Although it is not well defined exactly which proteins are bound to the VLP, it is likely that the efficiency of this coupling and size constraints limit conjugation of lysate proteins, such that lysate delivered on VLP equates quantitatively to less tumour antigenic protein than pulsing DC with unconjugated lysate by at least half.
Serological assays based on virus-like particles (VLPs) make it possible to detect HPV antibodies likely indicative of previous exposure to HPV infection.
A recombinant bacteria-derived protein has the advantage over mammalian cell-culture derived VLPs as it can be produced rapidly, inexpensively, and in higher yield, and likely can be quantified more precisely for diagnostic applications.
Although virus-derived transient expression systems have been extensively used for the production of pharmaceutical proteins, including VLPs, in plants, it is only recently that this technology has been used to express active enzymes, with a view to manipulate plant metabolism.
In a previous study, a recombinant genotype 1 HEV peptide (HEV 239; Hecolin; Xiamen Innovax Biotech, Xiamen, China) was found to occur in solution as large aggregates rather than true VLPs [ 32], but it was highly immunogenic.
Using chemical cross-linkers, any antigen can be placed directionally onto the VLP surface, rendering it highly immunogenic.
However, the main concern for using HBc VLPs as vaccines is that it is insufficient enough to induce immune responses by using HBc antigens alone.
To analyze the protein constituents of purified VLPs, the samples quantified by Quant-iT Protein Assay Kit (Invitrogen) were mixed with Lämmle SDS-PAGE sample buffer, boiled for 5 min, and separated in a 7.5 17.5% gradient gel.
This assay provides only a comparative assessment of VLP formation since it only accounts for VLPs that are able to incorporate and passage minigenomes.
