Influenza Neuraminidase Virus-Like Particle-Based Nanocarriers as a New Platform for the Delivery of Small-Peptide Antigens.

A new and simple platform to produce a nanocarrier for small-peptide antigen delivery was developed. Virus-like particles (VLPs) were of interest due to their good cell-penetrating properties and ability to protect target molecules from degradation. In this study, the VLP that was entirely formed by influenza neuraminidase (NA), NA-VLPs, was employed. The platform construction includes the genetic engineering of target peptides into the NA structure immediately above its stalk, at the bottom of the NA head, by an overlap extension PCR. The resulting chimeric gene is next expressed in stably transformed insect cells. The recombinant NA protein produced by the insect cells is then naturally assembled into the NA-VLPs that display those peptides on their surfaces. For the platform demonstration, Angiotensin II (AngII) octapeptide hormones that raise blood pressure were chosen as a model peptide antigen. The NA-VLPs displaying AngII peptides were successfully produced by the stably transformed insect cells. The AngII octapeptides were successfully delivered by the NA-AngII VLPs as the anti-AngII antibodies were raised in hypertensive rats. The antibodies effectively neutralized the AngII peptide hormone in these rats, as demonstrated by the decrease in systolic blood pressure of the immunized rats. Thus, NA-VLP nanocarriers represent a promising platform for delivering small-peptide antigens to stimulate antibody production.