Characterisation and immune responses to meningococcal recombinant porin complexes incorporated into liposomes.

We have analysed the structure of meningococcal outer membrane complexes and found that the main complexes are formed by different combinations of PorA and/or PorB molecules, associated to other proteins such as RmpM. In view of the growing knowledge of the importance of conformational epitopes in the immune responses to many pathogens, our aim in this study was to analyse the interactions of PorA and PorB by reconstitution of both recombinant porins into liposomes and determine the relevance of these interactions for the immune response. Recombinant PorA and PorB incorporated into liposomes associate forming complexes that are homomeric when only one of the porins is present, but heteromeric when both neisserial porins are present, mimicking those found previously in native outer membrane vesicles (OMVs). Association of PorA and PorB to form heterocomplexes modifies the immunogenicity of at least PorB, allowing the production of antibodies that recognise conformational epitopes, and produces new epitopes that react with a 50 kDa outer membrane protein not yet identified.

Analysis of outer membrane porin complexes of Neisseria meningitidis in wild-type and specific knock-out mutant strains.

The structure of the porin complexes of Neisseria meningitidis was assessed in the vaccine strain H44/76 and its homologous mutants lacking the main porins (PorA and PorB) and other outer membrane (OM) components (RmpM and FetA). The analysis using 1-D blue native (BN) electrophoresis, 2-D BN/SDS-PAGE and 2-D diagonal electrophoresis, followed by LC/MS-MS (for 1-D gels) or MALDI-TOF (for 2-D gels) revealed at least six porin complexes in the wild-type strain with molecular masses (MW) ranging from 145 to 195 kDa and variable composition: The two higher MW complexes are formed by PorA, PorB and RmpM, the following three are formed by PorA and PorB, and the lower MW one is formed by only PorB. Complexes in the mutants lacking either PorA, PorB or RmpM, but not those in the mutant lacking FetA, were alterered respect to those in the wild-type strain. The most evident alteration was seen in the mutant lacking PorB, in which PorA formed only a high MW complex (approximately 800 kDa). Our results suggest that PorA and PorB could form a 'basic' template for the transportation systems in the OM of the meningococci. Other proteins (such as RmpM) could be transiently associated to the porin complexes, depending on the specific tranport needs at different stages of the meningococcal life cycle, resulting in a dynamic net of pores of variable composition.

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

The meningococcal NMB0035 locus encodes a 47 kDa outer-membrane protein that is highly conserved antigenically, and is able to induce antibodies during infection and bactericidal responses in vitro. This study analysed the surface exposure of this protein using specific antibodies in flow cytometry assays and determined its nucleotide sequence in 33 Neisseria strains. Genomic analyses revealed no significant differences in the nucleotide or amino acid sequences, but flow cytometry showed that surface accessibility was highly variable among the strains. These results suggest that masking by and/or association with lipo-oligosaccharides or other membrane molecules can be crucial for antigen accessibility, which must be thoroughly analysed in new vaccine candidates.

Bioinformatic analysis of outer membrane proteome of Neisseria meningitidis and Neisseria lactamica.

Two-dimensional electrophoresis (isoelectric focusing/SDS-PAGE) and Western-blotting techniques were used to analyze and compare common and/or specific outer-membrane proteins and antigens from Neisseria meningitidis and Neisseria lactamica. Bioinformatic image analyses of proteome and immunoproteome maps indicated the presence of numerous proteins and several antigens shared by N. meningitidis and N. lactamica, although the inter-strain variation in the maps was of similar magnitude to the inter-species variation, and digital comparison of the maps did not reveal proteins found to be identical by MALDI-TOF fingerprinting analysis. PorA and RmpM, two relevant outer-membrane antigens, manifested as various spots at several different positions. While some of these were common to all the strains analyzed, others were exclusive to N. meningitidis and their electrophoretic mobilities were different than expected. One such spot, with a molecular mass of 19 kDa, may be the C-terminal fragment of RmpM (RmpM-Cter). The results demonstrate that computer-driven analysis based exclusively on spot positions in the proteome or immunoproteome maps is not a reliable approach to predict the identity of proteins or antigens; rather, other identification techniques are necessary to obtain accurate comparisons.

Locus NMB0035 codes for a 47-kDa surface-accessible conserved antigen in Neisseria / El locus NMB0035 codifica un antígeno de superficie conservado de 47 kDa en Neisseria

A47 kDa neisserial outer-membrane antigenic protein (P47) was purified to homogeneity and used to prepare polyclonal anti-P47 antisera. Protein P47 was identified by MALDI-TOF fingerprinting analysis as the hypothetical lipoprotein NMB0035. Two-dimensional diagonal SDS-PAGE results suggested that, contrary to previous findings, P47 is not strongly associated with other proteins in membrane complexes. Western blotting with the polyclonal monospecific serum showed that linear P47 epitopes were expressed in similar amounts in the 27 Neisseria meningitidis strains tested and, to a lesser extent, in commensal Neisseria, particularly N. lactamica. However, dot-blotting assays with the same serum demonstrated binding variability between meningococcal strains, indicating differences in surface accessibility or steric hindrance by other surface structures. Specific anti-P47 antibodies were bactericidal against the homologous strain but had variable activity against heterologous strains, consistent with the results from dot-blotting experiments. An in-depth study of P47 is necessary to evaluate its potential as a candidate for new vaccine designs (AU)

El tratamiento con Triton X-114, seguido de la separación por SDS-PAGE permitió la purificación de una proteína antigénica de 47 kDa (P47) de la membrana externa de Neisseria de forma homogénea, lo que permitió la preparación de sueros policlonales anti-P47. La P47 se identificó como la lipoproteína (hipotética) NMB0035 mediante el análisis de la huella molecular realizado por MALDI-TOF. Los resultados obtenidos por SDS-PAGE diagonal bidimensional sugieren que, a diferencia de otros resultados previos, la P47 no parece estar fuertemente asociada a otras proteínas en complejos de membrana. Análisis de inmunoelectrotransferencia (Western blot) empleando el suero policlonal monoespecífico demostró que los epítopos lineales de la P47 se expresaron de forma similar en las 27 cepas de Neisseria meningitidis ensayadas y, aunque con menor intensidad, también lo hicieron en algunas Neisseria comensales, especialmente en N. lactamica. Sin embargo, resultados obtenidos por transferencia de mancha con el mismo suero demostraron que entre las cepas meningocócicas existe variabilidad en la capacidad de unión, lo que sugiere que o bien hay diferencias en la accesibilidad en superficie o bien una ocultación estérica producida por otras estructuras de superficie. Los anticuerpos específicos anti-P47 tenían efecto bactericida contra la cepa homóloga pero mostraron una actividad variable contra cepas heterólogas, lo cual concuerda con los resultados de la transferencia de mancha, y hace pensar que es necesario estudiar esta proteína más profundamente para evaluar su potencial como candidata para nuevos diseños de vacunas (AU)

Cross-linking analysis of antigenic outer membrane protein complexes of Neisseria meningitidis.

Polysaccharide-based approaches have not enabled the development of effective vaccines against meningococci of serogroup B, and the most promising current research is focused on the use of outer membrane vesicles. Due to the toxicity of the outer membrane oligosaccharides, new vaccines based on purified proteins are being sought, but despite the application of advanced techniques, they remain elusive, perhaps due to the fact that standard techniques for analysis of antigens overlook conformational epitopes located in membrane complexes. Membrane complex antigens have been analyzed in Neisseria gonorrhoeae, and a study published on Neisseria meningitidis has reported the in vitro formation of 800-kD complexes by deposition of a purified protein (MSP63) onto synthetic lipid layers; however, no studies to date have attempted to identify membrane complexes present in vivo in N. meningitidis. In the present study, cross-linking with formaldehyde was used to identify outer membrane protein associations in various N. meningitidis and Neisseria lactamica strains. In N. meningitides, complexes of about 450 kD (also present in N. lactamica), 165 and 95 kD were detected and shown to be made up of the proteins MSP63, PorA/PorB/RmpM/FetA, and PorA/PorB/RmpM, respectively. In western blots, the 450-kD complex was identified by mouse antibodies raised against outer membrane vesicles, but not by antibodies raised against the purified complex, demonstrating the importance of conformational epitopes, and thus suggesting that the analysis of antigens in their native conformation may be useful or even essential for the design of effective vaccines against meningococci.

Locus NMB0035 codes for a 47-kDa surface-accessible conserved antigen in Neisseria.

A47 kDa neisserial outer-membrane antigenic protein (P47) was purified to homogeneity and used to prepare polyclonal anti-P47 antisera. Protein P47 was identified by MALDI-TOF fingerprinting analysis as the hypothetical lipoprotein NMB0035. Two-dimensional diagonal SDS-PAGE results suggested that, contrary to previous findings, P47 is not strongly associated with other proteins in membrane complexes. Western blotting with the polyclonal monospecific serum showed that linear P47 epitopes were expressed in similar amounts in the 27 Neisseria meningitidis strains tested and, to a lesser extent, in commensal Neisseria, particularly N. lactamica. However, dot-blotting assays with the same serum demonstrated binding variability between meningococcal strains, indicating differences in surface accessibility or steric hindrance by other surface structures. Specific anti-P47 antibodies were bactericidal against the homologous strain but had variable activity against heterologous strains, consistent with the results from dot-blotting experiments. An in-depth study of P47 is necessary to evaluate its potential as a candidate for new vaccine designs.

Analysis of outer membrane protein complexes and heat-modifiable proteins in Neisseria strains using two-dimensional diagonal electrophoresis.

Two-dimensional diagonal SDS-PAGE was used to resolve membrane complexes and identify proteins with temperature-dependent mobility in Neisseria meningitidis and N. lactamica. The main membrane complexes were composed of porins and were formed by heteromers of PorA, PorB and RmpM in N. meningitidis, and by PorB and RmpM in N. lactamica. Also, other proteins, including Opa, with temperature-dependent mobility were clearly demonstrated. The method allows improved detection of the components of membrane complexes and proteins with temperature-dependent mobility which is difficult to resolve with other analytical approaches.

Olanzapine for the treatment of chronic refractory schizophrenia: a 12-month follow-up naturalistic study.

OBJECTIVE: The aim of this study is to provide long-term data on the effectiveness and safety of olanzapine in a group of patients with severe refractory schizophrenia. GENERAL METHODS: Twenty patients who had previously received treatment with typical antipsychotic agents and who met the DSM-IV criteria of schizophrenia and refractoriness to treatment were evaluated in a 1-year prospective study after switching to olanzapine. The Positive and Negative Symptoms Scale (PANSS) and the Brief Psychiatric Rating Scale (BPRS) were used to measure effectiveness. The extrapyramidal symptoms were also recorded. Serial laboratory tests, electrocardiograms and body weight measurements were also performed. Longitudinal statistical analyses were performed on the global changes in the scores of the scales by means of a repeated measures analysis of variance. RESULTS: Significant reductions in the global scores from baseline in the PANSS, as well as in the BPRS, were observed. Furthermore, these reductions were also significant when considered only from Week 12. Olanzapine was, in general, well tolerated; a weight gain was observed between baseline and Month 4.5, but, interestingly, it decreased again from this time point to Month 12. CONCLUSION: Olanzapine was shown to be a suitable treatment for refractory schizophrenia in this series of seriously ill patients. Although most of the effects were observed before Week 12, improvement persisted after 1 year. Weight gain stopped or even regressed when the treatment was prolonged. Large controlled clinical trials to define the role of atypical antipsychotics for the management of treatment-refractory schizophrenia are necessary.