Immunological aspects of using plant cells as delivery vehicles for oral vaccines

Abstract

Genetically engineered plants can be used for the biomanufacture and delivery of oral vaccines. Although a myriad of antigens have been produced using this approach, improving our knowledge of their oral immunogenic properties is a priority as this aspect has not been well researched. Some studies have provided evidence of a higher immunogenic activity for antigens that were orally administered in the form of plant-based vaccines in comparison with conventional pure antigens. The characteristics of the plant-derived vaccines that may influence oral immunogenicity are identified and discussed in this review. Among the hypotheses explaining these immunogenic properties are the following: bioencapsulation favors antigen uptake and displays a resistance to degradation; plant metabolites exert adjuvant activity; plant compounds, such as polysaccharides, exert mucoadhesive properties; differential glycosylation conferred by the plant cell machinery enhances immunogenicity. Perspectives on how these hypotheses may be assessed are examined.

Keywords::

• adjuvant
• bioencapsulation
• glycosylation
• low cost vaccine
• oral immunogenicity
• secondary metabolites

Acknowledgements

Omar González corrected the English version of the manuscript.

Financial & competing interests disclosure

Projects from the group are funded by grants from CONACYT (102109/56980), PROMEP-2010 to Bioprocess CA. The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Plant-based vaccines offer low cost and the absence of human pathogens, which account for their potential to yield new convenient vaccines.

• The development of oral plant-based vaccines represents a goal that requires a better understanding of their immunological properties.

• There is evidence of higher immunogenic activity for antigens orally administered in the form of plant-based vaccines in comparison to conventional pure antigens.

• Features of plant-based vaccines are analyzed to postulate the mechanisms involved in the immunogenic properties of orally administered plant-based vaccines.

• The discussed aspects include the effects of plant cell bioencapsulation on antigen uptake and resistance to degradation, the presence of secondary metabolites, mucoadhesive compounds and plant glycans.

Notes