VLP's structure is similar to virus structure, but it lacks genetic material and not infects host cells. These self-assembling nanomaterials are generated from various organisms. VLPs offer a utility platform to deliver bio- and nanomaterials for vaccines by using the internal cavity within their structures. The self-assembly of viral structural proteins gives rise to icosahedral or rod-shaped VLPs. These VLPs efficiently enter antigen-presenting cells (APCs), which leads to the cross-presentation of antigens associated with both major histocompatibility complex (MHC) class I and class II. This results in the elicitation of cellular and humoral immune responses. In addition, VLPs exhibit antigens in a structured pattern on their surface that induces T cell-independent and T cell-dependent B cell reactions. By utilizing VLPs, the transportation of heterologous antigenic structures and DNA molecules to antigen-presenting cells (APCs) is facilitated.
Fig.1 Examples of VLPs. (Nooraei, et al., 2021)
CD BioGlyco offers Qβ VLPs as highly efficient carriers for vaccine development. Qβ VLPs are produced in large quantities through recombinant expression in Escherichia coli, complying with good manufacturing practices. It is crucial to select the appropriate purification scheme. It helps maintain the integrity of the constructed and synthesized VLPs for their intended downstream applications. We purify VLP commonly following the principles that are shown in the following figure.
Fig.2 The principles of VLP purification. (CD BioGlyco)
We utilize VLPs to synthesize vaccines targeting Streptococcus pneumoniae Polysaccharides. Our approach involves using S. pneumoniae serotypes 3 (TS3) and 14 (TS14) to conjugate, as they possess diverse tetrasaccharide repeating units. TS3 consists of a linear disaccharide repeat (Glcβ1-3GlcAβ1-4Glcβ1-3GlcAβ1), while TS14 features a branched tetrasaccharide (Galβ1-4Glcβ1-6[Galβ1-4]GlcNAcβ1). It has been shown that both of these structures elicit antibodies specific to the bacterial capsule of their respective serotypes.
To conjugate glycan, we introduce a terminal azidoethanol linker into the tetrasaccharides. Through copper-catalyzed azide-alkyne cycloaddition (CuAAC), bioorthogonal azide groups are effectively recognized. The glycans are then attached to bacteriophage Qβ VLPs, which act as an optimal platform for display. The glycan conjugation process involves two steps. First, alkyne groups are attached to amines on the VLP surface. Subsequently, CuAAC conjugation is performed to link the glycan to the VLP. We characterize those VLP conjugates by using size-exclusion chromatography to confirm integrity post-modification. Besides, we utilize microfluidic gel electrophoresis to assess quality and utilize MALDI mass spectrometry to determine glycan attachment density.
Fig.3 Synthesis of Qβ-oligosaccharide conjugates. (CD BioGlyco)
CD BioGlyco is a leading company in Carbohydrate-based Vaccine Development. With our state-of-the-art Glyco™ Vaccine Development Platform, we are constantly innovating in the field of glycobiology. Our team has many renowned experts that excel in developing cutting-edge vaccines. CD BioGlyco is confident about our unrivaled expertise and commits to advancing carbohydrate-based vaccine research. Don't hesitate to contact us if you are interested in our services, we would be happy to provide you with more detailed information.
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