Uniform-sized water-in-oil vaccine formulations enhance immune response against Newcastle disease and avian influenza in chickens

- Uniform-sized emulsion was prepared by membrane emulsification technique.
- Uniform-sized emulsion showed low initial release and a faster release rate.
- Uniform-sized emulsion induced higher antibodies.
- Uniform-sized emulsion induced significantly greater ratio of CD8+ to CD4+ T cells.
- Uniform-sized emulsion induced more CD4+CD8+ double positive (DP) T cells.

Water-in-oil (W/O) emulsion is one of the best "one-shot" delivery system for antigen to generate high and durable antibody response. Here a facile method using premixed Shirasu Porous Glass (SPG) membrane emulsification technique was employed to fabricate uniform-sized emulsion and mechanical stirring was employed to prepare non-uniform-sized emulsion as control. In release kinetics studies, uniform-sized emulsion showed low initial release, and during the followed 17 days, uniform-sized emulsions released antigen faster than emulsions of non-uniform size. In addition, vaccination studies against Newcastle disease virus (NDV) and avian Influenza virus (AIV) demonstrated that emulsion of uniform size induced higher HI antibodies and antigen-specific IgG titers. Furthermore, chickens vaccinated with emulsion of uniform size had a significantly greater ratio of CD8+ T cells to CD4+ T cells and a higher percentage of CD8+CD4+ T cells. Taken together, these results indicated that emulsion of uniform size induced a more potent immune response than emulsion prepared by mechanical stirring, and warranted the use of SPG membrane emulsification technique in generating new avian vaccines.