Jun X. Wheeler

Quantitation of haemagglutinin in H5N1 influenza viruses reveals low haemagglutinin content of vaccine virus NIBRG-14 (H5N1)

The assessment of potential candidate influenza vaccine viruses includes a number of factors. Growth properties of the virus and yield of antigen, specifically the haemagglutinin (HA), are of key importance. The recently developed H5N1 candidate vaccine virus NIBRG-14 (with HA and NA genes derived from the clade 1 virus A/Viet Nam/1194/2004 in an A/Puerto Rico/8/34 background) has been suggested to yield low amounts of antigen. While investigating the antigen yield of H5N1 vaccine viruses, we found that accurate quantitation of the HA content of some H5N1 viruses was difficult due to the migration characteristics of the proteins on SDS-PAGE gels. The HA1 and HA2 bands co-migrated with nucleoprotein (NP) and matrix protein (M1) respectively, preventing accurate analysis. We have developed an accurate way of quantitating HA from these H5N1 viruses by introducing a deglycosylation step to the standard protocol. Using this method, we showed reproducibly that the low yield of NIBRG-14 is, at least in part, due to a lower than usual content of HA in virus preparations. This was also found to be the case for the parent wild type A/Viet Nam/1194/2004 virus.

Characterisation of the Protein Content of a Meningococcal Outer Membrane Vesicle Vaccine by Polyacrylamide Gel Electrophoresis and Mass Spectrometry

The development and evaluation of outer membrane vesicles as vaccines against meningococcal disease has been carried out for more than two decades. Although such vaccines have limitations and are not widely licensed, they continue to be used to disrupt clonal outbreaks caused by group B meningococci and a wealth of information is now available from large-scale clinical studies. One dimensional polyacrylamide gel electrophoresis and semi-quantitative measurement of the major proteins is one method used to evaluate and control these products. However, it is often difficult to determine exactly which bands on a one dimensional gel correspond to the key antigens whose presence must be demonstrated for control and lot release. We have therefore carried out mass spectrometric analyses of outer membrane vesicle vaccine samples to definitively identify the bands containing seven key antigens: Omp85, FetA, PorA, PorB, RmpM, OpcA and NspA. An additional 33 proteins present in the vaccine were also identified and this information will be useful both for future quality control and for the interpretation of data from vaccine trials.

Characterization of the key antigenic components and pre-clinical immune responses to a meningococcal disease vaccine based on Neisseria lactamica outer membrane vesicles

Serogroup B strains are now responsible for over 80% of meningococcal disease in the UK and no suitable vaccine is available that confers universal protection against all serogroup B strains. Neisseria lactamica shares many antigens with the meningococcus, except capsule and the surface protein PorA. Many of these antigens are thought to be responsible for providing cross-protective immunity to meningococcal disease. We have developed an N. lactamica vaccine using methods developed for meningococcal outer membrane vesicle (OMV) vaccines. The major antigenic components were identified by excision of 11 major protein bands from an SDS-PAGE gel, followed by mass spectrometric identification. These bands contained at least 22 proteins identified from an unassembled N. lactamica genome, 15 of which having orthologues in published pathogenic Neisseria genomes. Western blotting revealed that most of these bands were immunogenic, and antibodies to these proteins generally cross-reacted with N. meningitidis proteins. Sera from mice and rabbits immunised with either N. lactamica or N. meningitidis OMVs produced comparable cross-reactive ELISA titres against OMVs prepared from a panel of diverse meningococcal strains. Mice immunised with either N. meningitidis or N. lactamica OMVs showed no detectable serum bactericidal activity against the panel of target strains except N. meningitidis OMV sera against the homologous strain. Similarly, rabbit antisera to N. lactamica OMVs elicited little or no bactericidal antibodies against the panel of serogroup B meningococcal strains. However, such antisera did mediate opsonophagocytosis, suggesting that this may be a mechanism by which this vaccine protects in a mouse model of meningococcal bacteraemia.

Physicochemical and biological assays for quality control of biopharmaceuticals: Interferon alfa-2 case study

A selection of physicochemical and biological assays were investigated for their utility in detecting changes in preparations of Interferon alpha-2a and Interferon alpha-2b (IFN-alpha 2a, IFN-alpha 2b), which had been subjected to stressed conditions, in order to create models of biopharmaceutical products containing product-related impurities. The stress treatments, which included oxidation of methionine residues and storage at elevated temperatures for different periods of time, were designed to induce various degrees of degradation, aggregation or oxidation of the interferon. Biological activity of the stressed preparations was assessed in three different in vitro cell-based bioassay systems: a late-stage anti-proliferative assay and early-stage assays measuring reporter gene activation or endogenous gene expression by quantitative real time Reverse Transcription-Polymerase Chain Reaction (qRT-PCR). Relevant physicochemical methods such as SDS-PAGE, reverse phase (RP) chromatography, size-exclusion chromatography (SEC) and dynamic light scattering (DLS), proved their complementarity in detecting structural changes in the stressed preparations which were reflected by reductions in biological activity.

Identification of vaccine antigens using integrated proteomic analyses of surface immunogens from serogroup B Neisseria meningitidis

UNLABELLED Meningococcal surface proteins capable of evoking a protective immune response are candidates for inclusion in protein-based vaccines against serogroup B Neisseria meningitidis (NmB). In this study, a 2-dimensional (2-D) gel-based platform integrating surface and immune-proteomics was developed to characterize NmB surface protein antigens. The surface proteome was analyzed by differential 2-D gel electrophoresis following treatment of live bacteria with proteinase K. Alongside, proteins recognized by immune sera from mice challenged with live meningococci were detected using 2-D immunoblots. In combination, seventeen proteins were identified including the well documented antigens PorA, OpcA and factor H-binding protein, previously reported potential antigens and novel potential immunogens. Results were validated for the macrophage infectivity potentiator (MIP), a recently proposed NmB vaccine candidate. MIP-specific antisera bound to meningococci in whole-cell ELISA and facilitated opsonophagocytosis and deposition of complement factors on the surface of meningococcal isolates of different serosubtypes. Cleavage by proteinase K was confirmed in western blots and shown to occur in a fraction of the MIP expressed by meningococci suggesting transient or limited surface exposure. These observations add knowledge for the development of a protein NmB vaccine. The proteomic workflow presented here may be used for the discovery of vaccine candidates against other pathogens. BIOLOGICAL SIGNIFICANCE This study presents an integrated proteomic strategy to identify proteins from N. meningitidis with desirable properties (i.e. surface exposure and immunogenicity) for inclusion in subunit vaccines against bacterial meningitis. The effectiveness of the method was demonstrated by the identification of some of the major meningococcal vaccine antigens. Information was also obtained about novel potential immunogens as well as the recently described potential antigen macrophage infectivity potentiator which can be useful for its consideration as a vaccine candidate. Additionally, the proteomic strategy presented in this study provides a generic 2-D gel-based platform for the discovery of vaccine candidates against other bacterial infections.

Exploring the proteome of meningococcal outer membrane vesicle vaccines

Neisseria meningitidis, one of the principal causes of bacterial meningitis and septicemia, continues to present a challenge for vaccine developers. While significant progress has been made in the development and implementation of conjugate vaccines, which are based on the capsular polysaccharide of the organism, this approach has failed to produce a vaccine against organisms expressing a serogroup B capsule. The completion of the first meningococcal genome sequences in 2000 provided new ways of meeting this challenge. One approach has been to learn more about meningococcal biology and pathogenesis through exploring its proteome. This article reviews the results of ten recent studies of the meningococcal proteome and compares the different methodologies employed. Not surprisingly, given the renewed impetus to develop a comprehensive vaccine and the continuing clinical development of outer membrane vesicle vaccines, many of these studies focus on the proteome of the outer membrane fraction. As in other areas of proteome research, the direct comparison of data from different studies is hampered by the lack of standardization of separation technologies and data formats. Nevertheless, proteomic analysis, especially when combined with detailed knowledge of meningococcal population structures, represents a powerful tool in the development of vaccines against this important pathogen.

Proteomic analysis of rat plasma following transient focal cerebral ischemia

AIM This study aimed to identify plasma protein changes in a rat model of ischemic stroke using a proteomic approach. MATERIALS & METHODS Four male Sprague-Dawley rats (3-6 months old) were subjected to 90 min of left middle cerebral artery occlusion under anesthesia with 1.5% isoflurane in O(2)/air followed by 24-h reperfusion. Blood samples (~100 µl) were collected at baseline, at the end of 90-min middle cerebral artery occlusion and at 24-h postreperfusion. Brain injuries were assessed by MRI at 24-h postreperfusion. Quantitative comparison of global plasma protein expression was performed using 2D differential in-gel electrophoresis. Differentially expressed protein spots were identified using peptide sequencing tandem mass spectrometry. RESULTS These rats had clear brain infarction in the left hemisphere detected by MRI. Thirty-three protein spots of plasma samples were differentially expressed following focal cerebral ischemia/reperfusion. These protein spots belonged to eight proteins. Six of them (α2-macroglobulin, complement C3, inter-α- trypsin inhibitor heavy chain H3, serum albumin, haptoglobin and transthyretin), which are a class of acute-phase proteins, changed significantly. CONCLUSION This study describes the responses of young rats to focal cerebral ischemia and suggests that future studies should use aged animals to better mimic the clinical ischemic stroke setting.

Comparison of two combinations of cyanine dyes for prelabelling and gel electrophoresis.

We report the use of IC‐OSu ethyl‐Cy3 and ethyl‐Cy5 N‐hydroxysuccinimide ester (NHS) cyanine dyes, which have similar chemical properties as the CyDye™ DIGE fluor minimal dyes for pre‐electrophoresis labelling. Multiple sample analyses in different laboratories indicate that the use of IC‐OSu ethyl‐Cy3 and ethyl‐Cy5 NHS ester cyanine dyes produces equivalent results to those obtained with DIGE CyDyes, and allows sample multiplexing and accurate quantitation for differential proteome analysis.Schizophrenia is a debilitating condition associated with high morbidity and mortality. While currently available atypical antipsychotic agents have significantly advanced the treatment of schizophrenia, there is still a great unmet need for new, effective and better-tolerated therapies. Iloperidone, a D(2)/5-HT(2) receptor antagonist, has been recently approved by the US FDA for the acute treatment of schizophrenia in adults. Iloperidone has been shown to be effective in the treatment of schizophrenia in four short-term (4-6 weeks) and three long-term (52 weeks) studies with over 3000 patients exposed to treatment. Results also indicated a reassuring safety profile, particularly regarding extrapyramidal symptoms, akathisia and prolactin elevation, with a modest effect on weight gain and no medically important changes in cholesterol, triglycerides and glucose. As other antipsychotics, iloperidone has been shown to prolong the QTc interval. Since none of the current therapies work for every patient, a pharmacogenetic approach was used to identify genetic markers associated with increased response to iloperidone, suggesting a personalized therapeutic option for this drug. In addition, a long-term 4-week injectable formulation is being developed that may assist with patient compliance. Key development findings for iloperidone are presented here.

Thermal control of virulence factors in bacteria: A hot topic

Pathogenic bacteria sense environmental cues, including the local temperature, to control the production of key virulence factors. Thermal regulation can be achieved at the level of DNA, RNA or protein and although many virulence factors are subject to thermal regulation, the exact mechanisms of control are yet to be elucidated in many instances. Understanding how virulence factors are regulated by temperature presents a significant challenge, as gene expression and protein production are often influenced by complex regulatory networks involving multiple transcription factors in bacteria. Here we highlight some recent insights into thermal regulation of virulence in pathogenic bacteria. We focus on bacteria which cause disease in mammalian hosts, which are at a significantly higher temperature than the outside environment. We outline the mechanisms of thermal regulation and how understanding this fundamental aspect of the biology of bacteria has implications for pathogenesis and human health.

Bioanalysis of meningococcal vaccines

Meningococcal meningitis is feared because of the rapid onset of severe disease from mild symptoms and, therefore, is an important target for vaccine research. Five serogroups, defined by the structures of their capsular polysaccharides, are responsible for the vast majority of disease. Protection against four of these five serogroups can be obtained with polysaccharide or glycoconjugate vaccines, in which fragments of the capsular polysaccharides attached to a carrier protein generate anticarbohydrate immune responses, whilst protection against group B disease requires protein immunogens, often presented in vesicles containing outer membrane proteins. Glycoconjugate vaccines are now an established technology, but outer-membrane protein vaccines are still under development and present significant challenges. This review discusses physicochemical approaches to the characterization and quality control of these vaccines, as well as highlighting the problems and differences in vaccine design required for protection against different serogroups of the same species of pathogen.