatibacter Aphrophilus

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Role of Virulence Factors in Resistance of Avian Pathogenic Escherichia coli to Serum and in Pathogenicity

Infection and Immunity ◽

10.1128/iai.71.1.536-540.2003 ◽

2003 ◽

Vol 71 (1) ◽

pp. 536-540 ◽

Cited By ~ 96

Author(s):

Melha Mellata ◽

Maryvonne Dho-Moulin ◽

Charles M. Dozois ◽

Roy Curtiss ◽

Peter K. Brown ◽

...

Keyword(s):

Escherichia Coli ◽

Virulence Factors ◽

Bacterial Resistance ◽

Serum Resistance ◽

Temperature Sensitive ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

K1 Capsule

ABSTRACT In chickens, colibacillosis is caused by avian pathogenic Escherichia coli (APEC) via respiratory tract infection. Many virulence factors, including type 1 (F1A) and P (F11) fimbriae, curli, aerobactin, K1 capsule, and temperature-sensitive hemagglutinin (Tsh) and plasmid DNA regions have been associated with APEC. A strong correlation between serum resistance and virulence has been demonstrated, but roles of virulence factors in serum resistance have not been well elucidated. By using mutants of APEC strains TK3, MT78, and χ7122, which belong to serogroups O1, O2, and O78, respectively, we investigated the role of virulence factors in resistance to serum and pathogenicity in chickens. Our results showed that serum resistance is one of the pathogenicity mechanisms of APEC strains. Virulence factors that increased bacterial resistance to serum and colonization of internal organs of infected chickens were O78 lipopolysaccharide of E. coli χ7122 and the K1 capsule of E. coli MT78. In contrast, curli, type 1, and P fimbriae did not appear to contribute to serum resistance. We also showed that the iss gene, which was previously demonstrated to increase resistance to serum in certain E. coli strains, is located on plasmid pAPEC-1 of E. coli χ7122 but does not play a major role in resistance to serum for strain χ7122.

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The OspE-Related Proteins Inhibit Complement Deposition and Enhance Serum Resistance ofBorrelia burgdorferi, the Lyme Disease Spirochete

Infection and Immunity ◽

10.1128/iai.01274-10 ◽

2011 ◽

Vol 79 (4) ◽

pp. 1451-1457 ◽

Cited By ~ 30

Author(s):

Melisha R. Kenedy ◽

Darrin R. Akins

Keyword(s):

Lyme Disease ◽

Mutant Strain ◽

Membrane Attack Complex ◽

Factor H ◽

Serum Resistance ◽

Complement Components ◽

Complement Inhibitors ◽

Related Proteins ◽

Complement Deposition

ABSTRACTBorrelia burgdorferi, the Lyme disease spirochete, binds the host complement inhibitors factor H (FH) and FH-like protein 1 (FHL-1). Binding of FH/FHL-1 by theB. burgdorferiproteins CspA and the OspE-related proteins is thought to enhance resistance to serum-mediated killing. While previous reports have shown that CspA confers serum resistance inB. burgdorferi, it is unclear whether the OspE-related proteins are relevant inB. burgdorferiserum resistance when OspE is expressed on the borrelial surface. To assess the role of the OspE-related proteins, we overexpressed them in a serum-sensitive CspA mutant strain. OspE overexpression enhanced serum resistance of the CspA-deficient organisms. Furthermore, FH was more efficiently bound to theB. burgdorferisurface when OspE was overexpressed. Deposition of complement components C3 and C5b-9 (the membrane attack complex), however, was reduced on the surface of the OspE-overexpressing strain compared to that on the CspA mutant strain. These data demonstrate that OspE proteins expressed on the surface ofB. burgdorferibind FH and protect the organism from complement deposition and subsequent serum-mediated destruction.

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