Suppository-mediated DNA immunization induces mucosal immunity against bovine herpesvirus-1 in cattle

Mucosal surfaces are the primary sites for the transmission of infectious agents including viruses, so effective vaccines generally should induce mucosal immunity. Furthermore, noninvasive delivery is desirable because of the ease of application, the high degree of patient compliance, and the improved safety for patients and clinicians due to the elimination of needles. Unfortunately, most of the conventional vaccines are parenterally administered and result in systemic rather than mucosal immunity. Here we present the first report of mucosal immunity by noninvasive DNA immunization in a target species. As an approach to induce mucosal immunity against bovine herpesvirus-1, cows were immunized intravaginally with suppositories containing plasmid coding for glycoprotein D. Serum IgG, as well as IgA both in the serum and in the nasal fluids, were detected, which supports the contention of a common mucosal immune system. This level of immunity was of sufficient magnitude to minimize weight loss and significantly reduce the duration of virus shedding after intranasal viral challenge, which demonstrates the efficacy of suppository-based administration of DNA vaccines to target species. As this is a very practical method of delivery, it has great potential to be applied as vaccine or therapy in a variety of species.