Oral vaccines: new needs, new possibilities

Abstract

Vaccination is an important tool for handling healthcare programs both in developed and developing countries. The current global scenario calls for a more-efficacious, acceptable, cost-effective and reliable method of immunization for many fatal diseases. It is hoped that the adoption of oral vaccines will help to provide an effective vaccination strategy, especially in developing countries. Mucosal immunity generated by oral vaccines can serve as a strong first line of defense against most of the pathogens infecting through the mucosal lining. Advances in elucidating the mechanism of action of oral vaccines will facilitate the design of more effective, new generation vaccines. There are promising developments in the use of different agents to effectively deliver the vaccine candidate. It is hoped that ongoing research may be able to set another cardinal point, after polio vaccine, in eradicating infectious diseases.

Stable Chromosomal Expression of Shigella flexneri 2a and 3a O-Antigens in the Live Salmonella Oral Vaccine Vector Ty21a

“…Such an approach could further facilitate the deployment of Ty21a-vectored vaccines in less-developed regions and in emergency mass vaccination campaigns. Additionally, needle-free administration would increase acceptability (and thus compliance) and enhance the occupational safety of vaccinators and other health care providers (29).…”

Strategies in Oral Immunization

“…Several advantages including inexpensive means of expressing proteins, elimination of the risk of contamination with animal pathogens, and a heat-stable environment, indicate that the production of vaccines in plants will be successful (Aziz et al 2007). Moreover, plants are able to carry out post-translational modifications, can be produced in large quantities, and can express multiple transgenes at one time, giving thus the potential for using one formulation to deliver several vaccines.…”

“…In addition, orally administered vaccines must be taken up and presented to appropriate cells of the immune system. This process is inefficient, necessitating the administration of large doses of antigen, and may be made worse by the presence of food or chyme in the GIT, which may entrap vaccines preventing the necessary proximity between the vaccine and the GIT epithelia for vaccine uptake (Russell-Jones 2000; Aziz et al 2007). Oral tolerance, whereby antigens are recognized as food antigens or normal flora instead of eliciting protective immune responses, may also be observed against orally administered soluble antigens (Mestecky et al 2007).…”

“…Immunization is one of the most effective public health interventions (Aziz et al 2007). Traditionally vaccines play a prophylactic role, with the development of treatment vaccines [e.g.…”

Bilosomes Based Drug Delivery System

“…The present concept of vaccination is based on invasive parenteral method which is not completely effective against number of diseases [19]. These traditional needle-based vaccination methods suffer from various drawbacks, like the need for trained personnel to administer vaccines, patient inconvenience and the associated risk of needle-borne infections (AIDS, hepatitis, etc.)…”