(51d) Pollen Grains for Oral Vaccination | AIChE

(51d) Pollen Grains for Oral Vaccination

Authors 

Gill, H. S. - Presenter, Texas Tech University
Atwe, S., SutroVxx
Ma, Y., Texas Tech University



The oral route remains a highly desirable method of vaccination. Here we propose the use of pollen grains (PGs) as a novel material for oral vaccine delivery. PGs have the unique property that their outer shell is highly resistant that remains intact even in the acid- and enzyme-rich environment of the stomach. Furthermore, PGs could perhaps be persorbed as intact particles across the intestinal epithelium, enabling PGs to be used as microshuttles for antigen transport. PGs have been used in traditional medicine and as nutritive material in various civilizations providing anecdotal evidence to the safety of PGs for human consumption. We present the first study demonstrating the potential of PGs for oral vaccination. 

Lycopodium clavatum spores (LSs) were investigated as a representative PG. Ovalbumin (OVA) was used as the model antigen. LSs were chemically treated to remove native proteins, lipids and other biomolecules. Systemic immune response was compared between the LS, cholera toxin (CT) and its B subunit (CTB). Balb/c mice were immunized orally using the different formulations at days 0 and 28. Blood was collected at days 0, 28 and 56 to determine serum immunoglobulin G (IgG) levels and Th1 and Th2 response using ELISA. 

Chemical treatment of LSs was effective in removal of native plant material. Scanning electron micrographs of LSs before and after treatment provide a visual indication that processed LSs are devoid of plant biomolecules. OVA was successfully loaded into the spore interior as demonstrated by the confocal micrograph of LSs. ELISA for serum showed that mice immunized with 100 µg OVA+5mg LSs had IgG levels even higher than the group immunized with 5 mg OVA+5µg cholera toxin (CT). This is exciting data because CT is the current gold standard in oral mucosal vaccination and our study shows that LSs are even superior to CT. The strong adjuvant effect of spores has been reproduced by us in multiple independent studies. In conclusion, we present the first study demonstrating the adjuvant effect of LSs for oral vaccination.