A cross-reactive neisserial antigen encoded by the NMB0035 locus shows high sequence conservation but variable surface accessibility

Arenas, Jesús; Abel, Ana; Sánchez, Sandra; Marzoa, Juan; Berrón, S.; Ley, Peter van der; Criado, M.T.; Ferreirós, C.M.

doi:10.1099/jmm.0.47172-0

Cited by 12 publications

(6 citation statements)

References 34 publications

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“…Bacterial cells were fixed with 1% (v/v) formaldehyde as previously described (Arenas et al, 2008). Fixed bacteria were washed and incubated at a concentration of 10 7 cells ml −1 in PBS-T containing 1% (w/v) BSA (PBS-T-BSA) at room temperature.…”

Section: Immunofluorescence Microscopymentioning

confidence: 99%

“…Vaccines based on capsular polysaccharides are effective in conferring immunity but not against strains of serogroup B because of low immunogenicity of the corresponding polysaccharide. Vaccines based on non-capsular antigens were developed, but a definite formulation is still not available mainly because of diverse immune-evasion strategies of the bacterium, including phase variation, which is a reversible turning on and off of protein expression Tauseef et al, 2013), antigenic variation (Virji, 2009) and/or variable accessibility of noncapsular surface structures (Arenas et al, 2008). Thus, meningococcal infection remains a worldwide problem and requires better understanding of the role of surfaceexposed structures.…”

Section: Introductionmentioning

confidence: 99%

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The meningococcal autotransporter AutA is implicated in autoaggregation and biofilm formation

Arenas

Cano-Crespo

Nijland

et al. 2014

Environmental Microbiology

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Autotransporters (ATs) are proteins secreted by Gram-negative bacteria that often play a role in virulence. Eight different ATs have been identified in Neisseria meningitidis, but only six of them have been characterized. AutA is one of the remaining ATs. Its expression remains controversial. Here, we show that the autA gene is present in many neisserial species, but its expression is often disrupted by various genetic features; however, it is expressed in certain strains of N. meningitidis. By sequencing the autA gene in large panels of disease isolates and Western blot analysis, we demonstrated that AutA expression is prone to phase variation at AAGC nucleotide repeats located within the DNA encoding the signal sequence. AutA is not secreted into the extracellular medium, but remains associated with the bacterial cell surface. We further demonstrate that AutA expression induces autoaggregation in a process that, dependent on the particular strain, may require extracellular DNA (eDNA). This property influences the organization of bacterial communities like lattices and biofilms. In vitro assays evidenced that AutA is a self-associating AT that binds DNA. We suggest that AutA-mediated autoaggregation might be particularly important for colonization and persistence of the pathogen in the nasopharynx of the host.

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Section: Immunofluorescence Microscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The meningococcal autotransporter AutA is implicated in autoaggregation and biofilm formation

Arenas

Cano-Crespo

Nijland

et al. 2014

Environmental Microbiology

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“…To determine the level of expression of fluorescent proteins expressed by each pIN variant, cell were fixed by adding formaldehyde (1% v/v) to an exponentially growing culture as described (Arenas et al, 2008) and formalin-fixed cells were visualized by fluorescence microscopy. An outline was drawn around 20 formalin-fixed cells, and the mean fluorescence was measured, along with several adjacent background readings.…”

Section: Methodsmentioning

confidence: 99%

Interstrain Cooperation in Meningococcal Biofilms: Role of Autotransporters NalP and AutA

et al. 2017

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Neisseria meningitidis (Nm) and Neisseria lactamica (Nl) are commensal bacteria that live in the human nasopharynx, where they form microcolonies. In contrast to Nl, Nm occasionally causes blood and/or meningitis infection with often fatal consequences. Here, we studied interactions between neisserial strains during biofilm formation. Fluorescent strains were engineered and analyzed for growth in single- and dual-strain biofilms with confocal laser-scanning microscopy. Different strains of diverse Neisseria species formed microcolonies of different sizes and morphologies. Pair-wise combinations of two invasive Nm strains and one Nm carrier isolate showed that these strains can coexist in spite of the fact that they produce toxins to combat congeners. This lack of competition was even observed when the biofilms were formed under nutrient limitation and can be explained by the observation that the separate microcolonies within mixed biofilms are mostly lineage specific. However, these microcolonies showed different levels of interaction. The coexistence of two strains was also observed in mixed biofilms of Nm and Nl strains. Inactivation of the autotransporter NalP, which prevents the release of the heparin-binding antigen NHBA and the α-peptide of IgA protease from the cell surface, and/or the production of autotransporter AutA increased interactions between microcolonies, as evidenced by close contacts between microcolonies on the substratum. Qualitative and quantitative analysis revealed an altered spatial distribution of each strain in mixed biofilms with consequences for the biomass, biofilm architecture and bacterial viability depending on the synthesis of NalP and AutA, the expression of which is prone to phase variation. Being in a consortium resulted in some cases in commensalism and cooperative behavior, which promoted attachment to the substratum or increased survival, possibly as result of the shared use of the biofilm matrix. We hypothesize that Nm strains can cooperate during host colonization, but, possibly, the different capacities of the microcolonies of each strain to resist the host's defenses limits the long-term coexistence of strains in the host.

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“…17,2010 ADJUVANT EFFECT OF LpxL1 AND PagL LPS IN Opa-LIPOSOMES 493 accessibility of MAbs to certain OMPs when different types of LPS were expressed (1,5). This association is probably maintained by hydrophobic and charge interactions between LPS and specific protein domains (7).…”

Section: Discussionmentioning

confidence: 99%

“…Vaccines based on capsular polysaccharides confer protection against bacteria of the same serogroup, but, unfortunately, the serogroup B capsular polysaccharide cannot be used due to its poor immunogenicity in humans and the potential risk of autoimmunity (17). Subcapsular antigens, mainly outer membrane proteins (OMPs) (1,11,48), have been extensively examined as alternative candidates for the development of a vaccine against this serogroup.…”

Section: Meningococcal Disease Is a Systemic Infection Caused Bymentioning

confidence: 99%

Coincorporation of LpxL1 and PagL Mutant Lipopolysaccharides into Liposomes withNeisseria meningitidis Opacity Protein: Influence on Endotoxic and Adjuvant Activity

Arenas

Dijken²,

Kuipers³

et al. 2010

Clin Vaccine Immunol

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Wild-type lipopolysaccharide (LPS) of Neisseria meningitidis normally contains six acyl chains. Pentaacylated LPS forms were generated through inactivation of the lpxL1 gene or through the expression of the Bordetella bronchiseptica pagL gene in N. meningitidis. The resulting LPS species, designated LpxL1 LPS and PagL LPS, respectively, display reduced endotoxic activity compared to wild-type LPS. Here, we determined the adjuvant potential of PagL LPS by comparison with the broadly used LpxL1 LPS. We also investigated the potential benefit for adjuvanticity of coincorporating these LPS species, together with the meningococcal opacity-associated protein OpaJ as a model antigen, in a liposomal delivery system. PagL LPS showed a higher endotoxic activity than LpxL1 LPS, and their incorporation into liposomes significantly reduced their endotoxic activity as determined by measuring the induction of interleukin-6 (IL-6) production in a murine macrophage cell line. To determine the adjuvant effect, BALB/c mice were immunized with OpaJ-containing liposomes and either free LPS or LPS coincorporated into the proteoliposomes. OpaJ-containing liposomes adjuvanted with AlPO 4 or not adjuvanted at all were included as control groups. In the appropriate dose, PagL LPS showed a superior adjuvant effect compared with LpxL1 LPS, and for both LPS types, free LPS showed a higher adjuvant effect than when coincorporated into the liposomes, as evidenced by higher titers of IgG2a and IgG2b antibodies against OpaJ ؉ meningococci and higher bactericidal titers. In conclusion, PagL LPS is a better adjuvant than LpxL1 LPS, but coincorporation of either LPS into proteoliposomes did not improve their adjuvant activity.

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A cross-reactive neisserial antigen encoded by the NMB0035 locus shows high sequence conservation but variable surface accessibility

Cited by 12 publications

References 34 publications

The meningococcal autotransporter AutA is implicated in autoaggregation and biofilm formation

The meningococcal autotransporter AutA is implicated in autoaggregation and biofilm formation

Interstrain Cooperation in Meningococcal Biofilms: Role of Autotransporters NalP and AutA

Coincorporation of LpxL1 and PagL Mutant Lipopolysaccharides into Liposomes withNeisseria meningitidis Opacity Protein: Influence on Endotoxic and Adjuvant Activity

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