(187c) Pollen Grains, Gold Nanoparticles and Microneedles: Delivery Systems for Mucosal Vaccination

Mucosal vaccination, i.e., vaccine administration through the mucosal surfaces such as the oral or nasal routes continues to be an important goal. This is because mucosal vaccination is needle-free, painless, child-friendly and can be self-administered. Furthermore, from a functional perspective, delivery of vaccines through mucosal surfaces can additionally induce mucosal immunity, which can help to combat pathogens on mucosal surfaces before they can cause infection. However, mucosal barriers such as the tightly juxtaposed cells and the harsh vaccine-degrading environment in the stomach, make mucosal vaccination challenging.

This presentation describes our efforts to engineer micro and nano-systems for vaccine delivery across the mucosal surfaces. Engineering and characterization of three different delivery systems will be presented. First, our efforts to engineer and transform pollen grains from the bane of allergies into ‘trojan horses’ for oral vaccination will be presented. Our results show that native plant matter from lycopodium spores can be removed to create allergen-free durable empty microcapsules that can be filled with vaccine antigens. In vivo evaluation of this novel delivery approach using ovalbumin as a model antigen has shown that high levels of anti-ovalbumin antibodies can be induced in mouse serum and fecal matter, indicative of systemic and mucosal immune responses, respectively. The second system that will be discussed relates to engineering of gold nanoparticles as nanocarriers for intranasal vaccination to help develop a universal influenza vaccine. Our studies show that conjugation of the ectodomain of a conserved membrane protein (M2) of the influenza virus to gold nanoparticles can provide protection against lethal influenza challenge in a mouse model. Lastly, use of coated microneedles to deliver antigens into the rabbit oral-cavity-mucosa will be discussed. Our results show that delivery of antigens into the oral cavity can stimulate production of antigen-specific antibodies in saliva. Overall, these delivery systems show potential for vaccine delivery across mucosal surfaces.