Screening vaccine formulations for biological activity using fresh human whole blood

Abstract

Understanding the relevant biological activity of any pharmaceutical formulation destined for human use is crucial. For vaccine-based formulations, activity must reflect the expected immune response, while for non-vaccine therapeutic agents, such as monoclonal antibodies, a lack of immune response to the formulation is desired. During early formulation development, various biochemical and biophysical characteristics can be monitored in a high-throughput screening (HTS) format. However, it remains impractical and arguably unethical to screen samples in this way for immunological functionality in animal models. Furthermore, data for immunological functionality lag formulation design by months, making it cumbersome to relate back to formulations in real-time. It is also likely that animal testing may not accurately reflect the response in humans. For a more effective formulation screen, a human whole blood (hWB) approach can be used to assess immunological functionality. The functional activity relates directly to the human immune response to a complete formulation (adjuvant/antigen) and includes adjuvant response, antigen response, adjuvant-modulated antigen response, stability, and potentially safety. The following commentary discusses the hWB approach as a valuable new tool to de-risk manufacture, formulation design, and clinical progression.

A high ratio of IC31®adjuvant to antigen is necessary for H4 TB vaccine immunomodulation

“…While a reproducible proinflammatory TNFa cytokine response is induced within 24 hours of in vitro stimulation with TLR4-Adjuvant stimulation, 14,17 no such response was observed with IC31 (data not shown), confirming results from a previous report. 6 The data demonstrates a distinct in vitro functional difference between TLR4-Adjuvant and IC31 activity.…”

“…However, it is well known that immunogenic and evolutionary differences exist between mice and humans, and expression and usage of TLR9 is species-specific. [14][15][16] Although animal models provide a valid representation of the complex in vivo environment, data from these studies require translation to humans to ensure more realistic and specific functional evaluations.…”

Phosphate substitution in an AlOOH - TLR4 adjuvant system (SPA08) modulates the immunogenicity of Serovar E MOMP from Chlamydia trachomatis

“…This is supported by the fact that TLR agonists have been shown to enhance their pro-inflammatory adjuvant effects when bound to the aluminum salt. 28,29 Although E6020 remained adsorbed, the significant decrease in the strength of adsorption observed upon phosphate substitution may be responsible for the change in the cytokine profile. Upon vaccine injection, it is likely that E6020 in formulations with high phosphate substitution and thus a reduced strength of adsorption may become desorbed from the AlOOH due to the relatively high concentration of competing ions in the interstitial fluid.…”

Natural Vaccine Adjuvants and Immunopotentiators Derived From Plants, Fungi, Marine Organisms, and Insects

“…100 Whole fresh blood with antigen plus adjuvant can be followed by monitoring of TNF-a, IL-6, and IL-1b or IFN-g release by enzyme-linked immunosorbent assay (ELISA). 101 Assays used in the development of vaccines and associated adjuvants include stimulation of lymphocyte proliferation and cytokine productiondeither Th1 (IL-2, IFN-g, and TNF-a) or Th2 (IL-4, IL-5, and IL-10); quantitation of the expression of cell activation markers on cell surface such as CD25, CD69, CD80, and CD86 by using a fluorescenceactivated cell sorter (FACS) 102 ; quantitation of different lymphocyte subpopulations by FACS, e.g., CD3, CD4, CD8, CD16/CD56, CD19, CD20, and CD45; augmentation of NK cell cytotoxicity; stimulation of IL-1, IL-6, and TNF-a production by macrophages in response to LPS; and stimulation of antibody plaqueeforming cells and antibody production. In vivoeassociated assays include stimulation of antibody titers by specific antigens and determination of Th1/Th2 cytokine profiles.…”