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Department of Pediatrics

Formulation

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Vaccine Formulation and Delivery Systems Unit

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The unit handles all the formulations of Texas Children's Hospital Center for Vaccine Development, turning recombinant antigens into safe, long-term stable and potent vaccines. The main activities of the unit include:

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Buffer Screening

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Protein stability is greatly dependent on the buffer in which the proteins are dissolved. Therefore, the Formulation Development Unit screens many different buffers and excipients to select the most suitable conditions to ensure optimal protein stability. The screening strategy involves several advanced analytical techniques, such as Size Exclusion (SEC) HPLC, Differential Scanning Fluorimetry, Dynamic Light Scattering, Turbidity Screening, FTIR and Circular Dichroism to help selecting the most optimal buffer conditions. Only buffers and excipients that are generally accepted as safe and approved by the FDA are considered for final formulation. After the buffers and excipients are selected, the stabilized protein solutions are extensively monitored for possible chemical or physical degradation in accelerated stability experiments and long term stability experiments.

This work is done in close collaboration with the Process Development Unit and the Molecular Discovery Unit within the vaccine center. Collaborators from other organizations include the Macromolecular and Vaccine Stabilization Center (MVSC) at Kansas University.

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Adjuvant Selection

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To make potent vaccines from recombinant antigens, the formulation generally requires one or more adjuvants to help generate adequate immune responses. The Formulation Unit collaborates with the Preclinical Testing Unit to study and select the most suitable adjuvants for each specific project. The most common adjuvants currently used are aluminum salts, but the research team also looks into emerging immunostimulatory molecules such as GLA, E6020, CpG and Imiquimod.

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Delivery Systems

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To improve the delivery of antigens and adjuvants to antigen-presenting cells, we are exploring new delivery systems. Part of our research is based on oil-in water emulsions, another delivery strategy is focused on PLGA microparticles. These delivery systems can be exploited to control the Th1/Th2 polarization of the immune response. The unit evaluates the immunogenicity of the advanced vaccine formulations in mice in collaboration with the Preclinical Testing Unit . The recall response of splenocytes to re-stimulation with protein antigen is measured by CD4 and CD8 T cell proliferation and secretion of cytokines by T cells.

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Laboratory Facilities

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The Vaccine Formulation and Delivery Systems Unit has a formulation room, plus shared space in Texas Children's Hospital Center for Vaccine Development, including a chemical alcove and a tissue culture room.

The major equipment includes the Alliance and Waters HPLC system, a Wyatt HPLC Light Scattering Detector, a Spectra M3 Plate Reader, a Bio-Rad GS 800 Densitometer, Jasco Circular Dichroism, Bruker FTIR spectroscope, Charles River Endosafe PTS system and a UPLC Waters Acquity, Malvern Zetasizer ZS90, Labconco Triad freeze dryer, Buchi Rotary Evaporator, PowerGen homogenizer, digital probe sonifier, BioTek plate washer, EVOS digital inverted fluorescence microscope.

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Unit Director

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Jeroen Pollet, Ph.D.

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Proteins: Size Exclusion Chromatography

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Wanderson Rezende gives an impromptu lecture on proteins.