Induction of a Protective Antibody Response to Foot and Mouth Disease Virus in Mice Following Oral or Parenteral Immunization with Alfalfa Transgenic Plants Expressing the Viral Structural Protein VP1

Abstract

The utilization of transgenic plants expressing recombinant antigens to be used in the formulation of experimental immunogens has been recently communicated. We report here the development of transgenic plants of alfalfa expressing the structural protein VP1 of foot and mouth disease virus (FMDV). The presence of the transgenes in the plants was confirmed by PCR and their specific transcription was demonstrated by RT-PCR. Mice parenterally immunized using leaf extracts or receiving in their diet freshly harvested leaves from the transgenic plants developed a virus-specific immune response. Animals immunized by either method elicited a specific antibody response to a synthetic peptide representing amino acid residues 135-160 of VP1, to the structural protein VP1, and to intact FMDV particles. Additionally, the immunized mice were protected against experimental challenge with the virus. We believe this is the first report demonstrating the induction of a protective systemic antibody response in animals fed transgenic plants expressing a viral antigen. These results support the feasibility of producing edible vaccines in transgenic forage plants, such as alfalfa, commonly used in the diet of domestic animals even for those antigens for which a systemic immune response is required.

Medical molecular farming: production of antibodies, biopharmaceuticals and edible vaccines in plants

“…Plant-expressed antigens have been shown to able to induce mucosal and serum immune responses when administered parenterally or orally to experimental animals and, in some test cases, they have offered protection against a subsequent pathogen challenge or challenge model 14,16,[19][20][21][22][23][24] . A few of these vaccine candidates have been successfully tested in clinical trials or, where appropriate, in commercial or native animal trials [25][26][27][28][29][30] .…”

“…It is also important that any vaccine component should be present in its native form in the transgenic plant tissue. This has been assessed in several cases by examining the size of the synthesized protein, its ability to form higher-order complexes that mirror microbial or viral structures and, where relevant, by showing an enzymatic or receptor-binding activity 14,[16][17][18]22,24,29 .…”

Biotechnological leap in biopharmaceuticals: Current status and challenges ahead

“…There was also development of another vaccine which followed the first one by expression of hepatitis B surface antigens in plants [57]. Now there are many different types of proteins which are successfully expressed in plants, such as E. coli heatlabile enterotoxin antigen [58], granulocyte macrophage colony stimulating factor [59], human serum albumin [60], enkephalins [61] and glucocerebrosidase, surface antigen of Norwalk virus [53], VP1 antigen from foot and mouth disease virus [62,63], B subunit of cholera toxin [54], antigen of rabies virus [51], transmissible gastroenteritis coronavirus's S protein [64,65], G and F proteins of respiratory syncytial virus [66], rotaviral VP6 protein [67], rinderpest [68], and the measles [69] from the major surface antigen of Plasmodium falciparum (an epitope) [70] and virus hemagglutinin proteins. Some plant based vaccines under clinical trials are given in Table 2.…”

Transgenic Plant Vaccine: A Breakthrough in Immunopharmacotherapeutics

“…Since then, several proteins of different origin have been expressed in plants. These include Escherichia coli heat-labile enterotoxin antigen [11], Enkephalins [12], Human serum albumin [13], Glucocerebrosidase and granulocyte macrophage colony stimulating factor [14], Norwalk virus surface protein [15], VP1 antigen from foot and mouth disease virus [16,17], cholera toxin B subunit [18], Rabies antigen [19], the S protein of transmissible gastroenteritis coronavirus [20,21], Respiratory synctial virus G and F proteins [8,22], the VP6 protein of rotavirus [23], the measles [24] and Rinderpest [25], virus hemagglutinin proteins and an epitope from the major surface antigen of Plasmodium falciparum [26].…”