Development of Newborn and Infant Vaccines

Children's Hospital Boston, Boston, MA 02115, USA.
Science translational medicine (Impact Factor: 15.84). 07/2011; 3(90):90ps27. DOI: 10.1126/scitranslmed.3001880
Source: PubMed

ABSTRACT Vaccines for early-life immunization are a crucial biomedical intervention to reduce global morbidity and mortality, yet their developmental path has been largely ad hoc, empiric, and inconsistent. Immune responses of human newborns and infants are distinct and cannot be predicted from those of human adults or animal models. Therefore, understanding and modeling age-specific human immune responses will be vital to the rational design and development of safe and effective vaccines for newborns and infants.

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Available from: Ofer Levy, Sep 29, 2015
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    • "DLS showed that the size of Gag:PCPP complexes was ~90 nm in diameter, a size range associated with successful uptake and antigen presentation by APCs, as also demonstrated in our study in both newborn and adult MoDCs. Neonatal immunization is hindered by distinct innate and adaptive responses including diminished antigen presentation, reduced IFN-g production, and sub-optimal antibody maturation and affinity [27]. In many developing countries birth is the first e and often the only e point of healthcare contact, motivating development of neonatal vaccines. "
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    ABSTRACT: Neonates and infants are susceptible to infection due to distinct immune responses in early life. Therefore, development of vaccine formulation and delivery systems capable of activating human newborn leukocytes is of global health importance. Poly[di(carboxylatophenoxy)phosphazene] (PCPP) belongs to a family of ionic synthetic polyphosphazene polyelectrolyte compounds that can form non-covalent interactions with protein antigens and demonstrate adjuvant activity in animals and in human clinical trials. However, little is known about their ability to activate human immune cells. In this study, we characterized the effects of PCPP alone or in combination with a model antigen (recombinant HIV-Gag (Gag)), on the maturation, activation and antigen presentation by human adult and newborn dendritic cells (DCs) in vitro. PCPP treatment induced DC activation as assessed by upregulation of co-stimulatory molecules and cytokine production. Studies benchmarking PCPP to Alum, the most commonly used vaccine adjuvant, demonstrated that both triggered cell death and release of danger signals in adult and newborn DCs. When complexed with Gag antigen, PCPP maintained its immunostimulatory characteristics while permitting internalization and presentation of Gag by DCs to HIV-Gag-specific CD4(+) T cell clones. The PCPP vaccine formulation outlined here has intrinsic adjuvant activity, can facilitate effective delivery of antigen to DCs, and may be advantageous for induction of beneficial T cell-mediated immunity. Moreover, polyphosphazenes can further reduce cost of vaccine production and distribution through their dose-sparing and antigen-stabilizing properties, thus potentially eliminating the need for cold chain distribution.
    Biomaterials 07/2014; 35(31). DOI:10.1016/j.biomaterials.2014.06.043 · 8.56 Impact Factor
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    • "In particular, neonatal deficiencies of innate cellular immune responses include a decreased production of interferons, IL-12p70, TNF and other proinflammatory/Th1-polarizing cytokines [3]. Divergent neonatal immune responses also pose a challenge to efforts to enhance early life immunization, which is a key global health strategy [4]. Lack of effective immunization strategies in the neonatal period (first 28 days of life) leads to a window of susceptibility to infections in newborns and infants lasting several months. "
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    ABSTRACT: Newborns display distinct immune responses that contribute to susceptibility to infection and reduced vaccine responses. Toll-like receptor (TLR) agonists may serve as vaccine adjuvants, when given individually or in combination, but responses of neonatal leukocytes to many TLR agonists are diminished. TLR8 agonists are more effective than other TLR agonists in activating human neonatal leukocytes in vitro, but little is known about whether different TLR8 agonists may distinctly activate neonatal leukocytes. We characterized the in vitro immuno-stimulatory activities of a novel benzazepine TLR8 agonist, VTX-294, in comparison to imidazoquinolines that activate TLR8 (R-848; (TLR7/8) CL075; (TLR8/7)), with respect to activation of human newborn and adult leukocytes. Effects of VTX-294 and R-848 in combination with monophosphoryl lipid A (MPLA; TLR4) were also assessed. TLR agonist specificity was assessed using TLR-transfected HEK293 cells expressing a NF-κB reporter gene. TLR agonist-induced cytokine production was measured in human newborn cord and adult peripheral blood using ELISA and multiplex assays. Newborn and adult monocytes were differentiated into monocyte-derived dendritic cells (MoDCs) and TLR agonist-induced activation assessed by cytokine production (ELISA) and co-stimulatory molecule expression (flow cytometry). VTX-294 was ∼100x more active on TLR8- than TLR7-transfected HEK cells (EC50, ∼50 nM vs. ∼5700 nM). VTX-294-induced TNF and IL-1β production were comparable in newborn cord and adult peripheral blood, while VTX-294 was ∼ 1 log more potent in inducing TNF and IL-1β production than MPLA, R848 or CL075. Combination of VTX-294 and MPLA induced greater blood TNF and IL-1β responses than combination of R-848 and MPLA. VTX-294 also potently induced expression of cytokines and co-stimulatory molecules HLA-DR and CD86 in human newborn MoDCs. VTX-294 is a novel ultra-potent TLR8 agonist that activates newborn and adult leukocytes and is a candidate vaccine adjuvant in both early life and adulthood.
    PLoS ONE 03/2013; 8(3):e58164. DOI:10.1371/journal.pone.0058164 · 3.23 Impact Factor
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    • "It is estimated that 87% of children below the age of five are infected with malaria in the Osun State in south-western Nigeria [34], and validating these methodologies is important for future studies in this area. For example, birth to age five is an important range for the administration and study of many prophylactic paediatric vaccines and World Health Organization recommendations for routine immunization within this age group in Nigeria include both measles and yellow fever vaccines [35]. "
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    ABSTRACT: Background Malaria is a major cause of morbidity and mortality worldwide with over one million deaths annually, particularly in children under five years. This study was the first to examine plasma cytokines, chemokines and cellular immune responses in pre-school Nigerian children infected with Plasmodium falciparum from four semi-urban villages near Ile-Ife, Osun State, Nigeria. Methods Blood was obtained from 231 children (aged 39–73 months) who were classified according to mean P. falciparum density per μl of blood (uninfected (n = 89), low density (<1,000, n = 51), medium density (1,000-10,000, n = 65) and high density (>10,000, n = 22)). IL-12p70, IL-10, Nitric oxide, IFN-γ, TNF, IL-17, IL-4 and TGF-β, C-C chemokine RANTES, MMP-8 and TIMP-1 were measured in plasma. Peripheral blood mononuclear cells were obtained and examined markers of innate immune cells (CD14, CD36, CD56, CD54, CD11c AND HLA-DR). T-cell sub-populations (CD4, CD3 and γδTCR) were intracellularly stained for IL-10, IFN-γ and TNF following polyclonal stimulation or stimulated with malaria parasites. Ascaris lumbricoides was endemic in these villages and all data were analysed taking into account the potential impact of bystander helminth infection. All data were analysed using SPSS 15 for windows and in all tests, p <0.05 was deemed significant. Results The level of P. falciparum parasitaemia was positively associated with plasma IL-10 and negatively associated with IL-12p70. The percentage of monocytes was significantly decreased in malaria-infected individuals while malaria parasitaemia was positively associated with increasing percentages of CD54+, CD11c+ and CD56+ cell populations. No association was observed in cytokine expression in mitogen-activated T-cell populations between groups and no malaria specific immune responses were detected. Although A. lumbricoides is endemic in these villages, an analysis of the data showed no impact of this helminth infection on P. falciparum parasitaemia or on immune responses associated with P. falciparum infection. Conclusions These findings indicate that Nigerian children infected with P. falciparum exhibit immune responses associated with active malaria infection and these responses were positively associated with increased P. falciparum parasitaemia.
    Malaria Journal 01/2013; 12(1):5. DOI:10.1186/1475-2875-12-5 · 3.11 Impact Factor
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