VaxiPatch™, a novel vaccination system comprised of subunit antigens, adjuvants and microneedle skin delivery: An application to influenza B/Colorado/06/2017

This work introduces VaxiPatch, a novel vaccination system comprised of subunit glycoprotein vaccine antigens, adjuvants and dermal delivery. For this study, rHA of influenza virus B/Colorado/06/2017 was incorporated into synthetic virosomes, and adjuvant liposomes were formed with QS-21 from Saponaria quillaja, with or without the synthetic TLR4 agonist 3D – (6-acyl) PHAD. These components were concentrated and co-formulated into trehalose with dye. Dermal delivery was achieved using an economical 37-point stainless steel microneedle array, designed for automated fill/finish by microfluidic dispensers used for mass production of immunodiagnostics. Vaccine and adjuvant are deposited to form a sugar glass in a pocket on the side of each of the tips, allowing skin penetration to be performed directly by the rigid steel structure. In this study, Sprague Dawley rats (n = 6 per group) were vaccinated by VaxiPatches containing 0.3 µg of rHA, 0.5 µg QS-21 and 0.2 µg 3D – (6-acyl) PHAD and dye, resulting in antigen-specific IgG titers 100-fold higher than 4.5 µg of FluBlok (p = 0.001) delivered intramuscularly. Similarly, hemagglutination inhibition titers in these animals were 14-fold higher than FluBlok controls (p = 0.01). Non-adjuvanted VaxiPatches were also compared with rHA virosomes injected intramuscularly. Accelerated shelf life studies further suggest that formulated virosomal antigens retain activity for at least two months at 60° C. Further, co-formulation of a dye could provide a visible verification of delivery based on the temporary pattern on the skin. A room-temperature-stable vaccination kit such as VaxiPatch has the potential to increase vaccine use and compliance globally.

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Keywords:  VaxiPatch™, Influenza virus rHA subunit antigen, QS-21 and PHAD adjuvants, Microneedle array, Point-of care vaccination, α-trehalose dihydrate (Pfanstiehl, T104-4)

Thomas J. Ellison, George C. Talbott, Daniel R. Henderson, VaxiPatch™, a novel vaccination system comprised of subunit antigens, adjuvants and microneedle skin delivery: An application to influenza B/Colorado/06/2017, Vaccine,
Volume 38, Issue 43, 2020, Pages 6839-6848, ISSN 0264-410X, https://doi.org/10.1016/j.vaccine.2020.07.040.