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."
“Disinfection Tunnels” Are Popping Up Around the World, Fueled By Misinformation and Fear
A screenshot of a video published by The Guardian of a tunnel used in a Mexican border town to "disinfect" U.S. visitors in an attempt to prevent them from spreading the coronavirus.
In an incident that sparked widespread outrage across India in late March, officials in the north Indian state of Uttar Pradesh sprayed hundreds of migrant workers, including women and children, with a chemical solution to sanitize them, in a misguided attempt to contain the spread of the novel coronavirus.
Since COVID-19 is a respiratory disorder, disinfecting a person's body or clothes cannot protect them from contracting the novel coronavirus, or help in containing the pathogen's spread.
Health officials reportedly doused the group with a diluted mixture of sodium hypochlorite – a bleaching agent harmful to humans, which led to complaints of skin rashes and eye irritation. The opposition termed the instance 'inhuman', compelling the state government to order an investigation into the mass 'chemical bath.'
"I don't think the officials thought this through," says Thomas Abraham, a professor with The University of Hong Kong, and a former consultant for the World Health Organisation (WHO) on risk communication. "Spraying people with bleach can prove to be harmful, and there is no guideline … that recommends it. This was some sort of a kneejerk reaction."
Although spraying individuals with chemicals led to a furor in the South Asian nation owing to its potential dangers, so-called "disinfection tunnels" have sprung up in crowded public places around the world, including malls, offices, airports, railway stations and markets. Touted as mass disinfectants, these tunnels spray individuals with chemical disinfectant liquids, mists or fumes through nozzles for a few seconds, purportedly to sanitize them -- though experts strongly condemn their use. The tunnels have appeared in at least 16 countries: India, Malaysia, Scotland, Albania, Argentina, Colombia, Singapore, China, Pakistan, France, Vietnam, Bosnia and Herzegovina, Chile, Mexico, Sri Lanka and Indonesia. Russian President Vladimir Putin even reportedly has his own tunnel at his residence.
While U.S. visitors to Mexico are "disinfected" through these sanitizing tunnels, there is no evidence that the mechanism is currently in use within the United States. However, the situation could rapidly change with international innovators like RD Pack, an Israeli start-up, pushing for their deployment. Many American and multinational companies like Stretch Structures, Guilio Barbieri and Inflatable Design Works are also producing these systems. As countries gradually ease lockdown restrictions, their demand is on the rise -- despite a stringent warning from the WHO against their potential health hazards.
"Spraying individuals with disinfectants (such as in a tunnel, cabinet, or chamber) is not recommended under any circumstances," the WHO warned in a report on May 15. "This could be physically and psychologically harmful and would not reduce an infected person's ability to spread the virus through droplets or contact. Moreover, spraying individuals with chlorine and other toxic chemicals could result in eye and skin irritation, bronchospasm due to inhalation, and gastrointestinal effects such as nausea and vomiting."
Disinfection tunnels largely spray a diluted mixture of sodium hypochlorite, a chlorine compound commonly known as bleach, often used to disinfect inanimate surfaces. Known for its hazardous properties, the WHO, in a separate advisory on COVID-19, warns that spraying bleach or any other disinfectant on individuals can prove to be poisonous if ingested, and that such substances should be used only to disinfect surfaces.
Considering the effect of sodium hypochlorite on mucous membranes, the European Centre for Disease Prevention and Control, an EU agency focussed on infectious diseases, recommends limited use of the chemical compound even when disinfecting surfaces – only 0.05 percent for cleaning surfaces, and 0.1 percent for toilets and bathroom sinks. The Indian health ministry also cautioned against spraying sodium hypochlorite recently, stating that its inhalation can lead to irritation of mucous membranes of the nose, throat, and respiratory tract.
In addition to the health hazards that such sterilizing systems pose, they have little utility, argues Indian virologist T. Jacob John. Since COVID-19 is a respiratory disorder, disinfecting a person's body or clothes cannot protect them from contracting the novel coronavirus, or help in containing the pathogen's spread.
"It's a respiratory infection, which means that you have the virus in your respiratory tract, and of course, that shows in your throat, therefore saliva, etc.," says John. "The virus does not survive outside the body for a long time, unless it is in freezing temperatures. Disinfecting a person's clothes or their body makes no sense."
Disinfection tunnels have limited, if any, impact on the main modes of coronavirus transmission, adds Craig Janes, director, School of Public Health and Health Systems at Canada's University of Waterloo. He explains that the nature of COVID-19 transmission is primarily from person-to-person, either directly, or via an object that is shared between two individuals. Measures like physical distancing and handwashing take care of these transmission risks.
"My view of these kinds of actions are that they are principally symbolic, indicating to a concerned population that 'something is being done,' to martial support for government or health system efforts," says Janes. "So perhaps a psychological benefit, but I'm not sure that this benefit would outweigh the risks."
"They may make people feel that their risk of infection has been reduced, and also that they do not have to worry about infecting others."
A recent report by Health Care Without Harm (HCWH), an international not-for-profit organization focused on sustainable health care around the world, states that disinfection tunnels have little evidence to demonstrate their efficacy or safety.
"If the goal is to reduce the spread of the virus by decontaminating the exterior clothing, shoes, and skin of the general public, there is no evidence that clothes are an important vector for transmission. If the goal is to attack the virus in the airways, what is the evidence that a 20-30 second external application is efficacious and safe?" the report questions. "The World Health Organization recommends more direct and effective ways to address hand hygiene, with interventions known to be effective."
If an infected person walks through a disinfection tunnel, he would still be infectious, as the chemicals will only disinfect the surfaces, says Gerald Keusch, a professor of medicine and international health at Boston University's Schools of Medicine and Public Health.
"While we know that viruses can be "disinfected" from surfaces and hands, disinfectants can be harmful to health if ingested or inhaled. The underlying principle of medicine is to do no harm, and we always measure benefit against risk when approving interventions. I don't know if this has been followed and assessed with respect to these devices," says Keusch. "It's a really bad idea."
Experts warn that such tunnels may also create a false sense of security, discouraging people from adopting best practice methods like handwashing, social distancing, avoiding crowded places, and using masks to combat the spread of COVID-19.
"They may make people feel that their risk of infection has been reduced, and also that they do not have to worry about infecting others," says Janes. "These are false assumptions, and may lead to increasing rather than reducing transmission."
n artist rendering of a "smart toilet" that gathers biometric data to monitor a person's health in real time.
It looks like an ordinary toilet but it is anything but. The "smart toilet" is the diagnostic tool of the future, equipped with cameras that take snapshots of the users and their waste, motion sensors to analyze what's inside the urine and stool samples, and software that automatically sends data to a secure, cloud-based system that can be easily accessed by your family doctor.
"It's a way of doing community surveillance. If there is a second wave of infections in the future, we'll know right away."
Using urine "dipstick tests" similar to the home pregnancy strips, the smart toilet can detect certain proteins, immune system biomarkers and blood cells that indicate the presence of such diseases as infections, bladder cancer, and kidney failure.
The rationale behind this invention is that some of the best ways of detecting what's going on in our bodies is by analyzing the substances we excrete every day, our sweat, urine, saliva and yes, our feces. Instead of getting sporadic snapshots from doctor's visits once or twice a year, the smart toilet provides continuous monitoring of our health 24/7, so we can catch the tell-tale molecular signature of illnesses at their earliest and most treatable stages. A brainchild of Stanford University researchers, they're now working to add a COVID-19 detection component to their suite of technologies—corona virus particles can be spotted in stool samples—and hope to have the system available within the year.
"We can connect the toilet system to cell phones so we'll know the results within 30 minutes," says Seung-min Park, a lead investigator on the research team that devised this technology and a senior research scientist at the Stanford University School of Medicine. "The beauty of this technology is that it can continuously monitor even after this pandemic is over. It's a way of doing community surveillance. If there is a second wave of infections in the future, we'll know right away."
Experts believe that the COVID-19 pandemic will accelerate the widespread acceptance of in-home diagnostic tools such as this. "Shock events" like pandemics can be catalysts for sweeping changes in society, history shows us. The Black Death marked the end of feudalism and ushered in the Renaissance while the aftershocks of the Great Depression and two world wars in the 20th century led to the social safety net of the New Deal and NATO and the European Union. COVID-19 could fundamentally alter the way we deliver healthcare, abandoning the outdated 20th century brick and mortar fee-for-service model in favor of digital medicine. At-home diagnostics may be the leading edge of this seismic shift and the pandemic could accelerate the product innovations that allow for home-based medical screening.
"That's the silver lining to this devastation," says Dr. Leslie Saxon, executive director of the USC Center for Body Computing at the Keck School of Medicine in Los Angeles. As an interventional cardiologist, Saxon has spent her career devising and refining the implantable and wearable wireless devices that are used to treat and diagnose heart conditions and prevent sudden death. "This will open up innovation—research has been stymied by a lack of imagination and marriage to an antiquated model," she adds. "There are already signs this is happening—relaxing state laws about licensure, allowing physicians to deliver health care in non-traditional ways. That's a real sea change and will completely democratize medical information and diagnostic testing."
Ironically, diagnostics have long been a step-child of modern medicine, even though accurate and timely diagnostics play a crucial role in disease prevention, detection and management. "The delivery of health care has proceeded for decades with a blind spot: diagnostic errors—inaccurate or delayed diagnoses—persist throughout all settings of care and continue to harm an unacceptable number of patients," according to a 2015 National Academy of Medicine report. That same report found as many as one out of five adverse events in the hospital result from these errors and they contribute to 10 percent of all patient deaths.
The pandemic should alter the diagnostic landscape. We already have a wealth of wearable and implantable devices, like glucose sensors to monitor blood sugar levels for diabetics, Apple's smart watch, electrocardiogram devices that can detect heart arrythmias, and heart pacemakers.
The Food and Drug Administration is working closely with in-home test developers to make accurate COVID-19 diagnostic tools readily available and has so far greenlighted three at-home collection test kits. Two, LabCorp's and Everlywell's, use nasal swabs to take samples. The third one is a spit test, using saliva samples, that was devised by a Rutgers University laboratory in partnership with Spectrum Solutions and Accurate Diagnostic Labs.
The only way to safely reopen is through large scale testing, but hospitals and doctors' offices are no longer the safest places.
In fact, DIY diagnostic company Everlywell, an Austin, Texas- based digital health company, already offers more than 30 at-home kits for everything from fertility to food sensitivity tests. Typically, consumers collect a saliva or finger-prick blood sample, dispatch it in a pre-paid shipping envelope to a laboratory, and a physician will review the results and send a report to consumers' smartphones.
Thanks to advances in technology, samples taken at home can now be preserved long enough to arrive intact at diagnostic laboratories. The key is showing the agency "transport and shipping don't change or interfere with the integrity of the samples," says Dr. Frank Ong, Everlywell's chief medical and scientific officer.
Ong is keenly aware of the importance of saturation testing because of the lessons learned by colleagues fighting the SARS pandemic in his family's native Taiwan in 2003. "In the beginning, doctors didn't know what they were dealing with and didn't protect themselves adequately," he says. "But over two years, they learned the hard way that there needs to be enough testing, contact tracing of those who have been exposed, and isolation of people who test positive. The value of at-home testing is that it can be done on the kind of broad basis that needs to happen for our country to get back to work."
Because of the pandemic, new policies have removed some of the barriers that impeded the widespread adoption of home-based diagnostics and telemedicine. Physicians can now practice across state lines, get reimbursed for telemedicine visits and use FaceTime to communicate with their patients, which had long been considered taboo because of privacy issues. Doctors and patients are becoming more comfortable and realizing the convenience and benefits of being able to do these things virtually.
Added to this, the only way to safely reopen for business without triggering a second and perhaps even more deadly wave of sickness is through large-scale testing, but hospitals and doctors' offices are no longer the safest places. "We don't want people sitting in a waiting room who later find out they're positive, and potentially infected everyone, including doctors and nurses," says Dr. Kavita Patel, a physician in Washington, DC who served as a policy director in the Obama White House.
In-home testing avoids the risks of direct exposure to the virus for both patients and health care professionals, who can dispense with cumbersome protective gear to take samples, and also enables people without reliable transportation or child-care to learn their status. "At home testing can be a critical component of our country's overall testing strategy," says Dr. Shantanu Nundy, chief medical officer at Accolade Health and on the faculty of the Milken Institute School of Public Health at George Washington University. "Once we're back at work, we need to be much more targeted, and have much more access to data and controlling those outbreaks as tightly as possible. The best way to do that is by leapfrogging clinics and being able to deliver tests at home for people who are disenfranchised by the current system."
In the not-too-distant future, in-home diagnostics could be a key component of precision medicine, which is customized care tailored specifically to each patient's individual needs. Like Stanford's smart toilet prototype, these ongoing surveillance tools will gather health data, ranging from exposures to toxins and pollutions in the environment to biochemical activity, like rising blood pressure, signs of inflammation, failing kidneys or tiny cancerous tumors, and provide continuous real-time information.
"These can be deeply personalized and enabled by smart phones, sensors and artificial intelligence," says USC's Leslie Saxon. "We'll be seeing the floodgates opening to patients accessing medical services through the same devices that they access other things, and leveraging these tools for our health and to fine tune disease management in a model of care that is digitally enabled."
[Editor's Note: This article was originally published on June 8th, 2020 as part of a standalone magazine called GOOD10: The Pandemic Issue. Produced as a partnership among LeapsMag, The Aspen Institute, and GOOD, the magazine is available for free online.]