PowderJectTM DNA Vaccines in Domestic Pigs

Abstract

PowderJect Vaccines (PJV) utilizes proprietary particle technologies to formulate and deliver both conventional and DNA vaccines to cells in the skin, especially the epidermis. PowderJect products are intended for human use, however much of the preclinical work on these vaccines has been conducted in domestic pigs because pig’s skin is the preferred model for human skin. PowderJect DNA vaccines employ particle-mediated gene transfer (PMGT) that provides intracellular DNA delivery which is much more efficient than delivery modes that require DNA uptake from the extracellular compartment. Influenza A virus is a common pathogen for both pigs and humans. A PJV-DNA vaccine encoding an influenza A HI hemagglutinin (HA) was used to immunize pigs in parallel to an oiladjuvanted inactivated-virus vaccine delivered by intramuscular injection. Both vaccines showed significant responses when assayed for anti-HA ELISA or hemagglutination-inhibition (HI) titers, though the conventional vaccine induced higher titer responses than the DNA vaccine. Vaccinated animals were challenged with homologous virus, and the progression of infection was analyzed by measuring clinical symptoms, body temperature and nasal virus shed. Neither clinical symptoms, nor body temperature proved reliable measures of the course of infection. Virus shed, however distinguished the vaccinated groups from the unvaccinated control group. Both vaccinated groups showed an approximately 2-log reduction of peak virus shed, however the DNA vaccinated animals cleared virus more quickly than the animals that received conventional vaccine.