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."
Why you should (virtually) care
As the pandemic turns endemic, healthcare providers have been eagerly urging patients to return to their offices to enjoy the benefits of in-person care.
But wait.
The last two years have forced all sorts of organizations to be nimble, adaptable and creative in how they work, and this includes healthcare providers’ efforts to maintain continuity of care under the most challenging of conditions. So before we go back to “business as usual,” don’t we owe it to those providers and ourselves to admit that business as usual did not work for most of the people the industry exists to help? If we’re going to embrace yet another period of change – periods that don’t happen often in our complex industry – shouldn’t we first stop and ask ourselves what we’re trying to achieve?
Certainly, COVID has shown that telehealth can be an invaluable tool, particularly for patients in rural and underserved communities that lack access to specialty care. It’s also become clear that many – though not all – healthcare encounters can be effectively conducted from afar. That said, the telehealth tactics that filled the gap during the pandemic were largely stitched together substitutes for existing visit-based workflows: with offices closed, patients scheduled video visits for help managing the side effects of their blood pressure medications or to see their endocrinologist for a quarterly check-in. Anyone whose children slogged through the last year or two of remote learning can tell you that simply virtualizing existing processes doesn’t necessarily improve the experience or the outcomes!
But what if our approach to post-pandemic healthcare came from a patient-driven perspective? We have a fleeting opportunity to advance a care model centered on convenient and equitable access that first prioritizes good outcomes, then selects approaches to care – and locations – tailored to each patient. Using the example of education, imagine how effective it would be if each student, regardless of their school district and aptitude, received such individualized attention.
That’s the idea behind virtual-first care (V1C), a new care model centered on convenient, customized, high-quality care that integrates a full suite of services tailored directly to patients’ clinical needs and preferences. This package includes asynchronous communication such as texting; video and other live virtual modes; and in-person options.
V1C goes beyond what you might think of as standard “telehealth” by using evidence-based protocols and tools that include traditional and digital therapeutics and testing, personalized care plans, dynamic patient monitoring, and team-based approaches to care. This could include spit kits mailed for laboratory tests and complementing clinical care with health coaching. V1C also replaces some in-person exams with ongoing monitoring, using sensors for more ‘whole person’ care.
Amidst all this momentum, we have the opportunity to rethink the goals of healthcare innovation, but that means bringing together key stakeholders to demonstrate that sustainable V1C can redefine healthcare.
Established V1C healthcare providers such as Omada, Headspace, and Heartbeat Health, as well as emerging market entrants like Oshi, Visana, and Wellinks, work with a variety of patients who have complicated long-term conditions such as diabetes, heart failure, gastrointestinal illness, endometriosis, and COPD. V1C is comprehensive in ways that are lacking in digital health and its other predecessors: it has the potential to integrate multiple data streams, incorporate more frequent touches and check-ins over time, and manage a much wider range of chronic health conditions, improving lives and reducing disease burden now and in the future.
Recognizing the pandemic-driven interest in virtual care, significant energy and resources are already flowing fast toward V1C. Some of the world’s largest innovators jumped into V1C early on: Verily, Alphabet’s Life Sciences Company, launched Onduo in 2016 to disrupt the diabetes healthcare market, and is now well positioned to scale its solutions. Major insurers like Aetna and United now offer virtual-first plans to members, responding as organizations expand virtual options for employees. Amidst all this momentum, we have the opportunity to rethink the goals of healthcare innovation, but that means bringing together key stakeholders to demonstrate that sustainable V1C can redefine healthcare.
That was the immediate impetus for IMPACT, a consortium of V1C companies, investors, payers and patients founded last year to ensure access to high-quality, evidence-based V1C. Developed by our team at the Digital Medicine Society (DiMe) in collaboration with the American Telemedicine Association (ATA), IMPACT has begun to explore key issues that include giving patients more integrated experiences when accessing both virtual and brick-and-mortar care.
Digital Medicine Society
V1C is not, nor should it be, virtual-only care. In this new era of hybrid healthcare, success will be defined by how well providers help patients navigate the transitions. How do we smoothly hand a patient off from an onsite primary care physician to, say, a virtual cardiologist? How do we get information from a brick-and-mortar to a digital portal? How do you manage dataflow while still staying HIPAA compliant? There are many complex regulatory implications for these new models, as well as an evolving landscape in terms of privacy, security and interoperability. It will be no small task for groups like IMPACT to determine the best path forward.
None of these factors matter unless the industry can recruit and retain clinicians. Our field is facing an unprecedented workforce crisis. Traditional healthcare is making clinicians miserable, and COVID has only accelerated the trend of overworked, disenchanted healthcare workers leaving in droves. Clinicians want more interactions with patients, and fewer with computer screens – call it “More face time, less FaceTime.” No new model will succeed unless the industry can more efficiently deploy its talent – arguably its most scarce and precious resource. V1C can help with alleviating the increasing burden and frustration borne by individual physicians in today’s status quo.
In healthcare, new technological approaches inevitably provoke no shortage of skepticism. Past lessons from Silicon Valley-driven fixes have led to understandable cynicism. But V1C is a different breed of animal. By building healthcare around the patient, not the clinic, V1C can make healthcare work better for patients, payers and providers. We’re at a fork in the road: we can revert back to a broken sick-care system, or dig in and do the hard work of figuring out how this future-forward healthcare system gets financed, organized and executed. As a field, we must find the courage and summon the energy to embrace this moment, and make it a moment of change.
Podcast: The future of brain health with Percy Griffin
Today's guest is Percy Griffin, director of scientific engagement for the Alzheimer’s Association, a nonprofit that’s focused on speeding up research, finding better ways to detect Alzheimer’s earlier and other approaches for reducing risk. Percy has a doctorate in molecular cell biology from Washington University, he’s led important research on Alzheimer’s, and you can find the link to his full bio in the show notes, below.
Our topic for this conversation is the present and future of the fight against dementia. Billions of dollars have been spent by the National Institutes of Health and biotechs to research new treatments for Alzheimer's and other forms of dementia, but so far there's been little to show for it. Last year, Aduhelm became the first drug to be approved by the FDA for Alzheimer’s in 20 years, but it's received a raft of bad publicity, with red flags about its effectiveness, side effects and cost.
Meanwhile, 6.5 million Americans have Alzheimer's, and this number could increase to 13 million in 2050. Listen to this conversation if you’re concerned about your own brain health, that of family members getting older, or if you’re just concerned about the future of this country with experts predicting the number people over 65 will increase dramatically in the very near future.
Listen to the Episode
Listen on Apple | Listen on Spotify | Listen on Stitcher | Listen on Amazon | Listen on Google
4:40 - We talk about the parts of Percy’s life that led to him to concentrate on working in this important area.
6:20 - He defines Alzheimer's and dementia, and discusses the key elements of communicating science.
10:20 - Percy explains why the Alzheimer’s Association has been supportive of Aduhelm, even as others have been critical.
17:58 - We talk about therapeutics under development, which ones to be excited about, and how they could be tailored to a person's own biology.
24:25 - Percy discusses funding and tradeoffs between investing more money into Alzheimer’s research compared to other intractable diseases like cancer, and new opportunities to accelerate progress, such as ARPA-H, President Biden’s proposed agency to speed up health breakthroughs.
27:24 - We talk about the social determinants of brain health. What are the pros/cons of continuing to spend massive sums of money to develop new drugs like Aduhelm versus refocusing on expanding policies to address social determinants - like better education, nutritious food and safe drinking water - that have enabled some groups more than others to enjoy improved cognition late in life.
34:18 - Percy describes his top lifestyle recommendations for protecting your mind.
37:33 - Is napping bad for the brain?
39:39 - Circadian rhythm and Alzheimer's.
42:34 - What tests can people take to check their brain health today, and which biomarkers are we making progress on?
47:25 - Percy highlights important programs run by the Alzheimer’s Association to support advances.
Show links:
** After this episode was recorded, the Centers for Medicare and Medicaid Services affirmed its decision from last June to limit coverage of Aduhelm. More here.
- Percy Griffin's bio: https://www.alz.org/manh/events/alztalks/upcoming-...
- The Alzheimer's Association's Part the Cloud program: https://alz.org/partthecloud/about-us.asp
- The paradox of dementia rates decreasing: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7455342/
- The argument for focusing more resources on improving institutions and social processes for brain health: https://www.statnews.com/2021/09/23/the-brain-heal...
- Recent research on napping: https://www.ocregister.com/2022/03/25/alzheimers-s...
- The Alzheimer's Association helpline: https://www.alz.org/help-support/resources/helpline
- ALZConnected, a free online community for people affected by dementia https://www.alzconnected.org/
- TrialMatch for people with dementia and healthy volunteers to find clinical trials for Alzheimer's and other dementia: https://www.alz.org/alzheimers-dementia/research_p...