Dataset Information

Correlation between serological and sequencing analyses of the PorB outer membrane protein in the Neisseria meningitidis serotyping system.

ABSTRACT: The current serological typing scheme for Neisseria meningitidis is not comprehensive; a proportion of isolates are not serotypeable. DNA sequence analysis and predicted amino acid sequences were used to characterize the structures of variable-region (VR) epitopes on N. meningitidis PorB proteins (PorB VR typing). Twenty-six porB gene sequences were obtained from GenBank and aligned with 41 new sequences. Primary amino acid structures predicted from those genes were grouped into 30 VR families of related variants that displayed at least 60% similarity. We correlated VR families with monoclonal antibody (MAb) reactivities, establishing a relationship between VR families and epitope locations for 15 serotype-defining MAbs. The current panel of serotype-defining MAbs underestimates by at least 50% the PorB VR variability because reagents for several major VR families are lacking or because a number of VR variants within some families are not recognized by serotype-defining MAbs. These difficulties, also reported for serosubtyping based on the PorA protein, are shown as inconsistent results between serological and sequence analyses, leading to inaccurate strain identification and incomplete epidemiological data. The information from this study enabled the expansion of the panel of MAbs currently available for serotyping, by including MAbs of previously undetermined specificities. Use of the expanded serotype panel enabled us to improve the sensitivity of serotyping by resolving a number of formerly nonserotypeable strains. In most cases, this information can be used to predict the VR family placement of unknown PorB proteins without sequencing the entire porB gene. PorB VR typing complements serotyping, and a combination of both techniques may be used for full characterization of meningococcal strains. The present work represents the most complete and integrated data set of PorB VR sequences and MAb reactivities of serogroup B and C meningococci produced to date.

SUBMITTER: Sacchi CT

PROVIDER: S-EPMC104523 | biostudies-literature | 1998 May

REPOSITORIES: biostudies-literature

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Correlation between serological and sequencing analyses of the PorB outer membrane protein in the Neisseria meningitidis serotyping system.

Sacchi C T CT Lemos A P AP Whitney A M AM Solari C A CA Brandt M E ME Melles C E CE Frasch C E CE Mayer L W LW

Clinical and diagnostic laboratory immunology 19980501 3

The current serological typing scheme for Neisseria meningitidis is not comprehensive; a proportion of isolates are not serotypeable. DNA sequence analysis and predicted amino acid sequences were used to characterize the structures of variable-region (VR) epitopes on N. meningitidis PorB proteins (PorB VR typing). Twenty-six porB gene sequences were obtained from GenBank and aligned with 41 new sequences. Primary amino acid structures predicted from those genes were grouped into 30 VR families o ...[more]

PMID: 9605990

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Project description:BackgroundOuter membrane vesicles (OMVs) are nanoparticles released by Gram-negative bacteria and can be used as vaccines. Often, detergents are used to promote release of OMVs and to remove the toxic lipopolysaccharides. Lipopolysaccharides can be detoxified by genetic modification such that vesicles spontaneously produced by bacteria can be directly used as vaccines. The use of spontaneous OMVs has the advantage that no separate extraction step is required in the purification process. However, the productivity of spontaneous OMVs by bacteria at optimal growth conditions is low. One of many methods for increasing OMV formation is to reduce the linkage of the outer membrane to the peptidoglycan layer by knocking out the rmpM gene. A previous study showed that for Neisseria meningitidis this resulted in release of more OMVs. Furthermore, cysteine depletion was found to trigger OMV release and at the same time cause reduced growth and oxidative stress responses. Here we study the effect of growth rate and oxidative stress on OMV release.ResultsFirst, we identified using chemostat and accelerostat cultures of N. meningitidis that increasing the growth rate from 0.03 to 0.18 h-1 has a limited effect on OMV productivity. Thus, we hypothesized that oxidative stress is the trigger for OMV release and that oxidative stress can be introduced directly by increasing the dissolved oxygen tension of bacterial cultures. Slowly increasing oxygen concentrations in a N. meningitidis changestat showed that an increase from 30 to 150% air saturation improved OMV productivity four-fold. Batch cultures controlled at 100% air saturation increased OMV productivity three-fold over batch cultures controlled at 30% air saturation.ConclusionIncreased dissolved oxygen tension induces the release of outer membrane vesicles in N. meningitidis cultures. Since oxygen concentration is a well-controlled process parameter of bacterial cultures, this trigger can be applied as a convenient process parameter to induce OMV release in bacterial cultures. Improved productivity of OMVs not only improves the production costs of OMVs as vaccines, it also facilitates the use of OMVs as adjuvants, enzyme carriers, or cell-specific drug delivery vehicles.

Dataset Information

Correlation between serological and sequencing analyses of the PorB outer membrane protein in the Neisseria meningitidis serotyping system.

Publications

Correlation between serological and sequencing analyses of the PorB outer membrane protein in the Neisseria meningitidis serotyping system.

Similar Datasets

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