Oral vaccination delivery systems

Approaches and Different Oral Vaccine Delivery Systems. 201... 

Mucosal adjuvant and vaccine delivery system development is an area of importance for improving public health. Mucosal immunization can serve in the future in increasing mucosal immune function, induction of protective immunity against infections, and induction of tolerance or modifying autoimmune disorders, allergies, and autoimmune diseases. Development of oral vaccines would have large implications for rural and remote populations where access to trained medical staff to administer vaccines by injection can be lacking. 

Niosomes are non-ionic surfactant vesicles. They have been used to develop a vaccine-delivery system by peroral and oral routes. Ovalbumin was encapsulated in various lyophilized niosome preparations consisting of sucrose esters, cholesterol, and dicetyl phosphate. Encapsulation of ovalbumin into niosomes consisting of 70% stearate sucrose ester and 30% pal-mitate sucrose ester (40%i mono-, 60% di/triester) resulted in a significant increase in antibody titers in serum, saliva, and intestinal washings. ... 

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. " ... 

Eldridge, J. H., Gilley, R. M., Staas, J. K., Moldoveanu, Z., Meulbroek, J. A. and Tice, T. R., Biodegradable microspheres vaccine delivery system for oral immunization, Curr. Topics Microbiol. Immunol, 146, 59-66 (1989). 

Chitosan microparticles have also been fabricated for oral vaccination, even though it is difficult to avoid the degradation of vaccine in the gut region. The in-vivo uptake of vaccine by murine Peyer s patches was remarkably good, proving it to be an efficient tool in vaccine delivery system [150]. 

Due to the limitations with the gastrointestinal tract, there are few studies available on chitosan-based delivery systems for oral vaccine delivery (Table 1). Van der Lubben et al. [66] were among the first to demonstrate that chitosan microparticles with a particle size smaller than 10 pm, incorporated with the model protein OVA as well as diphtheria toxoid (DT), were taken up by the Peyer s patch after intragastric administration to mice. A dose-dependent immune reaction was observed for mice vaccinated with different doses of DT associated to chitosan microparticles [67]. It was also observed that the immune response started only 1 week after the boosting, indicating the formation of memory cells after priming. 

Lamphear, B.J., Jilka, J.M., Kesl, L., Welter, M., Howard, J.A., and Streatfield, S.J. (2004). A corn-based delivery system for animal vaccines an oral transmissible gastroenteritis virus vaccine boosts lactogenic immunity in swine. Vaccine 22(19) 2420-2424. 

A corn-based delivery system for animal vaccines an oral transmissible gastroenteritis virus vaccine boosts lactogenic immunity in swine. Vaccine 22(19) 2420-2424. 

The most potent mucosal adjuvants have been shown to be the toxins derived from Vibrio cholerae or Escherichia coli, which should not be surprising since these organisms invade the body through the GI tract. Obviously too toxic for human use because they are the source of cholera or diarrhoea, heat labile enterotoxins have been tested in mice and shown to be potent adjuvants for orally or nasally administered influenza vaccine. The potency of heat-labile enterotoxin mutants may also be enhanced by formulation into bioadhesive particulate delivery systems, and this is an area under current exploration. 

Liposomes (see Chapter 9) have been used to deliver vaccines and have been observed to have immunostimulant activity. When administered orally liposomes with encapsulated antigens have been claimed to provide protection from the gastric proteolytic enzymes. Liposomes also have potential as mucosal delivery systems... 

O Hagan, D.T. (1994). Novel Delivery Systems for Oral Vaccines. CRC Press, Boca Raton, FL. 

---