Oral vaccination antigen delivery

Increasing the uptake of antigens by enterocytes may represent an alternative means for oral vaccine delivery. It is, however, commonly believed that antigen uptake by enterocytes leads to the production of antigen tolerance rather than immunity (Brayden and Baird 2001). 

The success of vaccination depends primarily on the method of presenting the antigen to the host immune system. Antigens have usually been delivered by parenteral (such as intravenous, intramuscular, intraperito-neal, intradermal, and subcutaneous) administration, but recent studies have shown that other routes of delivery such as intranasal, oral, and transdermal delivery have also been effective. In some cases, vaccination through mucosal routes resulted in better responses in IgA production. Because non-parenteral vaccine delivery presents many obvious advantages, numerous attempts have been made on the development of non-parenteral delivery of vaccines. 

The maximal intestinal immunization can be achieved by intra-Peyer s patch immunization, and thus this method can be used to screen oral vaccine candidate antigens without the added complication of simultaneously testing oral-delivery systems. Immunization of subjects against Helicobacter pylori by intra-Peyer s patch resulted in an 84-91% reduction in H. pylori infection compared with unimmrmized controls. The therapeutic efficacy of the recombinant H. pylori urease vaccine in mice was shown to be comparable with that achieved with the combined anti-biotic/antacid treatment in humans. The oral vaccination is preferred to conventional treatment of ulcers because it is a very simple and quick procedure compared with long-term conventional treatment. In addition, vaccines use the defense mechanisms of the body to establish long-lasting immunity. ... 

Live Attenuated Organisms. Live attenuated bacteria and viruses have been used not only as vaccines but also as a delivery system that elicits humoral, mucosal, and cellular immune responses against exogenous antigens. Since the success with live attenuated oral vaccines against tuberculosis and polio more than 3 decades ago, a number of live attenuated microorganisms have been used as antigen-delivery systems. Live vaccines are relatively easy and cheap to manufacture, because they do not require purification of... 

Liposomes are vesicles composed of naturally occurring or synthetic phopholipids. The bilayer structure can be single- or multicompartment. The size can also vary from smaller than 1pm to larger than 10 pm. When negatively charged lipid molecules, which form liposomes, interact with divalent cations, a solid, multilayered, crystallaine structure called cochleate is formed. Because liposomes and cochleates can protect antigens from the GI tract and deliver them to the Peyer s patches, they have been exploited as an effective delivery system for oral vaccination. 

Roberts, M. Chatfield, S.N. Dougan, G. Salmonella as Carriers of Heterologous Antigens, In Novel Delivery Systems for Oral Vaccines O Hagan, D.T., Ed. CRC Press Inc. Ann Arbor, MI, 1994 27-58. 

Microspheres have also shown potential as carriers for oral vaccine delivery. The protective polymer coating of microspheres is believed to partially shield the antigens from destructive pH of the stomach, and the high levels of proteases and bile salts in the intestine. Furthermore, microspheres smaller than 10 pm in diameter are thought to be at least partially taken up from the intestine into Peyer s patches where they can induce both mucosal and systemic immune responses. " ... 

De Smet R, Demoor T, Verschuere S, Dullaets M, Ostroff GR, Lecletcq G, et al. beta-Glucan microparticles ate good candidates for mucosal antigen delivery in oral vaccination. J Control Release 2013 172(3) 671—8. 

R. De Smet, T. Demoor, S. Verschuere, M. Dullaers, G.R. Ostroff, G. Leclercq, L. Allais, C. Pilette, M. Dierendonck, B.G. De Geest, C.A. Cuvelier, -Glucan microparticles are good candidates for mucosal antigen delivery in oral vaccination, J. Controlled Release, 172,671-678, 2013. 

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