Mucosal vaccination, i.e., vaccine administration through mucosal surfaces such as the oral or nasal routes continues to be an important goal in the field of vaccinology. 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 including tightly juxtaposed cells, and harsh vaccine-degrading environments such as 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 two different delivery systems will be presented. First, I will describe our efforts to engineer and transform pollen grains from the bane of allergies into ‘trojan horses’ for oral vaccination. 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 vaccine 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. Importantly, the anti-ovalbumin antibody levels induced by lycopodium spores were found to be superior than that induced by the use of cholera toxin (CT) as a control adjuvant. This finding is important because CT although is considered a gold standard amongst oral adjuvants, but it is inherently toxic to humans. Lycopodium spores on the other hand are potentially safe and more effective. The second system that I will discuss 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.