Edible Vaccines Against COVID-19? Another Case of Genetic Engineering Déjà vu

Recent reports indicate that plant scientists in Mexico and Canada are working to produce “edible” vaccines against COVID-19. 

But the idea that fruits or veggies could be genetically engineered (GE) to produce edible vaccines that could be easily shipped, stored and administered to people all over the world, especially in developing countries, has already been debunked…by the originator of the edible vaccine idea himself, Charles Arntzen. Dr. Arntzen, once he had overcome his naïveté about how safe and effective vaccines are actually made, came “to regret coining the term” edible vaccine at all.

So why would a new generation of plant scientists plow ahead on a path deemed a dead end by a respected plant scientist who had spent 25 years in the field and ultimately decided that his edible vaccine idea had been a bad one?

Could these young scientists be unaware of Arntzen’s body of work? I certainly hope not since science builds upon previous science and reading the peer-reviewed literature on a subject one plans to conduct their own research into should be the first step one should take in embarking on a scientific career path.

But, just in case these young scientists are not aware of Arntzen, his work on “edible vaccines,” and his subsequent work with the traditional vaccine industry that led to his regret concerning edible vaccines, here (below) is a brief review.  

Origins of the Edible Vaccine Notion  

Back in the 1990s, Charles Arntzen (most recently professor with the Center for Infectious Diseases and Vaccinology, the Biodesign Institute at Arizona State University, now retired) coined the term “edible vaccines” to describe bananas and other produce items genetically engineered (GE) to produce antigens representing specific disease pathogens. Consuming these GE fruits and veggies, Arntzen hypothesized, would induce production of antigen-specific antibodies in those who ate them, antibodies that would immunize those consumers against that particular disease…hence the moniker “edible vaccines.” 

Arntzen’s idea was to leverage the relatively low cost of producing GE proteins in plants to produce low-cost vaccines in fruits like bananas—which would not require the expensive “cold chains” necessary for transporting and storing traditional vaccines nor technically trained health professionals to administer injections—and deliver them to the developing world.

Arntzen spent the better part of the 1990s trying to reduce his idea to practice, bananas serving as a particular focus and one that “attracted extensive interest in the press.”

Arntzen’s Abandonment of the Edible Vaccine Area of Research

Arntzen has since admitted he had been naïve back then, having ignored the “rigorous regulatory requirements that government agencies and the vaccine industry follow to give us today’s highly effective and wonderfully safe vaccines.” He was less naïve by fifteen years ago when he and his colleagues informed edible vaccine enthusiasts at a scientific conference that “[w]hile it was frequently mentioned that plant-based protein production is highly cost effective…production costs may represent only a small part of the cost of a vaccine. GMP (Good Manufacturing Practice) requirements, purification, quality controls for vaccine approval are major cost factors in (human) vaccine production.” 

By five years ago, Arntzen admitted that “plant-to-plant variations will require careful (and expensive) analytical controls to determine exact dosages of antigen….” [And I would extend this requirement to fruit-to-fruit and veggie-to-veggie variation as fruits and veggies continue physiological and biochemical processes after they have been harvested from plants, for example the cell elongation process that can proceed in a cut onion during storage in your refrigerator.]

By 2015 Arntzen noted that the edible vaccine concept “may have attracted attention in the plant biology realm, but it probably has been much more counterproductive in the traditional vaccine industry.” It was by then that he had “come to regret coining the term” edible vaccine in the first place.

The More Recent Scientific Literature

A recent review article in the Journal of Immunology Research (Criscuolo et al. 2019) still lists the “lack of a proper dosing strategy” as one of the major problems with the “edible vaccine” concept. Other cons that Criscuolo et al. mention in relation to edible vaccines include “improper glycosylation, low antigen expression yields, unstable antigen expression.”

So Why the Resurgence of the Edible Vaccine Concept Now?

So why is Cornell’s Alliance for Science now asking if “we could eat a GM [AKA GE] fruit that directly confers immunity” to COVID-19? And why are young plant biologists, like Daniel Garza Garcia (Institute of Biotechnology of the Autonomous University of Nuevo Leon, Mexico) and Allyson MacLean (University of Ottawa, Canada) now touting edible vaccines against COVID-19?

Post-harvest plant physiology and the “lack of a proper dosing strategy” still pose very real problems that need to be solved before this edible vaccine “notion” can be reduced to practice. Arntzen had given up on this notion by at least 5 years ago, and had moved on to another strategy: producing high levels of antigens in GE plants but then—instead of eating the fruit or veggies directly from those GE plants—purifying the antigens from their GE plant factories and using those purified antigens to “follow the regulatory pathways now well established for subunit vaccines….” Arntzen and his collaborators, as well as others, have had success utilizing this “plant-made pharmaceuticals” strategy in developing Ebola therapeutics, for example.

Based on the accounts I’ve read about current research being conducted with the goal of developing edible vaccines against COVID-19, I’d say (IMHO) that these projects are at the naïve stage Arntzen was at back in the early 1990s.

Naïve is Not What We Need in Response to the COVID-19 Pandemic

We don’t have time for young scientists to rediscover the various problems with delivering an “edible COVID-19 vaccine” to a real and desperate world. Instead, our scientific focus should be on supporting efficient, effective work—based on less naïve strategies—toward producing COVID-19 vaccines.    

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