Foods as Production and Delivery Vehicles for Human Vaccines

Abstract

Vaccination is a great asset for eradication of infectious diseases in humans and animals. With the prevalence of antibiotic resistant bacterial strains and an alarming increase in new and re-emerging pathogens, the need for vaccination continues to be a high priority for mammalian diseases. In the last several years, a novel approach for developing improved mucosal subunit vaccines has emerged by exploiting the use of genetically modified plants. It has been demonstrated that plant-derived antigens are functionally similar to conventional vaccines and can induce neutralizing antibodies in mammalian hosts. Using genetically engineered plants for the production of immunogenic peptides also provides a new approach for the delivery of a plant-based subunit vaccine, i.e., oral delivery, provided these immunogenic peptides are expressed in an edible part of the plant, such as grain or fruit. Thus, food crops can play a significant new role in promoting human health by serving as vehicles for both production and delivery of vaccines.

• food crops
• transgenic plants
• plant-based vaccines
• oral edible vaccines

Key teaching points:

• Via genetic engineering and molecular biology, genes encoding immunogenic proteins of an infectious agent can be transferred into the nuclear genome of a plant system such that the plant is capable of producing the desired immunogenic protein subunit vaccines.

• The production of antigens in genetically engineered plants provides an inexpensive source of edible vaccines and, in turn, increases the value of plants as novel sources of medicinal drugs.

• Edible vaccines against cholera toxin B subunit, hepatitis B surface antigen, E. coli heat labile enterotoxin, and Norwalk virus capsid protein have been developed and tested for efficacy in animal and human trials. Immunologic responses were provoked in both mice and humans.

• A plant-based oral subunit vaccine for the respiratory syncytial virus has been developed. This virus is a serious pathogen that causes bronchiolitis and pneumonia-type diseases in all human age groups and is a leading cause of viral lower respiratory tract illness in infants and children worldwide.

• This new area of agriculture, referred to as “biopharming,” will provide new value to crops grown for the sole purpose of producing and/or delivering biopharmaceutical or medicinal products.

Key teaching points:

• Via genetic engineering and molecular biology, genes encoding immunogenic proteins of an infectious agent can be transferred into the nuclear genome of a plant system such that the plant is capable of producing the desired immunogenic protein subunit vaccines.

• The production of antigens in genetically engineered plants provides an inexpensive source of edible vaccines and, in turn, increases the value of plants as novel sources of medicinal drugs.

• Edible vaccines against cholera toxin B subunit, hepatitis B surface antigen, E. coli heat labile enterotoxin, and Norwalk virus capsid protein have been developed and tested for efficacy in animal and human trials. Immunologic responses were provoked in both mice and humans.

• A plant-based oral subunit vaccine for the respiratory syncytial virus has been developed. This virus is a serious pathogen that causes bronchiolitis and pneumonia-type diseases in all human age groups and is a leading cause of viral lower respiratory tract illness in infants and children worldwide.

• This new area of agriculture, referred to as “biopharming,” will provide new value to crops grown for the sole purpose of producing and/or delivering biopharmaceutical or medicinal products.

We wish to acknowledge the funding received from USDA-NRI and Illinois Council for Food and Agriculture Research (C-FAR) that allowed us to pursue the work described in this review. We also like to acknowledge the research contributions previously made by Dr. Leslie L. Domier (USDA-ARS, Department of Crop Science), Dr. Jagdeep Sandhu (Department of Crop Science), and Dr. Mark Osadjan.