[Show abstract][Hide abstract] ABSTRACT: Background: Current guidelines do not clearly outline when assent should be attained from paediatric research participants, nor do they detail the necessary elements of the assent process. This stems from the fact that the fundamental justification behind the concept of assent is misunderstood. In this paper, we critically assess three widespread ethical arguments used for assent: children's rights, the best interests of the child, and respect for a child's developing autonomy. We then outline a newly-developed two-fold justification for the assent process: respect for the parent's pedagogical role in teaching their child to become an autonomous being and respect for the child's moral worth. Discussion: We argue that the ethical grounding for the involvement of young children in medical decision-making does not stem from children's rights, the principle of best interests, or respect for developing autonomy. An alternative strategy is to examine the original motivation to engage with the child. In paediatric settings there are two obligations on the researcher: an obligation to the parents who are responsible for determining when and under what circumstances the child develops his capacity for autonomy and reasoning, and an obligation to the child himself. There is an important distinction between respecting a decision and encouraging a decision. This paper illustrates that the process of assent is an important way in which respect for the child as an individual can be demonstrated, however, the value lies not in the child's response but the fact that his views were solicited in the first place. Summary: This paper demonstrates that the common justifications for the process of assent are incomplete. Assent should be understood as playing a pedagogical role for the child, helping to teach him how specific decisions are made and therefore helping him to become a better decision-maker. How the researcher engages with the child supports his obligation to the child's parents, yet why the researcher engages with the child stems from the child's moral worth. Treating a child as having moral worth need not mean doing what they say but it may mean listening, considering, engaging or involving them in the decision.
[Show abstract][Hide abstract] ABSTRACT: A randomized controlled trial in Fiji examined the immunogenicity and effect on nasopharyngeal carriage after 0, 1, 2, or 3 doses of 7-valent pneumococcal conjugate vaccine (PCV7; Prevnar) in infancy followed by 23-valent pneumococcal polysaccharide vaccine (23vPPV; Pneumovax) at 12 months of age. At 18 months of age, children given 23vPPV exhibited immune hyporesponsiveness to a micro-23vPPV (20%) challenge dose in terms of serotype-specific IgG and opsonophagocytosis, while 23vPPV had no effect on vaccine-type carriage.
This follow-up study examined the long-term effect of the 12-month 23vPPV dose by evaluating the immune response to 13-valent pneumococcal conjugate vaccine (PCV13) administration 4 to 5 years later.
Blood samples from 194 children (now 5-7 years old) were taken before and 28 days after PCV13 booster immunization. Nasopharyngeal swabs were taken before PCV13 immunization. We measured levels of serotype-specific IgG to all 13 vaccine serotypes, opsonophagocytosis for 8 vaccine serotypes, and memory B-cell responses for 18 serotypes before and after PCV13 immunization.
Paired samples were obtained from 185 children. There were no significant differences in the serotype-specific IgG, opsonophagocytosis, or memory B-cell response at either time point between children who did or did not receive 23vPPV at 12 months of age. Nasopharyngeal carriage of PCV7 and 23vPPV serotypes was similar among the groups. Priming with 1, 2, or 3 PCV7 doses during infancy did not affect serotype-specific immunity or carriage.
Immune hyporesponsiveness induced by 23vPPV in toddlers does not appear to be sustained among preschool children in this context and does not affect the pneumococcal carriage rate in this age group.
No preview · Article · Jan 2016 · The Journal of allergy and clinical immunology
[Show abstract][Hide abstract] ABSTRACT: Opa proteins are major proteins involved in meningococcal colonization of the nasopharynx and immune interactions. Opa proteins undergo phase variation (PV) due to the presence of the 5′-CTCTT-3′ coding repeat (CR) sequence. The dynamics of PV of meningococcal Opa proteins is unknown. Opa PV, including the effect of transformation on PV, was assessed using a panel of Opa-deficient strains of Neisseria meningitidis. Analysis of Opa expression from UK disease-causing isolates was undertaken. Different opa genes demonstrated variable rates of PV, between 6.4 ×10–4 and 6.9 ×10–3 per cell per generation. opa genes with a longer CR tract had a higher rate of PV (r
2=0.77, p=0.1212). Bacterial transformation resulted in a 180-fold increase in PV rate. The majority of opa genes in UK disease isolates (315/463, 68.0%) were in the ‘on’ phase, suggesting the importance of Opa proteins during invasive disease. These data provide valuable information for the first time regarding meningococcal Opa PV. The presence of Opa PV in meningococcal populations and high expression of Opa among invasive strains likely indicates the importance of this protein in bacterial colonization in the human nasopharynx. These findings have potential implications for development of vaccines derived from meningococcal outer membranes.
No preview · Article · Jan 2016 · Journal of Biosciences
[Show abstract][Hide abstract] ABSTRACT: Background:
A serogroup B meningococcal vaccine (4CMenB) is licensed for infant use in countries including Canada, Australia and those of the European Union. Data on serum bactericidal antibody (hSBA) waning and the ideal timing of a 'toddler' booster dose are essential to optimize vaccine utilization.
An open-labeled, multicenter phase-2b follow-on European study conducted from 2009 to 2012. Participants previously receiving 4CMenB with routine vaccines at 2,4,6 or 2,3,4 months (246Con and 234Con) or at 2,4,6 months intercalated with routine vaccines (246Int) received a booster dose at 12, 18 or 24 months. 4CMenB-naïve 'Control' participants aged 12, 18 or 24 months received two doses of 4CMenB two months apart.
1588 participants were recruited. At 12 months, prior to any booster doses, the proportions with hSBA titers ≥ 1:5 for strain 44/76-SL (testing vaccine component fHBP) were 73% (120/165) for the '246Con' group, 85% (125/147) for '246Int', 57% (51/90) for '234Con' and 13% (26/199) for Controls. For strain 5/99 (NadA) proportions were ≥ 96% (all 4CMenB-recipients) and 1% (Controls). For strain NZ98/254 (PorA) these were 18-35% (4CMenB-recipients) and 1% (Controls). By 24 months, 4CMenB-recipient proportions were 13%-22% (44/76-SL), 82%-94% (5/99) and 7-13% (NZ98/254) and in Controls " 4%. Following a 12-month booster-dose ≥ 95% of previously immunized participants had titers ≥1:5 (all strains).
A 4CMenB booster-dose can overcome waning hSBA titers after early-infant immunization. Administration at 12 months could help to maintain immunity during an age of high risk, and the persistence of this response requires further study.
No preview · Article · Jan 2016 · The Pediatric Infectious Disease Journal
[Show abstract][Hide abstract] ABSTRACT: The dynamics and molecular mechanisms underlying vaccine immunity in early childhood remain poorly understood. Here we applied systems approaches to investigate the innate and adaptive responses to trivalent inactivated influenza vaccine (TIV) and MF59-adjuvanted TIV (ATIV) in 90 14- to 24-mo-old healthy children. MF59 enhanced the magnitude and kinetics of serum antibody titers following vaccination, and induced a greater frequency of vaccine specific, multicytokine-producing CD4(+) T cells. Compared with transcriptional responses to TIV vaccination previously reported in adults, responses to TIV in infants were markedly attenuated, limited to genes regulating antiviral and antigen presentation pathways, and observed only in a subset of vaccinees. In contrast, transcriptional responses to ATIV boost were more homogenous and robust. Interestingly, a day 1 gene signature characteristic of the innate response (antiviral IFN genes, dendritic cell, and monocyte responses) correlated with hemagglutination at day 28. These findings demonstrate that MF59 enhances the magnitude, kinetics, and consistency of the innate and adaptive response to vaccination with the seasonal influenza vaccine during early childhood, and identify potential molecular correlates of antibody responses.
Full-text · Article · Jan 2016 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: In 2015, the UK became the first country in the world to have a comprehensive routine meningococcal vaccine programme targeting all of the main capsular groups of N. meningitidis. 1 An infant vaccine programme against meningococcal capsular group B Neisseria meningitidis (MenB) was launched from 1st September with an aim to reduce endemic MenB disease in early childhood. On 1st August 2015, an adolescent programme against groups A, C, W and Y meningococci (MenACWY) was rolled out to halt a growing outbreak of capsular group W disease (MenW) caused by a hypervirulent clone of N. meningitidis, in addition to maintaining control against MenC disease provided by the current adolescent programme. 2.
Full-text · Article · Dec 2015 · Archives of Disease in Childhood
[Show abstract][Hide abstract] ABSTRACT: Respiratory syncytial virus (RSV) infection is the most important cause of hospitalization in infants and is one of the leading global causes of infant mortality and as such its prevention through vaccination is a public health priority. While essential for the successful implementation of vaccine programs, there remains a paucity of data on the epidemiology of the virus in different settings and age groups and limited knowledge about virus transmission and the health-care costs of the disease. Such data are now needed to populate health economic models and to inform optimal approaches to disease control through vaccination.
Full-text · Article · Dec 2015 · Expert Review of Vaccines
[Show abstract][Hide abstract] ABSTRACT: We report a 3-year-old boy with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis with a typical syndrome of movement disorder and encephalopathy and evidence of herpes simplex virus (HSV) type 1 infection on brain biopsy. HSV type 1 infection and anti-NMDAR encephalitis are temporally linked in some cases: this case suggests that prodromal HSV type-1 infection may be clinically subtle, and easily missed.
No preview · Article · Dec 2015 · The Pediatric Infectious Disease Journal
[Show abstract][Hide abstract] ABSTRACT: Editorial summary
High-throughput technologies applied to the analysis of vaccine responses are likely to reveal the mechanisms responsible for vaccine-induced protection, aid understanding of vaccine safety and help accelerate vaccine development and clinical trials.
[Show abstract][Hide abstract] ABSTRACT: The Raman scattering D-peak in graphene is spatially localised in close proximity to defects. Here, we demonstrate the capability of tip-enhanced Raman spectroscopy (TERS) to probe individual point defects, even for a graphene layer with an extremely low defect density. This is of practical interest for future graphene electronic devices. The measured TERS spectra enable a direct determination of the average inter-defect distance within the graphene sheet. Analysis of the TERS enhancement factor of the graphene Raman peaks highlights the preferential enhancement and symmetry-dependent selectivity of the D-peak intensity caused by zero-dimensional Raman scatterers.
[Show abstract][Hide abstract] ABSTRACT: Generating a diverse B cell immunoglobulin repertoire is essential for protection against infection. The repertoire in humans can now be comprehensively measured by high-throughput sequencing. Using hepatitis B vaccination as a model, we determined how the total immunoglobulin sequence repertoire changes following antigen exposure in humans, and compared this to sequences from vaccine-specific sorted cells. Clonal sequence expansions were seen 7days after vaccination, which correlated with vaccine-specific plasma cell numbers. These expansions caused an increase in mutation, and a decrease in diversity and complementarity-determining region 3 sequence length in the repertoire. We also saw an increase in sequence convergence between participants 14 and 21days after vaccination, coinciding with an increase of vaccine-specific memory cells. These features allowed development of a model for in silico enrichment of vaccine-specific sequences from the total repertoire. Identifying antigen-specific sequences from total repertoire data could aid our understanding B cell driven immunity, and be used for disease diagnostics and vaccine evaluation.
[Show abstract][Hide abstract] ABSTRACT: Invasive Salmonella disease in Africa is a major public health concern. With evidence of the transcontinental spread of the Salmonella Typhi H58 haplotype, improved estimates of the burden of infection and understanding of the complex interplay of factors
affecting disease transmission are needed to assist with efforts aimed at disease control. In addition to Salmonella Typhi, invasive nontyphoidal Salmonella are increasingly recognized as an important cause of febrile illness and mortality in sub-Saharan Africa. Human experimental
oral challenge studies with Salmonella can be used as a model to offer unique insights into host–pathogen interactions as well as a platform to efficiently test
new diagnostic and vaccine candidates. In this article, we review the background and use of human challenge studies to date
and discuss how findings from these studies may lead to progress in the control of invasive Salmonella disease in Africa.
Full-text · Article · Nov 2015 · Clinical Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Introduction
Respiratory syncytial virus (RSV) infection causes respiratory disease throughout life, with infants and the elderly at risk of severe disease and death. RSV001 is a phase 1 (first-in-man), open-label, dose-escalation, clinical trial of novel genetic viral-vectored vaccine candidates PanAd3-RSV and modified vaccinia virus Ankara (MVA)-RSV. The objective of RSV001 is to characterise the (primary objective) safety and (secondary objective) immunogenicity of these vaccines in healthy younger and older adults.
Methods and analysis
Heterologous and homologous ‘prime’/boost combinations of PanAd3-RSV and single-dose MVA-RSV are evaluated in healthy adults. 40 healthy adults aged 18–50 years test one of four combinations of intramuscular (IM) or intranasal (IN) PanAd3-RSV prime and IM PanAd3 or IM MVA-RSV boost vaccination, starting at a low dose for safety. The following year an additional 30 healthy adults aged 60–75 years test either a single dose of IM MVA-RSV, one of three combinations of IN or IM PanAd3-RSV prime and PanAd3-RSV or MVA-RSV boost vaccination used in younger volunteers, and a non-vaccinated control group. Study participants are self-selected volunteers who satisfy the eligibility criteria and are assigned to study groups by sequential allocation. Safety assessment includes the daily recording of solicited and unsolicited adverse events for 1 week after vaccination, as well as visit (nursing) observations and safety bloods obtained at all scheduled attendances. Laboratory measures of RSV-specific humoral and cellular immune responses after vaccination will address the secondary end points. All study procedures are performed at the Centre for Clinical Vaccinology and Tropical Medicine (CCVTM), Oxford, UK.
Ethics and dissemination
RSV001 has clinical trial authorisation from the Medicines and Healthcare Products Regulatory Agency (MHRA) and ethics approval from NRES Berkshire (reference 13/SC/0023). All study procedures adhere to International Conference on Harmonisation (ICH) Good Clinical Practice guidelines. The results of the trial are to be published in peer-reviewed journals, conferences and academic forums.
Trial registration number
[Show abstract][Hide abstract] ABSTRACT: High-throughput sequencing of the B cell receptor (BCR) repertoire can provide rapid characterization of the B cell response in a wide variety of applications in health, after vaccination and in infectious, inflammatory and immune-driven disease, and is starting to yield clinical applications. However, the interpretation of repertoire data is compromised by a lack of studies to assess the intra and inter-individual variation in the BCR repertoire over time in healthy individuals. We applied a standardized isotype-specific BCR repertoire deep sequencing protocol to a single highly sampled participant, and then evaluated the method in 10 further participants to comprehensively describe such variation. We assessed total repertoire metrics of mutation, diversity, VJ gene usage and isotype subclass usage, as well as tracking specific BCR sequence clusters. There was good assay reproducibility (both in PCR amplification and biological replicates), but we detected striking fluctuations in the repertoire over time that we hypothesize may be due to subclinical immune activation. Repertoire properties were unique for each individual, which could partly be explained by a decrease in IgG2 with age, and genetic differences at the immunoglobulin locus. There was a small repertoire of public clusters (0.5, 0.3 and 1.4% of total IgA, IgG and IgM clusters respectively), which was enriched for expanded clusters containing sequences with suspected specificity towards antigens that should have been historically encountered by all participants through prior immunization or infection. We thus provide baseline BCR repertoire information that can be used to inform future study design, and aid in interpretation of results from these studies. Furthermore our results indicate that BCR repertoire studies could be used to track changes in the public repertoire in and between populations that might relate to population immunity against infectious diseases, and identify the characteristics of inflammatory and immunological diseases.
Full-text · Article · Sep 2015 · Frontiers in Immunology
[Show abstract][Hide abstract] ABSTRACT: Purposeful infection of healthy volunteers with a microbial pathogen seems at odds with acceptable ethical standards, but
is an important contemporary research avenue used to study infectious diseases and their treatments. Generally termed ‘controlled
human infection studies’, this research is particularly useful for fast tracking the development of candidate vaccines and
may provide unique insight into disease pathogenesis otherwise unavailable. However, scarce bioethical literature is currently
available to assist researchers and research ethics committees in negotiating the distinct issues raised by research involving
purposefully infecting healthy volunteers. In this article, we present two separate challenge studies and highlight the ethical
issues of human challenge studies as seen through a well-constructed framework. Beyond the same stringent ethical standards
seen in other areas of medical research, we conclude that human challenge studies should also include: (i) independent expert
reviews, including systematic reviews; (ii) a publicly available rationale for the research; (iii) implementation of measures
to protect the public from spread of infection beyond the research setting; and (iv) a new system for compensation for harm.
We hope these additions may encourage safer and more ethical research practice and help to safeguard public confidence in
this vital research alternative in years to come.
No preview · Article · Sep 2015 · Public Health Ethics
[Show abstract][Hide abstract] ABSTRACT: Iron is a key pathogenic determinant of many infectious diseases. Hepcidin, the hormone responsible for governing systemic iron homeostasis, is widely hypothesized to represent a key component of nutritional immunity through regulating the accessibility of iron to invading microorganisms during infection. However, the deployment of hepcidin in human bacterial infections remains poorly characterized. Typhoid fever is a globally significant, human-restricted bacterial infection, but understanding of its pathogenesis, especially during the critical early phases, likewise is poorly understood. Here, we investigate alterations in hepcidin and iron/inflammatory indices following experimental human typhoid challenge.
[Show abstract][Hide abstract] ABSTRACT: 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.