Scientists Are Growing an Edible Cholera Vaccine in Rice
The world's attention has been focused on the coronavirus crisis but Yemen, Bangladesh and many others countries in Asia and Africa are also in the grips of another pandemic: cholera. The current cholera pandemic first emerged in the 1970s and has devastated many communities in low-income countries. Each year, cholera is responsible for an estimated 1.3 million to 4 million cases and 21,000 to 143,000 deaths worldwide.
Immunologist Hiroshi Kiyono and his team at the University of Tokyo hope they can be part of the solution: They're making a cholera vaccine out of rice.
"It is much less expensive than a traditional vaccine, by a long shot."
Cholera is caused by eating food or drinking water that's contaminated by the feces of a person infected with the cholera bacteria, Vibrio cholerae. The bacteria produces the cholera toxin in the intestines, leading to vomiting, diarrhea and severe dehydration. Cholera can kill within hours of infection if it if's not treated quickly.
Current cholera vaccines are mainly oral. The most common oral are given in two doses and are made out of animal or insect cells that are infected with killed or weakened cholera bacteria. Dukoral also includes cells infected with CTB, a non-harmful part of the cholera toxin. Scientists grow cells containing the cholera bacteria and the CTB in bioreactors, large tanks in which conditions can be carefully controlled.
These cholera vaccines offer moderate protection but it wears off relatively quickly. Cold storage can also be an issue. The most common oral vaccines can be stored at room temperature but only for 14 days.
"Current vaccines confer around 60% efficacy over five years post-vaccination," says Lucy Breakwell, who leads the U.S. Centers for Disease Control and Prevention's cholera work within Global Immunization Division. Given the limited protection, refrigeration issue, and the fact that current oral vaccines require two disease, delivery of cholera vaccines in a campaign or emergency setting can be challenging. "There is a need to develop and test new vaccines to improve public health response to cholera outbreaks."
A New Kind of Vaccine
Kiyono and scientists at Tokyo University are creating a new, plant-based cholera vaccine dubbed MucoRice-CTB. The researchers genetically modify rice so that it contains CTB, a non-harmful part of the cholera toxin. The rice is crushed into a powder, mixed with saline solution and then drunk. The digestive tract is lined with mucosal membranes which contain the mucosal immune system. The mucosal immune system gets trained to recognize the cholera toxin as the rice passes through the intestines.
The cholera toxin has two main parts: the A subunit, which is harmful, and the B subunit, also known as CTB, which is nontoxic but allows the cholera bacteria to attach to gut cells. By inducing CTB-specific antibodies, "we might be able to block the binding of the vaccine toxin to gut cells, leading to the prevention of the toxin causing diarrhea," Kiyono says.
Kiyono studies the immune responses that occur at mucosal membranes across the body. He chose to focus on cholera because he wanted to replicate the way traditional vaccines work to get mucosal membranes in the digestive tract to produce an immune response. The difference is that his team is creating a food-based vaccine to induce this immune response. They are also solely focusing on getting the vaccine to induce antibodies for the cholera toxin. Since the cholera toxin is responsible for bacteria sticking to gut cells, the hope is that they can stop this process by producing antibodies for the cholera toxin. Current cholera vaccines target the cholera bacteria or both the bacteria and the toxin.
David Pascual, an expert in infectious diseases and immunology at the University of Florida, thinks that the MucoRice vaccine has huge promise. "I truly believe that the development of a food-based vaccine can be effective. CTB has a natural affinity for sampling cells in the gut to adhere, be processed, and then stimulate our immune system, he says. "In addition to vaccinating the gut, MucoRice has the potential to touch other mucosal surfaces in the mouth, which can help generate an immune response locally in the mouth and distally in the gut."
Cost Effectiveness
Kiyono says the MucoRice vaccine is much cheaper to produce than a traditional vaccine. Current vaccines need expensive bioreactors to grow cell cultures under very controlled, sterile conditions. This makes them expensive to manufacture, as different types of cell cultures need to be grown in separate buildings to avoid any chance of contamination. MucoRice doesn't require such an expensive manufacturing process because the rice plants themselves act as bioreactors.
The MucoRice vaccine also doesn't require the high cost of cold storage. It can be stored at room temperature for up to three years unlike traditional vaccines. "Plant-based vaccine development platforms present an exciting tool to reduce vaccine manufacturing costs, expand vaccine shelf life, and remove refrigeration requirements, all of which are factors that can limit vaccine supply and accessibility," Breakwell says.
Kathleen Hefferon, a microbiologist at Cornell University agrees. "It is much less expensive than a traditional vaccine, by a long shot," she says. "The fact that it is made in rice means the vaccine can be stored for long periods on the shelf, without losing its activity."
A plant-based vaccine may even be able to address vaccine hesitancy, which has become a growing problem in recent years. Hefferon suggests that "using well-known food plants may serve to reduce the anxiety of some vaccine hesitant people."
Challenges of Plant Vaccines
Despite their advantages, no plant-based vaccines have been commercialized for human use. There are a number of reasons for this, ranging from the potential for too much variation in plants to the lack of facilities large enough to grow crops that comply with good manufacturing practices. Several plant vaccines for diseases like HIV and COVID-19 are in development, but they're still in early stages.
In developing the MucoRice vaccine, scientists at the University of Tokyo have tried to overcome some of the problems with plant vaccines. They've created a closed facility where they can grow rice plants directly in nutrient-rich water rather than soil. This ensures they can grow crops all year round in a space that satisfies regulations. There's also less chance for variation since the environment is tightly controlled.
Clinical Trials and Beyond
After successfully growing rice plants containing the vaccine, the team carried out their first clinical trial. It was completed early this year. Thirty participants received a placebo and 30 received the vaccine. They were all Japanese men between the ages of 20 and 40 years old. 60 percent produced antibodies against the cholera toxin with no side effects. It was a promising result. However, there are still some issues Kiyono's team need to address.
The vaccine may not provide enough protection on its own. The antigen in any vaccine is the substance it contains to induce an immune response. For the MucoRice vaccine, the antigen is not the cholera bacteria itself but the cholera toxin the bacteria produces.
"The development of the antigen in rice is innovative," says David Sack, a professor at John Hopkins University and expert in cholera vaccine development. "But antibodies against only the toxin have not been very protective. The major protective antigen is thought to be the LPS." LPS, or lipopolysaccharide, is a component of the outer wall of the cholera bacteria that plays an important role in eliciting an immune response.
The Japanese team is considering getting the rice to also express the O antigen, a core part of the LPS. Further investigation and clinical trials will look into improving the vaccine's efficacy.
Beyond cholera, Kiyono hopes that the vaccine platform could one day be used to make cost-effective vaccines for other pathogens, such as norovirus or coronavirus.
"We believe the MucoRice system may become a new generation of vaccine production, storage, and delivery system."
A Single Blood Test May Soon Replace Your Annual Physical
The measurement of proteins in one blood test could provide a comprehensive snapshot of a person's health in the near future.
For all the excitement over "personalized medicine" in the last two decades, its promise has not fully come to pass. Consider your standard annual physical.
Scientists have measured thousands of proteins from a single blood test to assess many individualized health conditions at once.
Your doctor still does a blood test to check your cholesterol and gauge your risk for heart disease by considering traditional risk factors (like smoking, diabetes, blood pressure) — an evaluation that has not changed in decades.
But a high-risk number alone is not enough to tell accurately whether you will suffer from heart disease. It just reflects your risk compared to population-level averages. In other words, not every person with elevated "bad" cholesterol will have a heart attack, so how can doctors determine who truly needs to give up the cheeseburgers and who doesn't?
Now, an emerging area of research may unlock some real-time answers. For the first time, as reported in the journal Nature Medicine last week, scientists have measured thousands of proteins from a single blood test to assess many individualized health conditions at once, including liver and kidney function, diabetes risk, body fat, cardiopulmonary fitness, and even smoking and alcohol consumption. Proteins can give a clear snapshot of how your body is faring at any given moment, as well as a sneak preview at what diseases may be lurking under the surface.
"Years from now," says study co-author Peter Ganz of UCSF, "we will probably be looking back on this paper as a milestone in personalized medicine."
We spoke to Ganz about the significance of this milestone. Our interview has been edited and condensed.
Is this the first study of its kind?
Yes, it is. This is a study where we measured 5,000 proteins at once to look for patterns that could either predict the risk of future diseases or inform the current state of health. Previous to this, people have measured typically one protein at a time, and some of these individual proteins have made it into clinical practice.
An example would be a protein called C-reactive protein, which is a measure of inflammation and is used sometimes in cardiology to predict the risk of future heart attacks. But what's really new is this scale. We wanted to get away from just focusing on one problem that the patient may have at a time, whether it's heart disease or kidney disease, and by measuring a much greater number of proteins, the hope is that we could inform the health of ultimately just about every organ in the body or every tissue. It's a step forward for what I would call "a one-stop shop."
"I'm very excited about personalized medicine through proteins as opposed to genes because you get both the nature and nurture."
Three things get me excited about this. One is the convenience for the patient of a single test to determine many different diseases. The second thing is the healthcare cost savings. We estimated what the cost would be to get these 11 healthcare measures that we reported on using traditional testing and the cost was upwards of 3,000 British pounds. And even though I don't know for sure what the cost of the protein tests would ultimately be, [it could come down to about $50 to $100].
The last thing is that the measurement of proteins is part of what people have called personalized medicine or precision medicine. If you look at risk factors across the population, it may not apply to individuals. In contrast, proteins are downstream of risk factors. So proteins actually tell us whether the traditional risk factors have set in motion the necessary machinery to cause disease. Proteins are the worker bees that regulate what the human body does, and so if you can find some anomalies in the proteins, that may inform us if a disease is likely to be ongoing even in its earliest stages.
Does protein testing have advantages over genetic testing for predicting future health risks?
The problem with genomics is that genes usually don't take care of the environment. It's a blueprint, but your blueprint has no idea what you will be exposed to during your lifetime in terms of the environment and lifestyle that you may choose and medications that you may be on. These are things that proteins can account for. I'm very excited about personalized medicine through proteins as opposed to genes because you get both the nature and nurture as opposed to genomics, which only gives you nature but doesn't account for anything else.
Proteins can also be tracked over time and that's not something you can do with genes. So if your behavior improves, your genes won't change, but your proteins will.
Could this new test become a regular feature of your annual physical?
That's the idea. This would be basically almost a standalone test that you could have done every year. And hopefully you wouldn't need other tests to complement this. This could be your yearly physical.
How much more does it need to be validated before it can enter the clinic and patients can trust the results?
This was a proof-of concept study. To really make this useful, we need to expand from 11 measures of health to a hundred or more health insights, to cover the whole body. And we need to expand this to all racial groups. Three of the five centers in the study were European – all Caucasian – so it's one of our high priorities to find groups of patients with better representation of minorities.
When do you expect doctors to be routinely giving this test to patients?
Much closer to five years than 20 years. We're scaling up from 11 disease states to 100, and many of those studies are underway. Results should be done within three to five years.
Do you think insurance will cover it?
Good question. I have been approached by an insurance company that wanted to understand the product better – a major insurer, with the possibility that this could actually be cost saving.
I have to ask you a curveball -- do you think that the downfall of Theranos will make consumers hesitant to trust a new technology that relies on using a single blood sample to screen for multiple health risks?
[Laughs] You're not the first person to ask me that today. I actually got a call from Elizabeth Holmes [in 2008 when I was at Harvard]. I met with her for an afternoon and met her team two more times. I gave them advice that they completely disregarded.
In many ways, what we do is diametrically opposite to Theranos. They had a culture of secrecy, and what we do is about openness. We publish, like this paper in Nature Medicine, to show the scientific details. Our supplement is much longer than the typical academic paper. We reveal everything we know. A lot of the research we do is funded by [the National Institutes of Health], and they have strict expectations about data sharing. So we agree to make the data available on a public website. If there is something we haven't done with the data, others can do it.
So you're saying that this is not another Theranos.
No, God forbid. We hope to be the opposite.
Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.
We Pioneered a Technology to Save Millions of Poor Children, But a Worldwide Smear Campaign Has Blocked It
On left, a picture of white rice next to Golden Rice, and on right, a girl who lost one eye due to vitamin A deficiency.
In a few weeks it will be 20 years that we three have been working together. Our project has been independently praised as one of the most influential of all projects of the last 50 years.
Two of us figured out how to make rice produce a source of vitamin A, and the rice becomes a golden color instead of white.
The project's objectives have been admired by some and vilified by others. It has directly involved teams of highly motivated people from a handful of nations, from both the private and public sector. A book, dedicated to the three of us, has been written about our work. Nevertheless, success has, so far, eluded us all. The story of our thwarted efforts is a tragedy that we hope will soon – finally – reach a milestone of potentially profound significance for humanity.
So, what have we been working on, and why haven't we succeeded yet?
Food: everybody needs it, and many are fortunate enough to have enough, even too much of it. Food is a highly emotional subject on every continent and in every culture. For a healthy life our food has to provide energy, as well as, in very small amounts, minerals and vitamins. A varied diet, easily achieved and common in industrialised countries, provides everything.
But poor people in countries where rice is grown often eat little else. White rice only provides energy: no minerals or vitamins. And the lack of one of the vitamins, vitamin A, is responsible for killing around 4,500 poor children every day. Lack of vitamin A is the biggest killer of children, and also the main cause of irreversible childhood blindness.
Our project is about fixing this one dietary deficiency – vitamin A – in this one crop – rice – for this one group of people. It is a huge group though: half of the world's population live by eating a lot of rice every day. Two of us (PB & IP) figured out how to make rice produce a source of vitamin A, and the rice becomes a golden color instead of white. The source is beta-carotene, which the human body converts to vitamin A. Beta-carotene is what makes carrots orange. Our rice is called "Golden Rice."
The technology has been donated to assist those rice eaters who suffer from vitamin A deficiency ('VAD') so that Golden Rice will cost no more than white rice, there will be no restrictions on the small farmers who grow it, and nothing extra to pay for the additional nutrition. Very small amounts of beta-carotene will contribute to alleviation of VAD, and even the earliest version of Golden Rice – which had smaller amounts than today's Golden Rice - would have helped. So far, though, no small farmer has been allowed to grow it. What happened?
To create Golden Rice, it was necessary to precisely add two genes to the 30,000 genes normally present in rice plants. One of the genes is from maize, also known as corn, and the other from a commonly eaten soil bacterium. The only difference from white rice is that Golden Rice contains beta-carotene.
It has been proven to be safe to man and the environment, and consumption of only small quantities of Golden Rice will combat VAD, with no chance of overdosing. All current Golden Rice results from one introduction of these two genes in 2004. But the use of that method – once, 15 years ago - means that Golden Rice is a 'GMO' ('genetically modified organism'). The enzymes used in the manufacture of bread, cheese, beer and wine, and the insulin which diabetics take to keep them alive, are all made from GMOs too.
The first GMO crops were created by agri-business companies. Suspicion of the technology and suspicion of commercial motivations merged, only for crop (but not enzymes or pharmaceutical) applications of GMO technology. Activists motivated by these suspicions were successful in getting the 'precautionary principle' incorporated in an international treaty which has been ratified by 166 countries and the European Union – The Cartagena Protocol.
The equivalent of 13 jumbo jets full of children crashes into the ground every day and kills them all, because of vitamin A deficiency.
This protocol is the basis of national rules governing the introduction of GMO crops in every signatory country. Government regulators in, and for, each country must agree before a GMO crop can be 'registered' to be allowed to be used by the public in that country. Currently regulatory decisions to allow Golden Rice release are being considered in Bangladesh and the Philippines.
The Cartagena Protocol obliges the regulators in each country to consider all possible risks, and to take no account of any possible benefits. Because the anti-gmo-activists' initial concerns were principally about the environment, the responsibility for governments' regulation for GMO crops – even for Golden Rice, a public health project delivered through agriculture – usually rests with the Ministry of the Environment, not the Ministry of Health or the Ministry of Agriculture.
Activists discovered, before Golden Rice was created, that inducing fear of GMO food crops from 'multinational agribusinesses' was very good for generating donations from a public that was largely illiterate about food technology and production. And this source of emotionally charged donations would cease if Golden Rice was proven to save sight and lives, because Golden Rice represented the opposite of all the tropes used in anti-GMO campaigns.
Golden Rice is created to deliver a consumer benefit, it is not for profit – to multinational agribusiness or anyone else; the technology originated in the public sector and is being delivered through the public sector. It is entirely altruistic in its motivations; which activists find impossible to accept. So, the activists believed, suspicion against Golden Rice had to be amplified, Golden Rice had to be stopped: "If we lose the Golden Rice battle, we lose the GMO war."
Activism continues to this day. And any Environment Ministry, with no responsibility for public health or agriculture, and of course an interest in avoiding controversy about its regulatory decisions, is vulnerable to such activism.
The anti-GMO crop campaigns, and especially anti-Golden Rice campaigns, have been extraordinarily effective. If so much regulation by governments is required, surely there must be something to be suspicious about: 'There is no smoke without fire'. The suspicion pervades research institutions and universities, the publishers of scientific journals and The World Health Organisation, and UNICEF: even the most scientifically literate are fearful of entanglement in activist-stoked public controversy.
The equivalent of 13 jumbo jets full of children crashes into the ground every day and kills them all, because of VAD. Yet the solution of Golden Rice, developed by national scientists in the counties where VAD is endemic, is ignored because of fear of controversy, and because poor children's deaths can be ignored without controversy.
Perhaps more controversy lies in not taking scientifically based regulatory decisions than in taking them.
The tide is turning, however. 151 Nobel Laureates, a very significant proportion of all Nobel Laureates, have called on the UN, governments of the world, and Greenpeace to cease their unfounded vilification of GMO crops in general and Golden Rice in particular. A recent Golden Rice article commented, "What shocks me is that some activists continue to misrepresent the truth about the rice. The cynic in me expects profit-driven multinationals to behave unethically, but I want to think that those voluntarily campaigning on issues they care about have higher standards."
The recently published book has exposed the frustrating saga in simple detail. And the publicity from all the above is perhaps starting to change the balance of where controversy lies. Perhaps more controversy lies in not taking scientifically based regulatory decisions than in taking them.
But until they are taken, while there continues a chance of frustrating the objectives of the Golden Rice project, the antagonism will continue. And despite a solution so close at hand, VAD-induced death and blindness, and the misery of affected families, will continue also.
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