Publications by authors named "Caroline Vipond"

21 Publications

  • Page 1 of 1

Factor H binding protein (fHbp)-mediated differential complement resistance of a serogroup C isolate from cerebrospinal fluid of a patient with invasive meningococcal disease.

Access Microbiol 2021 9;3(9):000255. Epub 2021 Sep 9.

Division of Bacteriology, National Institute for Biological Standards and Control (NIBSC), Blanche Lane, South Mimms, Potters Bar, Hertfordshire, EN6 3QG, UK.

During an outbreak of invasive meningococcal disease (IMD) at the University of Southampton, UK, in 1997, two serogroup C isolates were retrieved from a student ('Case'), who died of IMD, and a close contact ('Carrier') who, after mouth-to-mouth resuscitation on the deceased, did not contract the disease. Genomic comparison of the isolates demonstrated extensive nucleotide sequence identity, with differences identified in eight genes. Here, comparative proteomics was used to measure differential protein expression between the isolates and investigate whether the differences contributed to the clinical outcomes. A total of six proteins were differentially expressed: four proteins (methylcitrate synthase, PrpC; hypothetical integral membrane protein, Imp; fructose-1,6-bisphosphate aldolase, Fba; aldehyde dehydrogenase A, AldA) were upregulated in the Case isolate, while one protein (Type IV pilus-associated protein, PilC2) was downregulated. Peptides for factor H binding protein (fHbp), a major virulence factor and antigenic protein, were only detected in the Case, with a single base deletion (ΔT366) in the Carrier fHbp causing lack of its expression. Expression of fHbp resulted in an increased resistance of the Case isolate to complement-mediated killing in serum. Complementation of fHbp expression in the Carrier increased its serum resistance by approximately 8-fold. Moreover, a higher serum bactericidal antibody titre was seen for the Case isolate when using sera from mice immunized with Bexsero (GlaxoSmithKline), a vaccine containing fHbp as an antigenic component. This study highlights the role of fHbp in the differential complement resistance of the Case and the Carrier isolates. Expression of fHbp in the Case resulted in its increased survival in serum, possibly leading to active proliferation of the bacteria in blood and death of the student through IMD. Moreover, enhanced killing of the Case isolate by sera raised against an fHbp-containing vaccine, Bexsero, underlines the role and importance of fHbp in infection and immunity.
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http://dx.doi.org/10.1099/acmi.0.000255DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8549389PMC
September 2021

Development of a Monocyte Activation Test as an Alternative to the Rabbit Pyrogen Test for Mono- and Multi-Component GMMA-Based Vaccines.

Microorganisms 2021 Jun 24;9(7). Epub 2021 Jun 24.

The National Institute for Biological Standards and Control (NIBSC), South Mimms EN6 3QG, UK.

Generalised modules for membrane antigens (GMMA)-based vaccines comprise the outer membrane from genetically modified Gram-negative bacteria containing membrane proteins, phospholipids and lipopolysaccharides. Some lipoproteins and lipopolysaccharides are pyrogens; thus, GMMA-based vaccines are intrinsically pyrogenic. It is important to control the pyrogenic content of biological medicines, including vaccines, to prevent adverse reactions such as febrile responses. The rabbit pyrogen test (RPT) and bacterial endotoxin test (BET) are the most commonly employed safety assays used to detect pyrogens. However, both tests are tailored for detecting pyrogenic contaminants and have considerable limitations when measuring the pyrogen content of inherently pyrogenic products. We report the adaptation of the monocyte activation test (MAT) as an alternative to the RPT for monitoring the pyrogenicity of GMMA-based vaccines. The European Pharmacopoeia endorses three MAT methods (A-C). Of these, method C, the reference lot comparison test, was identified as the most suitable. This method was evaluated with different reference materials to ensure parallelism and consistency for a mono- and multi-component GMMA vaccine. We demonstrate the drug substance as a promising reference material for safety testing of the matched drug product. Our results support the implementation of MAT as an alternative to the RPT and use of the defined parameters can be extended to GMMA-based vaccines currently in development, aiding vaccine batch release.
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http://dx.doi.org/10.3390/microorganisms9071375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8306433PMC
June 2021

Understanding the reactogenicity of 4CMenB vaccine: Comparison of a novel and conventional method of assessing post-immunisation fever and correlation with pre-release in vitro pyrogen testing.

Vaccine 2020 11 24;38(49):7834-7841. Epub 2020 Oct 24.

Oxford Vaccine Group, Department of Paediatrics, University of Oxford, NIHR Oxford Biomedical Research Centre, United Kingdom.

Background: Better understanding of vaccine reactogenicity is crucial given its potential impact upon vaccine safety and acceptance. Here we report a comparison between conventional and novel (continuous) methods of monitoring temperature and evaluate any association between reactogenicity and the monocyte activation test (MAT) employed for testing four-component capsular group B meningococcal vaccine (4CMenB) batches prior to release for clinical use in Europe.

Methods: Healthy 7-12-week-old infants were randomised in two groups: group PCV13 2 + 1 (received pneumococcal conjugate vaccine 13 valent (PCV13) at 2, 4 and 12 months) and group PCV13 1 + 1 (received reduced schedule at 3 and 12 months). In both, infants received the remaining immunisations as per UK national schedule (including 4CMenB at 2, 4 and 12 months of age). Fever was measured for the first 24 h after immunisations using an axillary thermometer and with a wireless continuous temperature monitoring device (iButton®). To measure the relative pyrogenicity of individual 4CMenB batches, MAT was performed according to Ph. Eu. chapter 2.6.30 method C using PBMCs with IL-6 readout.

Results: Fever rates detected by the iButton® ranged from 28.7% to 76.5% and from 46.6% to 71.1% in group PCV13 2 + 1 and PCV13 1 + 1 respectively, across all study visits. The iButton® recorded a higher number of fever episodes when compared with axillary measurements in both groups (range of axillary temperature fevers; group PCV13 2 + 1: 6.7%-38%; group PCV13 1 + 1: 11.4%-37.1%). An agreement between the two methods was between 0.39 and 0.36 (p < 0.001) at 8 h' time-point post primary immunisations. No correlation was found between MAT scores and fever rates, or other reported adverse events.

Conclusions: It is likely that conventional, intermittent, fever measurements underestimates fever rates following immunisation. 4CMenB MAT scores didn't predict reactogenicity, providing reassurance that vaccine batches with the highest acceptable pyrogen level are not associated with an increase in adverse events. Clinicaltrials.gov identifier: NCT02482636.
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http://dx.doi.org/10.1016/j.vaccine.2020.10.023DOI Listing
November 2020

Measurement of surface protein antigens, PorA and PorB, in Bexsero vaccine using quantitative mass spectrometry.

Vaccine 2020 02 12;38(6):1431-1435. Epub 2019 Dec 12.

National Institute for Biological Standards and Control (NIBSC), Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom.

Bexsero is a multivalent vaccine containing outer membrane vesicles (OMV) derived from Neisseria meningitidis group B strain NZ98/254 and three recombinant meningococcal proteins, Neisserial adhesin A, Heparin binding antigen and factor H binding protein. OMV production relies on the growth of large-scale cultures of N. meningitidis under controlled conditions. Changes to environmental factors, such as temperature, pH, nutrient availability and trace elements, can impact the growth rate of the meningococcus. Furthermore outer membrane expression levels vary in response to the environmental milieu, thus any changes in environmental conditions can result in changes in OMV protein content. This makes consistent production of OMVs challenging and the ability to measure the protein content of the final product is desirable to ensure product quality. The aim of this work was to develop a mass spectrometry (MS) method for measuring the porin proteins and to evaluate this approach for assessing the batch consistency of Bexsero vaccine. Using isotope dilution MS, we measured the PorA and PorB content in 75 lots of Bexsero vaccine. PorA ranged from 4.0 to 5.95 μg/dose with an average of 4.8 μg/dose. PorB ranged from 5.4 to 8.7 μg/dose with an average of 6.5 μg/dose. This is the first description of the quantitative characterisation of adjuvanted Bexsero vaccine drug product at the final stage of the production process, once the aluminium adjuvanted vaccine has been packaged into syringes, to assess manufacturing consistency. The significance of our findings to quality control in the future is discussed.
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http://dx.doi.org/10.1016/j.vaccine.2019.11.082DOI Listing
February 2020

Evaluation of the monocyte activation test for the safety testing of meningococcal B vaccine Bexsero: A collaborative study.

Vaccine 2019 06 10;37(29):3761-3769. Epub 2018 Dec 10.

Medicines and Healthcare Regulatory Agency - National Institute for Biological Standards and Control, South Mimms, Potters Bar, Herts EN6 3QG, UK.

The aim of this collaborative study was to evaluate the robustness of the monocyte activation test (MAT) for quantifying the pyrogenic content in the outer membrane vesicle (OMV)-containing vaccine Bexsero: the first meningococcal B vaccine to be licenced. We analysed datasets from 9 laboratories covering 15 test systems for 3 batches of Bexsero with higher, equivalent and lower activity relative to a reference lot in the MAT. Activity was measured in terms of relative pyrogen units (RPU) based on European Pharmacopoeia (Ph. Eur.) MAT Chapter 2.6.30 Method C: Reference Lot Comparison Test. We report that all 15 test systems were consistent in that they showed sample A to be the most active in the MAT; that 13 of 15 test systems had an accuracy of more than 80% and an overall geometric mean RPU of 1.03 with lower and upper 95% confidence limits of 0.97 and 1.09 respectively for a sample with an expected value of 1.00 RPU. We also report larger variability in the results for test systems involving cells from individual blood donations for sample A suggesting that there could be donor to donor differences in sensitivity to the vaccine constituents responsible for the higher activity of this batch. Overall, the consistency and accuracy of the MAT was remarkable given the range of test systems used by participants, all of which are permitted by the Ph. Eur. General MAT Chapter. This is important given the limitations of the rabbit pyrogen test for the control of pyrogenicity in general and particularly with products with intrinsic pyrogenicity such as Bexsero.
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http://dx.doi.org/10.1016/j.vaccine.2018.05.073DOI Listing
June 2019

Development and validation of a monocyte activation test for the control/safety testing of an OMV-based meningococcal B vaccine.

Vaccine 2019 06 10;37(29):3747-3753. Epub 2018 Dec 10.

Department of Biotherapeutics, The National Institute for Biological Standards and Control, Blanche Lane, Potters Bar EN6 3QG, UK.

It is imperative to ensure biological products are free of contaminating pyrogenic material prior to administration to patients. Historically the rabbit pyrogen test (RPT) was used to screen for such contamination in medicines for intravenous delivery. This test was adapted for use to screen vaccines. However, some, including meningococcal vaccines containing outer membrane vesicles, are intrinsically pyrogenic. Indeed, this is the case for Bexsero which contains relatively high levels of endotoxin and other potential pyrogens such as lipoproteins and porins. The RPT proved a difficult method for measuring the pyrogenic content of Bexsero and differences between laboratories in different countries made repeat testing at the control laboratories problematic resulting in batches being wrongly identified as unsafe. At NIBSC a monocyte activation test (MAT) was adapted and validated as an alternative. This required setting of a specification in-house and deciding on a decisional procedure using multiple donors, allowing batches equally pyrogenic or less, than those batches shown to be safe in a clinical trial, to be certified as safe. The resulting format was a reference comparison method with an upper limit of 1.8 relative pyrogen units (RPU). The batch passed if an initial four donors had a response equal to or less than 1.8 RPU, if one donor is above this limit the batch was tested in a further four donors and seven of the eight must be equal to or below 1.8 RPU. If two donors have a response greater than 1.8 the batch failed.
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http://dx.doi.org/10.1016/j.vaccine.2018.06.038DOI Listing
June 2019

Typing complex meningococcal vaccines to understand diversity and population structure of key vaccine antigens.

Wellcome Open Res 2018 19;3:151. Epub 2019 Mar 19.

Department of Zoology, University of Oxford, Oxford, OX1 3SY, UK.

Protein-conjugate capsular polysaccharide vaccines can potentially control invasive meningococcal disease (IMD) caused by five (A, C, W, X, Y) of the six IMD-associated serogroups.  Concerns raised by immunological similarity of the serogroup B capsule to human neural cell carbohydrates, meant that 'serogroup B substitute' vaccines target more variable subcapsular protein antigens.  A successful approach using outer membrane vesicles (OMVs) as major vaccine components had limited strain coverage. In 4CMenB (Bexsero ), recombinant proteins have been added to ameliorate this problem.   Scalable, portable, genomic techniques were used to investigate the Bexsero OMV protein diversity in meningococcal populations. Shotgun proteomics identified 461 proteins in the OMV, defining a complex proteome. Amino acid sequences for the 24 proteins most likely to be involved in cross-protective immune responses were catalogued within the PubMLST.org/neisseria database using a novel OMV peptide Typing (OMVT) scheme. Among these proteins there was variation in the extent of diversity and association with meningococcal lineages, identified as clonal complexes (ccs), ranging from the most conserved peptides (FbpA, NEISp0578, and putative periplasmic protein, NEISp1063) to the most diverse (TbpA, NEISp1690).  There were 1752 unique OMVTs identified amongst 2492/3506 isolates examined by whole-genome sequencing (WGS). These OMVTs were grouped into clusters (sharing ≥18 identical OMVT peptides), with 45.3% of isolates assigned to one of 27 OMVT clusters. OMVTs and OMVT clusters were strongly associated with cc, genogroup, and Bexsero antigen variants, demonstrating that combinations of OMV proteins exist in discrete, non-overlapping combinations associated with genogroup and Bexsero Antigen Sequence Type. This highly structured population of IMD-associated meningococci is consistent with strain structure models invoking host immune and/or metabolic selection. The OMVT scheme facilitates region-specific WGS investigation of meningococcal diversity and is an open-access, portable tool with applications for vaccine development, especially in the choice of antigen combinations, assessment and implementation.
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http://dx.doi.org/10.12688/wellcomeopenres.14859.2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6338130PMC
March 2019

Safety of multicomponent meningococcal group B vaccine (4CMenB) in routine infant immunisation in the UK: a prospective surveillance study.

Lancet Child Adolesc Health 2018 06 25;2(6):395-403. Epub 2018 Apr 25.

Division of Bacteriology, National Institute for Biological Standards and Control, Hertfordshire, UK.

Background: Safety data for the multicomponent meningococcal group B vaccine (4CMenB) has so far been limited to experience from clinical trials and isolated local outbreaks. Since the UK is the first country to implement a nationwide routine immunisation programme with 4CMenB (at age 8 weeks, 16 weeks, and then 1 year), we aimed to assess the safety of 4CMenB in this setting.

Methods: In this prospective surveillance study, we assessed suspected adverse reactions of 4CMenB in children up to age 18 months reported in the UK Yellow Card Scheme and primary care records extracted from the Clinical Practice Research Datalink (CPRD). We proactively assessed reports of fever, local reactions, Kawasaki disease, seizures, and sudden death, and compared the number of spontaneous reports with the expected number of events based on background incidence and the number of children vaccinated. We also identified any unexpected adverse reactions and estimated compliance with subsequent doses of routine vaccinations.

Findings: From Sept 1, 2015, to May 31, 2017, approximately 1·29 million children aged 2-18 months received about a combined 3 million doses of 4CMenB. 902 reports of suspected adverse reactions were received through the UK Yellow Card Scheme, of which 366 (41%) were related to local reactions and 364 (40%) related to fever. The only unexpected finding was that 160 reports of local reactions described a persistent nodule at the site of injection, usually without other local symptoms. There were 55 (6%) reports of seizures, with an age-adjusted observed-to-expected ratio of 0·13 (95% CI 0·10-0·17). Ecological analyses found similar rates of seizures within 7 days of routine immunisation in the periods before and after 4CMenB introduction, with incidence rate ratios of 1·30 (95% CI 0·56-3·00) at age 2 months, 1·53 (0·49-4·74) at age 4 months, and 1·26 (0·69-2·32) at age 12 months. Of the 902 reports, three (<1%) were of Kawasaki disease (observed-to-expected ratio 1·40, 95% CI 0·29-4·08) and three (<1%) of sudden infant death syndrome within 3 days of vaccination in children aged 2-4 months (0·44, 0·12-1·14). Analysis of routine immunisations recorded in CPRD found that 11 602 (95·1%) of 12 199 children had received the second dose of 4CMenB by 26 weeks of age, 1793 (84·7%) of 2117 had received the third dose by 62 weeks of age, and 4CMenB introduction had not reduced compliance with doses of other routine vaccinations.

Interpretation: We found no significant safety concerns after widespread use of 4CMenB in UK infants, and the vaccine appears to have been well accepted by parents. However, it is important to continue monitoring the safety and long-term effect of the immunisation programme in the UK to further characterise the reported suspected adverse reactions.

Funding: None.
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http://dx.doi.org/10.1016/S2352-4642(18)30103-2DOI Listing
June 2018

Evaluation of candidate international standards for meningococcal serogroups A and X polysaccharide.

Biologicals 2017 May 5;47:33-45. Epub 2017 Apr 5.

Division of Bacteriology, National Institute for Biological Standards and Control (NIBSC), Blanche Lane, Potters Bar, Hertfordshire EN6 3QG, UK.

Polysaccharide (PS) based meningococcal vaccines are primarily evaluated by physicochemical methods to ensure batches are consistently manufactured. As PS content is determined by different methods across numerous laboratories, there is a need for International Standards (IS) to calibrate the assays. Following the successful introduction of the WHO Meningococcal group C (MenC) IS in 2011, NIBSC initiated projects to prepare similar standards for groups A, W, Y and X (MenA/W/Y/X) to standardise all meningococcal- PS based vaccines. On the basis of results from a collaborative study to evaluate preparations of MenA and MenX PS, both were established by the WHO Expert Committee on Biological Standardization in Oct 2015 as; the First WHO International Standard for the Meningococcal Group A polysaccharide with a content of 0.845 ± 0.043 mg MenA PS per ampoule (expanded uncertainty with coverage factor of k=2.45 corresponding to a 95% level of confidence); the First WHO International Standard for the Meningococcal Group X polysaccharide with a content of 0.776 ± 0.089 mg MenX PS per ampoule (expanded uncertainty with coverage factor of k=2.45), as determined by quantitative NMR. The standards are available from NIBSC, who act as guardians and distributors of the material under the auspices of WHO.
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http://dx.doi.org/10.1016/j.biologicals.2017.03.001DOI Listing
May 2017

Limitations of the rabbit pyrogen test for assessing meningococcal OMV based vaccines.

ALTEX 2016 2;33(1):47-53. Epub 2015 Dec 2.

Department of Bacteriology, National Institute of Biological Standards and Control, South Mimms, Potter Bar, UK.

The rabbit pyrogen test was developed in the early 1900's to detect contaminating pyrogens in parenteral medicines. Since its conception alternative methods with improved sensitivity, relevancy and which are ethically more acceptable have been developed. However, the test is a current Pharmacopeial method and is used to evaluate the pyrogen content of some vaccines. In this article the limitations and pitfalls of using the test to measure pyrogenicity of vaccines containing outer membrane vesicles are described. The method is unsuitable as a safety test for these products due to the high levels of endotoxin present in the vaccine which generate a pyrogenic response in rabbits when delivered intravenously without any dilution. Its use as a consistency test is also ambiguous as the test gives a qualitative rather than quantitative response and the rabbit models are highly variable. In addition there is evidence that measuring the temperature rise of the animals over three hours does not capture the maximum fever response. Finally the article considers the use of alternative methods and the validity of animal models when applying a consistency based approach for assessing the quality of licensed products.
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http://dx.doi.org/10.14573/altex.1509291DOI Listing
October 2016

FetA Antibodies Induced by an Outer Membrane Vesicle Vaccine Derived from a Serogroup B Meningococcal Isolate with Constitutive FetA Expression.

PLoS One 2015 14;10(10):e0140345. Epub 2015 Oct 14.

National Institute of Biological Standards and Control, South Mimms, Potters Bar, United Kingdom.

Invasive meningococcal disease causes over 3500 cases each year in Europe, with particularly high incidence among young children. Among serogroup B meningococci, which cause most of the cases, high diversity in the outer membrane proteins (OMPs) is observed in endemic situations; however, comprehensive molecular epidemiological data are available for the diversity and distribution of the OMPs PorA and FetA and these can be used to rationally design a vaccine with high coverage of the case isolates. The aim of this study was to determine whether outer membrane vesicles (OMVs) derived from an isolate with constitutive FetA expression (MenPF-1 vaccine) could be used to induce antibodies against both the PorA and FetA antigens. The immunogenicity of various dose levels and number of doses was evaluated in mice and rabbits, and IgG antibody responses tested against OMVs and recombinant PorA and FetA proteins. A panel of four isogenic mutants was generated and used to evaluate the relative ability of the vaccine to induce serum bactericidal activity (SBA) against FetA and PorA. Sera from mice were tested in SBA against the four target strains. Results demonstrated that the MenPF-1 OMVs were immunogenic against PorA and FetA in both animal models. Furthermore, the murine antibodies induced were bactericidal against isogenic mutant strains, suggesting that antibodies to both PorA and FetA were functional. The data presented indicate that the MenPF-1 vaccine is a suitable formulation for presenting PorA and FetA OMPs in order to induce bactericidal antibodies, and that proceeding to a Phase I clinical trial with this vaccine candidate is justified.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0140345PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4605655PMC
June 2016

An OMV Vaccine Derived from a Capsular Group B Meningococcus with Constitutive FetA Expression: Preclinical Evaluation of Immunogenicity and Toxicity.

PLoS One 2015 21;10(9):e0134353. Epub 2015 Sep 21.

Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.

Following the introduction of effective protein-polysaccharide conjugate vaccines against capsular group C meningococcal disease in Europe, meningococci of capsular group B remain a major cause of death and can result in debilitating sequelae. The outer membrane proteins PorA and FetA have previously been shown to induce bactericidal antibodies in humans. Despite considerable antigenic variation among PorA and FetA OMPs in meningococci, systematic molecular epidemiological studies revealed this variation is highly structured so that a limited repertoire of antigenic types is congruent with the hyperinvasive meningococcal lineages that have caused most of the meningococcal disease in Europe in recent decades. Here we describe the development of a prototype vaccine against capsular group B meningococcal infection based on a N. meningitidis isolate genetically engineered to have constitutive expression of the outer membrane protein FetA. Deoxycholate outer membrane vesicles (dOMVs) extracted from cells cultivated in modified Frantz medium contained 21.8% PorA protein, 7.7% FetA protein and 0.03 μg LPS per μg protein (3%). The antibody response to the vaccine was tested in three mouse strains and the toxicological profile of the vaccine was tested in New Zealand white rabbits. Administration of the vaccine, MenPF-1, when given by intramuscular injection on 4 occasions over a 9 week period, was well tolerated in rabbits up to 50 μg/dose, with no evidence of systemic toxicity. These data indicated that the MenPF-1 vaccine had a toxicological profile suitable for testing in a phase I clinical trial.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134353PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4577077PMC
May 2016

Evaluation of a candidate International Standard for Meningococcal Group C polysaccharide.

Biologicals 2012 Sep 22;40(5):353-63. Epub 2012 May 22.

Division of Bacteriology, NIBSC, Blanche Lane, Potters Bar, Hertfordshire EN6 3QG, UK.

Meningococcal group C (MenC) plain polysaccharide (PS) and conjugate vaccines are primarily evaluated by physicochemical methods to ensure that batches are consistently manufactured. As different assays are employed to quantify the MenC PS content of final formulations and bulk intermediaries, there is a need for an International MenC PS Standard to calibrate internal references used in the different laboratories. Twelve laboratories from nine different countries participated in a collaborative study to determine the MenC PS content of a candidate International Standard MenC PS preparation (08/214) and to assess its suitability. On the basis of the results from this study the candidate standard 08/214 was established as an International Standard for the quantification of MenC PS content in vaccines and components. It has a content of 1.192 ± 0.192 mg MenC PS/ampoule (expanded uncertainty with coverage factor of k = 2.365 corresponding to a 95% level of confidence), as determined by the resorcinol assays carried out by eight of the participating laboratories. The standard is available from The National Institute of Biological Standards and Control who act as guardians and distributors of the material under the auspices of WHO.
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http://dx.doi.org/10.1016/j.biologicals.2012.03.003DOI Listing
September 2012

History of meningococcal vaccines and their serological correlates of protection.

Vaccine 2012 May;30 Suppl 2:B10-7

National Institute of Biological Standards and Control, Potters Bar, Hertfordshire EN6 3QG, United Kingdom.

For over a hundred years Neisseria meningitidis has been known to be one of the major causes of bacterial meningitis. However, effective vaccines were not developed until the latter part of the 20th century. The first of these were based on purified high molecular weight capsular polysaccharides and more recently the development of glycoconjugate vaccines has made paediatric immunisation programmes possible. The prevention of group B meningococcal disease has remained a challenge throughout this period. This review charts the history of the development of meningococcal vaccines and the importance of serological correlates of protection in their evaluation.
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http://dx.doi.org/10.1016/j.vaccine.2011.12.060DOI Listing
May 2012

The effect of iron availability on transcription of the Neisseria meningitidis fHbp gene varies among clonal complexes.

Microbiology (Reading) 2012 Apr 12;158(Pt 4):869-876. Epub 2012 Jan 12.

National Institute for Biological Standards and Control, Blanche Lane, Potters Bar, Hertfordshire EN6 3QG, UK.

Factor H binding protein (fHbp) is a major antigenic component of novel vaccines designed to protect against meningococcal disease. Prediction of the potential coverage of these vaccines is difficult, as fHbp is antigenically variable and levels of expression differ among isolates. Transcriptional regulation of the fHbp gene is poorly understood, although evidence suggests that oxygen availability is involved. In this study iron accessibility was found to affect fHbp transcription. However, regulation differed among meningococcal clonal complexes (ccs). For the majority of isolates, increased iron concentrations upregulated transcription. This effect was enhanced by the presence of a 181 bp insertion element upstream of fHbp, associated with isolates belonging to cc4 and cc5. Conversely, meningococci belonging to cc32 showed iron-repressed control of fHbp, as regulation was dominated by cotranscription with the iron-repressed upstream gene cbbA. These results highlight the complexity of fHbp regulation and demonstrate that control of transcription can vary among genetic lineages.
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http://dx.doi.org/10.1099/mic.0.054957-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949423PMC
April 2012

Variation in the Neisseria meningitidis FadL-like protein: an evolutionary model for a relatively low-abundance surface antigen.

Microbiology (Reading) 2010 Dec 3;156(Pt 12):3596-3608. Epub 2010 Sep 3.

Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.

The molecular diversity of a novel Neisseria meningitidis antigen, encoded by the ORF NMB0088 of MC58 (FadL-like protein), was assessed in a panel of 64 diverse meningococcal strains. The panel consisted of strains belonging to different serogroups, serotypes, serosubtypes and MLST sequence types, of different clinical sources, years and countries of isolation. Based on the sequence variability of the protein, the FadL-like protein has been divided into four variant groups in this species. Antigen variants were associated with specific serogroups and MLST clonal complexes. Maximum-likelihood analyses were used to determine the relationships among sequences and to compare the selection pressures acting on the encoded protein. Furthermore, a model of population genetics and molecular evolution was used to detect natural selection in DNA sequences using the non-synonymous : synonymous substitution (d(N) : d(S)) ratio. The meningococcal sequences were also compared with those of the related surface protein in non-pathogenic commensal Neisseria species to investigate potential horizontal gene transfer. The N. meningitidis fadL gene was subject to only weak positive selection pressure and was less diverse than meningococcal major outer-membrane proteins. The majority of the variability in fadL was due to recombination among existing alleles from the same or related species that resulted in a discrete mosaic structure in the meningococcal population. In general, the population structuring observed based on the FadL-like membrane protein indicates that it is under intermediate immune selection. However, the emergence of a new subvariant within the hyperinvasive lineages demonstrates the phenotypic adaptability of N. meningitidis, probably in response to selective pressure.
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http://dx.doi.org/10.1099/mic.0.043182-0DOI Listing
December 2010

Characterization of meningococcal serogroup B outer membrane vesicle vaccines from strain 44/76 after growth in different media.

Vaccine 2010 Apr 25;28(18):3211-8. Epub 2010 Feb 25.

National Institute for Biological Standards and Control, Health Protection Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.

In this study, we evaluated the effect of the growth medium on the composition and immunogenicity of meningococcal outer membrane vesicle (OMV) vaccines after cultivation of the Norwegian serogroup B 44/76 vaccine strain in either Frantz' or modified Catlin-6 media (MC.6M). Differential proteomic analysis revealed that 97% of the OMV proteins maintained the same levels in the two preparations. However, a number of differentially expressed proteins, including TdfH, OpcA, OMP NMB0088, hypothetical NMB2134, lipoprotein NMB1126/1164 and NspA, increased significantly in OMVs produced from bacteria grown in the MC.6M. Together with increased lipopolysaccharide levels, the increased expression of these proteins was associated with significantly higher serum bactericidal titres in mice immunized with the MC.6M OMV vaccine. The high resolution two-dimensional separation of the OMVs on a large-format gel across a pH range of 3-11 resolved around 2000 protein spots from which 75 proteins were identified by mass spectrometry.
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http://dx.doi.org/10.1016/j.vaccine.2010.02.023DOI Listing
April 2010

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

Hum Vaccin 2008 Jan-Feb;4(1):23-30. Epub 2007 Jul 29.

Health Protection Agency, Centre for Emergency Preparedness and Response, Porton Down, Salisbury, UK.

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 immunized 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 immunized 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, suggestingthat this may did mediate opsonophagocytosis, suggesting that this may be a mechanism by which this vaccine protects in a mouse model of meningococcal bacteraemia.
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http://dx.doi.org/10.4161/hv.4.1.4806DOI Listing
August 2008

Exploring the proteome of meningococcal outer membrane vesicle vaccines.

Proteomics Clin Appl 2007 Sep 17;1(9):1198-210. Epub 2007 Aug 17.

Laboratory of Molecular Structure, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire, UK.

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.
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http://dx.doi.org/10.1002/prca.200700204DOI Listing
September 2007

Characterization of the protein content of a meningococcal outer membrane vesicle vaccine by polyacrylamide gel electrophoresis and mass spectrometry.

Hum Vaccin 2005 Mar-Apr;1(2):80-4. Epub 2005 Mar 2.

Division of Bacteriology, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, UK.

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.
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http://dx.doi.org/10.4161/hv.1.2.1651DOI Listing
October 2006

Proteomic analysis of a meningococcal outer membrane vesicle vaccine prepared from the group B strain NZ98/254.

Proteomics 2006 Jun;6(11):3400-13

Department of Bacteriology, National Institute for Biological Standards and Control, South Mimms, Hertfordshire, UK.

In the absence of a suitable carbohydrate-based vaccine, outer membrane vesicle (OMV) vaccines have been used to disrupt outbreaks of serogroup B meningococcal disease for more than 20 years. Proteomic technology provides physical methods with the potential to assess the composition and consistency of these complex vaccines. 2-DE, combined with MS, were used to generate a proteome map of an OMV vaccine, developed to disrupt a long-running outbreak of group B disease in New Zealand. Seventy four spots from the protein map were identified including the outer membrane protein (OMP) antigens: PorA, PorB, RmpM and OpcA. Protein identification indicates that, in addition to OMPs, OMV vaccines contain periplasmic, membrane-associated and cytoplasmic proteins. 2-D-DIGE technology highlighted differences between preclinical development batches of vaccines from two different manufacturers.
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http://dx.doi.org/10.1002/pmic.200500821DOI Listing
June 2006
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