High-density microprojection array delivery to rat skin of low doses of trivalent inactivated poliovirus vaccine elicits potent neutralising antibody responses

To secure a polio-free world, the live attenuated oral poliovirus vaccine (OPV) will eventually need to be replaced with inactivated poliovirus vaccines (IPV). However, current IPV delivery is less suitable for campaign use than OPV, and more expensive. We are progressing a microarray patch delivery platform, the Nanopatch, as an easy-to-use device to administer vaccines, including IPV. The Nanopatch contains an ultra-high density array (10,000/cm(2)) of short (similar to 230 mu m) microprojections that delivers dry coated vaccine into the skin. Here, we compare the relative immunogenicity of Nanopatch immunisation versus intramuscular injection in rats, using monovalent and trivalent formulations of IPV. Nanopatch delivery elicits faster antibody response kinetics, with high titres of neutralising antibody after just one (IPV2) or two (IPV1 and IPV3) immunisations, while IM injection requires two (IPV2) or three (IPV1 and IPV3) immunisations to induce similar responses. Seroconversion to each poliovirus type was seen in 100% of rats that received similar to 1/40th of a human dose of IPV delivered by Nanopatch, but not in rats given similar to 1/8th or similar to 1/40th dose by IM injection. Ease of administration coupled with dose reduction observed in this study suggests the Nanopatch could facilitate inexpensive IPV vaccination in campaign settings.