Safety and immunogenicity of the epicutaneous reactivation of pertussis toxin immunity in healthy adults: a phase I, randomized, double-blind, placebo-controlled trial.

OBJECTIVES: Protection induced by acellular vaccines can be short, requiring novel immunization strategies. Objectives of this study were to evaluate safety and capacity of a recombinant pertussis toxin (PTgen) -coated Viaskin® epicutaneous patch to recall memory responses in healthy adults. METHODS: This double-blind, placebo-controlled randomized trial (Phase I) assessed the safety and immunogenicity of PTgen administered on days 0 and 14 to healthy adults using Viaskin® patches applied directly or after epidermal laser-based skin preparation. Patch administration was followed by Boostrix®dTpa on day 42. Antibodies were assessed at days 0, 14, 28, 42 and 70. RESULTS: Among 102 volunteers enrolled, 80 received Viaskin-PT (Viaskin-PT 25 µg (n = 25), Viaskin-PT 50 µg (n = 25), laser + Viaskin-PT 25 µg (n = 5), laser + Viaskin-PT 50 µg (n = 25)), Viaskin-placebo (n = 10) or laser + Viaskin-placebo (n = 2). Incidence of adverse events was similar across groups (any local event: 21/25 (84.0%), 24/25 (96.0%), 4/5 (80.0%), 24/25 (96.0%), 8/10 (80.0%), 10/12 (83.0%), respectively). Direct application induced no detectable response. On day 42, PT-IgG geometric mean concentrations were significantly higher following laser + Viaskin-PT 25 µg and 50 µg (139.87 (95% CI 87.30-224.10) and 121.76 (95% CI 95.04-156.00), respectively), than laser + Viaskin-placebo (59.49, 95% CI 39.37-89.90). Seroresponse rates were higher following laser + Viaskin-PT 25 µg (4/5 (80.0%), 95% CI 28.4-99.5) and 50 µg (22/25 (88.0%), 95% CI 68.8-97.5) than laser + Viaskin-placebo (0/12 (0.0%), 95% CI 0.0-26.5). CONCLUSIONS: Viaskin-PT applied after laser-based epidermal skin preparation showed encouraging safety and immunogenicity results: anti-PT booster responses were not inferior to those elicited by Boostrix®dTpa. This study is registered at ClinicalTrials.gov (NCT03035370) and was funded by DBV Technologies.

Impact of bispectral index for monitoring propofol remifentanil anaesthesia. A randomised clinical trial.

BACKGROUND: Previous research has shown that the use of the bispectral index (BIS) monitor to measure the depth of anaesthesia reduces the amount of anaesthetics administered and the recovery time from general anaesthesia. The effect of BIS on recovery from anaesthesia and consumption of anaesthetics in a paediatric population receiving total intravenous anaesthesia (TIVA) with propofol and remifentanil has not been studied. METHODS: A single-blind, single-centre clinical trial. One hundred fifty-seven patients were enrolled. They were scheduled for ear, nose, and throat surgery and stratified according to age groups (1-3 years, 4-11 years, 12-17 years, 18-65 years) and type of operation, yielding a total of nine subgroups. Patients were randomly allocated to receive either a TIVA with propofol and remifentanil according to conventional clinical practice (control) or guided by BIS. Normalised propofol (µg/kg/min) and remifentanil (µg/kg/min) consumption and time to extubation (s) were the outcome measures. RESULTS: Children aged 1-3 years in the BIS group had a longer time to extubation compared with controls (P: 0.04). Patients aged 12-17 years in the BIS group received higher maintenance infusion rates of propofol compared with controls (P = 0.02). No significant difference for the outcome variables was evidenced in the other age groups. CONCLUSION: BIS monitoring for guidance of propofol-remifentanil anaesthesia does not result in reduced consumption of anaesthetics and does not reduce time to extubation in adult and children compared with conventional practice.

The second Geneva Consensus: Recommendations for novel live TB vaccines.

Infection with Mycobacterium tuberculosis continues to be a major public health burden in most developing parts of the world and efforts to develop effective strategies for containing the disease remain a priority. It has long been evident that effective mass vaccination programmes are a cost effective and efficient approach to controlling communicable diseases in a public health setting and tuberculosis (TB) continues to be a major target. One approach with increasing acceptance is based upon on live mycobacterial vaccines, either as recombinant BCG or rationally attenuated M. tuberculosis, thus generating a new live TB vaccine. The Geneva Consensus published in March 2005 set out the opinion on priorities and requirements for developing live mycobacterial vaccines for Phase I trials. In the intervening period much progress has been made in both preclinical and clinical development of new TB vaccines and has provided the impetus for organising the second Geneva Consensus (held at WHO headquarters, April 2009) to discuss issues, including: i. Explore the regulatory requirements for live TB vaccines to enter Phase I trials, in particular those based on attenuated M. tuberculosis. Particular attention was paid to the characterisation and safety package likely to be required, including issues of attenuation, the presence of antibiotic resistance markers in live vaccines and the nature of any attenuated vaccine phenotype. ii. To identify the general criteria for further clinical development from Phase I through to Phase III. iii. Obtain a perspective of the regulatory landscape of developing countries where Phase II and III trials are to be held. iv. Review manufacturing considerations for live TB vaccines and relevance of the WHO and European Pharmacopeia guidelines and requirements for BCG vaccine. v. Consider requirements and associated issues related to the use of these new vaccines within an existing BCG vaccination programme.

[Vaccination and autoimmunity: a real or imagined risk?]. / Vaccination et auto-immunité: risque réel ou imaginaire?

A better understanding of mechanisms leading to or limiting the development of autoimmune diseases allows an evaluation of the real risk associated with infections or immunizations. It appears that regulatory mechanisms efficiently limit autoimmune responses following exposure to mimicking antigens or to activators of innate autoimmunity. When strict criteria of causality are applied, autoimmune adverse effects of vaccination are scarce. In fact, recent allegations suggesting such associations have not been confirmed. The use of vaccines against hepatitis B, influenza, and pneumococcal infections in patients with an ongoing autoimmune disease is actually recommended in view of the favourable risk-benefit equation.

Quality assessment of combinatorial pooled libraries using mass spectrometry.

Parallel synthesis techniques aim to prepare collections of single compounds which, once tested, can easily be identified by their sole location in the synthesic array. On the other hand, true combinatorial chemistry produces libraries of compounds as mixtures of variable size which require a deconvolution procedure for identification of the active hits or leads. In the latter case, analytical methods are crucial for the success of the strategy and mass spectrometry plays a major role. If the goal is to identify all the library components, including expected products as well as by-products, various mass spectrometric techniques may be necessary. Library components can be separated according to their mass by increasing mass resolution or by their elution time by coupling liquid chromatography and mass spectrometry. The efficiency of such separation techniques are discussed as a function of the size and the degeneracy of the library. Library members possess common structural features which impart similar fragmentation patterns after ionization in the gas phase. This feature can be exploited by tandem mass spectrometry to specifically detect subfamilies of products. Examples of precursor ion scans, product ion scans and constant neutral loss scans will be shown that facilitate partial characterization of libraries. To solve the difficult problem of the quantitative analysis of libraries, i.e., to evaluate their equimolarity, the use of an evaporative light scattering detector (ELSD) or a chemiluminescent nitrogen detector (CLND) is suggested as more appropriate.

Induction of adult-like antibody, Th1, and CTL responses to measles hemagglutinin by early life murine immunization with an attenuated vaccinia-derived NYVAC(K1L) viral vector.

Although initially developed in adult animals, novel viral vectors expressing recombinant measles antigens must eventually prove their success in the early life setting, where the efficacy of the currently used live-attenuated measles virus vaccine is limited. The immunological requirements for vaccine candidates include the generation of protective antibody responses as well as the induction of Th1 and cytotoxic T lymphocytes (CTL) responses, which is challenging in the neonatal setting. Here, we report that young BALB/c mice immunized with a single dose of a vaccinia-based NYVAC(K1L) vector generate adult-like antihemagglutinin (HA) antibody responses as well as adult-like Th1 and CTL responses. Despite this strong immunogenicity in early life, antibody responses (but not T-cell responses) to a single dose of NYVAC(K1L)-HA remained susceptible to inhibition by preexisting measles antibodies, calling for use of prime-boost strategies. NYVAC(K1L)-HA is the first attenuated live viral vector demonstrated as capable of inducing adult-like antibody, Th1, and CTL responses against measles in an early life murine immunization model, a capacity previously only reported for measles DNA vaccines.

Delayed and deficient establishment of the long-term bone marrow plasma cell pool during early life.

Early life antibody responses are characterized by a rapid decline, such that antigen-specific IgG antibodies decline to baseline levels within months following infant immunization. This generic observation remains unexplained. Here, we have analyzed the induction and organ-localization of antigen-specific IgG antibody-secreting cells (ASC) following immunization of 1-week-old or adult BALB/c mice with tetanus toxoid (TT), a T-dependent antigen. Early life priming induced only slightly lower numbers of TT-specific IgG ASC in the spleen, and these reached adult levels following repeat immunization. In contrast, early life immunization generated much fewer bone marrow plasma cells than in adults, even after boosting. A similar limitation of the natural development of the bone marrow pool of ASC was observed. Transfer experiments with adult or early life spleen ASC indicated limited homing of TT-specific adult ASC to the bone marrow of 4-week-old mice as compared to adult recipients, whereas homing patterns were similar when early life or adult ASC were transferred into adult recipients. These observations suggest that a limited bone marrow B cell homing capacity and, as a result, relatively deficient bone marrow ASC responses, are critical factors which may explain the limited persistence of IgG antibodies to T-dependent antigens in early life.

Adjuvant effects of CpG oligodeoxynucleotides on responses against T-independent type 2 antigens.

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) are potent in vitro B-cell activators and they have been successfully used to increase in vivo antibody responses to T-dependent peptide and protein antigens. In contrast, the use of CpG-ODN to enhance in vivo antibody responses to various T-independent type 2 (TI-2) antigens has recently generated contradictory results. In this study, we compared the CpG-ODN stimulatory effect on antibody responses of adult and young BALB/c mice to trinitrophenylaminoethyl-carboxymethyl (TNP) -Ficoll and to polysaccharides (PS) from several distinct serotypes of Streptococcus pneumoniae (SPn). CpG-ODN co-administration significantly enhanced antigen-specific immunoglobulin M (IgM), IgG, IgG1 and IgG2a titres to TNP-Ficoll. The depletion of CD4+ cells by monoclonal antibodies (GK1.5) identified their essential role in CpG-ODN-mediated enhancement of antibody responses. In contrast to TNP-Ficoll, CpG-ODN failed to enhance IgM and IgG responses to any of the 18 SPnPS serotypes tested. Providing T-cell epitopes by the conjugation of SPnPS to the carrier protein tetanus toxoid again allowed CpG-ODN to mediate enhancement of IgG, IgG2a and IgG3 responses to most SPnPS serotypes. Thus, antigen-presenting cell/T-cell interaction appears to largely mediate the in vivo influence of CpG-ODN on antibody responses to TI-2 antigens. In early life, additional factors limit CpG-ODN modulation of antibody responses to TI-2 antigens.

Limitations of in vivo IL-12 supplementation strategies to induce Th1 early life responses to model viral and bacterial vaccine antigens.

The limited induction of Th1 and cytotoxic immune responses is regarded as the main reason for the increased susceptibility to intracellular microorganisms in early life. Recently, in vitro IL-12 supplementation was shown to enhance the limited IFN-gamma release of measles-specific infant T cells. Using a series of IL-12 delivery systems, we show here that in vivo IL-12 supplementation may enhance early life murine Th1 responses to two model vaccine antigens, measles virus hemagglutinin and tetanus toxin peptide. However, this required multiple repeat injections of recombinant rIL-12, which were poorly tolerated in young mice. Local IL-12 delivery by an IL-12 expressing canarypox vector proved safe but failed to modulate vaccine responses. An IL-12 DNA plasmid or a CD40L DNA plasmid efficiently enhanced neonatal Th1 responses to measles hemagglutinin DNA vaccine. However, both plasmids only enhanced Th1 responses to DNA and not to peptide, protein, or live viral vaccines. Thus, inducing adult-like Th1 responses may be achieved in vivo by inducing (CD40L) or substituting for (IL-12 supplementation) optimal activation of neonatal APC. However, these immunomodulatory effects appear limited to certain antigen-presentation approaches and may not be broadly applicable to vaccines.

Combining DNA and protein vaccines for early life immunization against respiratory syncytial virus in mice.

Early life responses to respiratory syncytial virus (RSV)-F DNA and RSV-F protein immunization were studied in murine models of neonatal immunization. RSV-F DNA induced similar antibody (Ab) responses, antigen-specific IFN-gamma production and cytotoxic T lymphocyte (CTL) responses in 1-week-old and adult BALB / c mice. In contrast, RSV-F protein induced much higher IL-5 responses in early life. Both vaccines elicited Ab and CTL responses in spite of maternal Ab, but with distinctive kinetics. Sequential RSV-F DNA priming / protein boosting primed 1-week-old mice for RSV-F-specific CTL responses, reduced IL-5 production and enhanced Ab responses. In contrast, IL-5 exceeded IFN-gamma responses when young mice were primed with protein and boosted with DNA. Last, when protein and DNA immunization were combined, a single vaccine dose induced early Ab responses, preferential IL-5 responses but strong CTL responses. Sequential or combined DNA / protein immunization thus represent interesting strategies for early life immunization.

Physico-chemical and biological analysis of true combinatorial libraries.

Combinatorial libraries offer new sources of compounds for the research of pharmacological agents such as receptor ligands, enzyme inhibitors or substrates and antibody-binding epitopes. The present review stresses the main roles played by both physico-chemical analysis, particularly when complex mixture of compounds are synthesized as libraries, and biological analysis from which active compounds are identified. After a brief discussion of semantic problems related to the designation of the product mixtures, the physico-chemical analysis of mixtures is reviewed with special emphasis on mass spectrometric techniques. These methods are able both to give a representative view of a library composition and to identify single critical compounds in large libraries. Then the biological screening of such combinatorial libraries is critically discussed with respect to the power and limitations of the methods used for the identification of the active components. Special attention is given to the complex process of library deconvolution. It is pointed out that while combinatorial techniques have evolved towards sophisticated high-tech methods, simple and robust biochemical tests should be used to deconvolute. From a large panel of published examples, a set of trends are identified which should help investigators to choose the most appropriate assay for the discovery of new entities.

Protective efficacy against respiratory syncytial virus following murine neonatal immunization with BBG2Na vaccine: influence of adjuvants and maternal antibodies.

Alum-adsorbed BBG2Na, a recombinant vaccine derived in part from the respiratory syncytial virus (RSV) subgroup A G protein, induced moderate antibody titers after 1 immunization in 1-week-old mice but conferred complete lung protection upon RSV challenge. The anti-BBG2Na IgG1-IgG2a neonatal isotype profile was suggestive of dominant Th2 responses compared with those in adults. Formulation of BBG2Na with a Th1-driving adjuvant efficiently shifted neonatal responses toward a more balanced and adultlike IgG1-IgG2a profile without compromising its protective efficacy. BBG2Na-induced protective immunity was maintained even after early life immunization in the presence of high titers of maternal antibodies. Under these conditions, the protective efficacy (86%-100%) reflected the high capacity of the nonglycosylated G2Na immunogen to escape inhibition by RSV-A-induced maternal antibodies. Thus, immunization with BBG2Na protected against viral challenge despite neonatal immunologic immaturity and the presence of maternal antibodies, two major obstacles to neonatal RSV vaccine development.

CpG oligodeoxynucleotides can circumvent the Th2 polarization of neonatal responses to vaccines but may fail to fully redirect Th2 responses established by neonatal priming.

Neonatal murine responses to a panel of conventional vaccines differ qualitatively from adult responses by a particular polarization toward a Th2 pattern and a frequent limitation of the Th1 and CTL responses required for protection against intracellular microorganisms. In contrast, DNA vaccines induce adult-like Th1/CTL neonatal responses against the same vaccine Ags. In this report, we show that this can be related to their content in unmethylated CpG motifs. Oligodeoxynucleotides (ODN) containing CpG motifs activate neonatal APCs to produce IL-12 in vitro and induce adult-like Th1 responses to tetanus toxoid and measles Ags in vivo, with production of IgG2a-specific Abs and adult-like secretion of IFN-gamma and IL-5 by Ag-specific T cells. However, in spite of their capacity to trigger neonatal B cell proliferation in vitro, CpG-ODN only partially enhanced early life Ab responses. Finally, using Th1-driving CpG-ODN with the boosting dose of a protein vaccine was sufficient to redirect adult but not neonatally primed Th2 responses. These observations could be important for the development of novel vaccines that will have to be effective early in life.

Influence of maternal antibodies on vaccine responses: inhibition of antibody but not T cell responses allows successful early prime-boost strategies in mice.

The transfer of maternal antibodies to the offspring and their inhibitory effects on active infant immunization is an important factor hampering the use of certain vaccines, such as measles or respiratory syncytial virus vaccine, in early infancy. The resulting delay in protection by conventional or novel vaccines may have significant public health consequences. To define immunization approaches which may circumvent this phenomenon, experiments were set up to further elucidate its immunological bases. The influence of maternal antibodies on antibody and T cell responses to measles hemagglutinin (MV-HA) were analyzed following MV-HA immunization of pups born to immune or control BALB/c mothers using four different antigen delivery systems: live or inactivated conventional measles vaccine, a live recombinant canarypox vector and a DNA vaccine. High levels (> 5 log10) of maternal anti-HA antibodies totally inhibited antibody responses to each of the vaccine constructs, whereas normal antibody responses were elicited in presence of lower titers of maternal antibodies. However, even high titers of maternal antibodies affected neither the induction of vaccine-specific Th1/Th2 responses, as assessed by proliferation and levels of IFN-gamma and IL-5 production, nor CTL responses in infant mice. On the basis of these unaltered T cell responses, very early priming and boosting (at 1 and 3 weeks of age, respectively) with live measles vaccine allowed to circumvent maternal antibody inhibition of antibody responses in pups of immune mothers. This was confirmed in another immunization model (tetanus toxoid). It suggests that effective vaccine responses may be obtained earlier in presence of maternal antibodies through the use of appropriate immunization strategies using conventional or novel vaccines for early priming.

Maternal immunity and infant responses to immunization: factors influencing infant responses.

The presence of maternally-derived antibodies at the time of immunization is known to interfere frequently with active immunization, with variable levels of clinical significance. Deciphering the rules as the basis of such inhibitory effects on infant vaccine responses would certainly contribute to the development of vaccination strategies for early life. These questions were addressed in murine neonatal or early life immunization models using various antigens (measles, tetanus, RSV) and antigen-presentation systems (peptides, proteins, live attenuated vaccines, live recombinant vectors or DNA plasmids) in the absence or presence of maternal antibodies. Factors identified as crucial determinants of maternal antibody-mediated effects on both live and non-live vaccines include the relative amount of maternal antibodies and of vaccine antigens present at immunization, antigenic conformation, epitope specificity and the distinct influence on B-cell and T-cell vaccine responses.

Registro de ensayos con vacunas del Programa Mundial de Vacunas e Inmunización de la OMS / The WHO Global Programme for Vaccines and Immunization Vaccine Trial Registry

En 1995, el Programa Mundial de Vacunas e Immunización de la OMS estableció un registro para ensayos con vacunas. En septiembre de 1996, este registro contenía 50 ensayos de vacunación patrocinados por la OMS, de los cuales 25 (50 por cien) eran estudios ya terminados. Las vacunas que se habían estudiado con mayor frecuencia fueron las de sarampión (9 ensayos), poliovirus (8 ensayos), cólera (8 ensayos), Escherichia coli enterotoxígena (4 ensayos) y neumococo (4 ensayos). Casi 80 por cien de estos ensayos se llevaron a cabo en países en desarrollo, principalmente en el Africa. En los 25 ensayos ya terminados, los resultados investigados fueron la respuesta inmunitaria (24 ensayos), las reacciones adversas (13 ensayos), la morbilidad (4 ensayos) y la mortalidad (1 ensayo). La OMS contribuyó a estos ensayos con el aporte indirecto de fondos, ayuda con el diseño metodológico, visitas a las localidades, el análisis de los datos, la adquisición de vacunas y la investigación de su potencia

Registro de ensayos con vacunas del Programa Mundial de Vacunas e Inmunización de la OMS / The WHO Global Programme for Vaccines and Immunization Vaccine Trial Registry

En 1995, el Programa Mundial de Vacunas e Immunización de la OMS estableció un registro para ensayos con vacunas. En septiembre de 1996, este registro contenía 50 ensayos de vacunación patrocinados por la OMS, de los cuales 25 (50 por cien) eran estudios ya terminados. Las vacunas que se habían estudiado con mayor frecuencia fueron las de sarampión (9 ensayos), poliovirus (8 ensayos), cólera (8 ensayos), Escherichia coli enterotoxígena (4 ensayos) y neumococo (4 ensayos). Casi 80 por cien de estos ensayos se llevaron a cabo en países en desarrollo, principalmente en el Africa. En los 25 ensayos ya terminados, los resultados investigados fueron la respuesta inmunitaria (24 ensayos), las reacciones adversas (13 ensayos), la morbilidad (4 ensayos) y la mortalidad (1 ensayo). La OMS contribuyó a estos ensayos con el aporte indirecto de fondos, ayuda con el diseño metodológico, visitas a las localidades, el análisis de los datos, la adquisición de vacunas y la investigación de su potencia