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."
How Excessive Regulation Helped Ignite COVID-19's Rampant Spread
Screenshot of an interactive map of coronavirus cases across the United States, current as of 1:45 p.m. Pacific time on Tuesday, March 31st. Full map accessible at https://coronavirus.jhu.edu/map.html
When historians of the future look back at the 2020 pandemic, the heroic work of Helen Y. Chu, a flu researcher at the University of Washington, will be worthy of recognition.
Chu's team bravely defied the order and conducted the testing anyway.
In late January, Chu was testing nasal swabs for the Seattle Flu Study to monitor influenza spread when she learned of the first case of COVID-19 in Washington state. She deemed it a pressing public health matter to document if and how the illness was spreading locally, so that early containment efforts could succeed. So she sought regulatory approval to adapt the Flu Study to test for the coronavirus, but the federal government denied the request because the original project was funded to study only influenza.
Aware of the urgency, Chu's team bravely defied the order and conducted the testing anyway. Soon they identified a local case in a teenager without any travel history, followed by others. Still, the government tried to shutter their efforts until the outbreak grew dangerous enough to command attention.
Needless testing delays, prompted by excessive regulatory interference, eliminated any chances of curbing the pandemic at its initial stages. Even after Chu went out on a limb to sound alarms, a heavy-handed bureaucracy crushed the nation's ability to roll out early and widespread testing across the country. The Centers for Disease Control and Prevention infamously blundered its own test, while also impeding state and private labs from coming on board, fueling a massive shortage.
The long holdup created "a backlog of testing that needed to be done," says Amesh Adalja, an infectious disease specialist who is a senior scholar at the Johns Hopkins University Center for Health Security.
In a public health crisis, "the ideal situation" would allow the government's test to be "supplanted by private laboratories" without such "a lag in that transition," Adalja says. Only after the eventual release of CDC's test could private industry "begin in earnest" to develop its own versions under the Food and Drug Administration's emergency use authorization.
In a statement, CDC acknowledged that "this process has not gone as smoothly as we would have liked, but there is currently no backlog for testing at CDC."
Now, universities and corporations are in a race against time, playing catch up as the virus continues its relentless spread, also afflicting many health care workers on the front lines.
"Home-testing accessibility is key to preventing further spread of the COVID-19 pandemic."
Hospitals are attempting to add the novel coronavirus to the testing panel of their existent diagnostic machines, which would reduce the results processing time from 48 hours to as little as four hours. Meanwhile, at least four companies announced plans to deliver at-home collection tests to help meet the demand – before a startling injunction by the FDA halted their plans.
Everlywell, an Austin, Texas-based digital health company, had been set to launch online sales of at-home collection kits directly to consumers last week. Scaling up in a matter of days to an initial supply of 30,000 tests, Everlywell collaborated with multiple laboratories where consumers could ship their nasal swab samples overnight, projecting capacity to screen a quarter-million individuals on a weekly basis, says Frank Ong, chief medical and scientific officer.
Secure digital results would have been available online within 48 hours of a sample's arrival at the lab, as well as a telehealth consultation with an independent, board-certified doctor if someone tested positive, for an inclusive $135 cost. The test has a less than 3 percent false-negative rate, Ong says, and in the event of an inadequate self-swab, the lab would not report a conclusive finding. "Home-testing accessibility," he says, "is key to preventing further spread of the COVID-19 pandemic."
But on March 20, the FDA announced restrictions on home collection tests due to concerns about accuracy. The agency did note "the public health value in expanding the availability of COVID-19 testing through safe and accurate tests that may include home collection," while adding that "we are actively working with test developers in this space."
After the restrictions were announced, Everlywell decided to allocate its initial supply of COVID-19 collection kits to hospitals, clinics, nursing homes, and other qualifying health care companies that can commit to no-cost screening of frontline workers and high-risk symptomatic patients. For now, no consumers can order a home-collection test.
"Losing two months is close to disastrous, and that's what we did."
Currently, the U.S. has ramped up to testing an estimated 100,000 people a day, according to Stat News. But 150,000 or more Americans should be tested every day, says Ashish Jha, professor and director of the Harvard Global Health Institute. Due to the dearth of tests, many sick people who suspect they are infected still cannot get confirmation unless they need to be hospitalized.
To give a concrete sense of how far behind we are in testing, consider Palm Beach County, Fla. The state's only drive-thru test center just opened there, requiring an appointment. The center aims to test 750 people per day, but more than 330,000 people have already called to try to book a slot.
"This is such a rapidly moving infection that losing a few days is bad, and losing a couple of weeks is terrible," says Jha, a practicing general internist. "Losing two months is close to disastrous, and that's what we did."
At this point, it will take a long time to fully ramp up. "We are blindfolded," he adds, "and I'd like to take the blindfolds off so we can fight this battle with our eyes wide open."
Better late than never: Yesterday, FDA Commissioner Stephen Hahn said in a statement that the agency has worked with more than 230 test developers and has approved 20 tests since January. An especially notable one was authorized last Friday – 67 days since the country's first known case in Washington state. It's a rapid point-of-care test from medical-device firm Abbott that provides positive results in five minutes and negative results in 13 minutes. Abbott will send 50,000 tests a day to urgent care settings. The first tests are expected to ship tomorrow.
Your Privacy vs. the Public's Health: High-Tech Tracking to Fight COVID-19 Evokes Orwell
Governments around the world are using technology to track their citizens to contain COVID-19.
The COVID-19 pandemic has placed public health and personal privacy on a collision course, as smartphone technology has completely rewritten the book on contact tracing.
It's not surprising that an autocratic regime like China would adopt such measures, but democracies such as Israel have taken a similar path.
The gold standard – patient interviews and detective work – had been in place for more than a century. It's been all but replaced by GPS data in smartphones, which allows contact tracing to occur not only virtually in real time, but with vastly more precision.
China has gone the furthest in using such tech to monitor and prevent the spread of the coronavirus. It developed an app called Health Code to determine which of its citizens are infected or at risk of becoming infected. It has assigned each individual a color code – red, yellow or green – and restricts their movement depending on their assignment. It has also leveraged its millions of public video cameras in conjunction with facial recognition tech to identify people in public who are not wearing masks.
It's not surprising that an autocratic regime like China would adopt such measures, but democracies such as Israel have taken a similar path. The national security agency Shin Bet this week began analyzing all personal cellphone data under emergency measures approved by the government. It texts individuals when it's determined they had been in contact with someone who had the coronavirus. In Spain and China, police have sent drones aloft searching for people violating stay-at-home orders. Commands to disperse can be issued through audio systems built into the aircraft. In the U.S., efforts are underway to lift federal restrictions on drones so that police can use them to prevent people from gathering.
The chief executive of a drone manufacturer in the U.S. aptly summed up the situation in an interview with the Financial Times: "It seems a little Orwellian, but this could save lives."
Epidemics and how they're surveilled often pose thorny dilemmas, according to Craig Klugman, a bioethicist and professor of health sciences at DePaul University in Chicago. "There's always a moral issue to contact tracing," he said, adding that the issue doesn't change by nation, only in the way it's resolved.
"Once certain privacy barriers have been breached, it can be difficult to roll them back again."
In China, there's little to no expectation for privacy, so their decision to take the most extreme measures makes sense to Klugman. "In China, the community comes first. In the U.S., individual rights come first," he said.
As the U.S. has scrambled to develop testing kits and manufacture ventilators to identify potential patients and treat them, individual rights have mostly not received any scrutiny. However, that could change in the coming weeks.
The American approach is also leaning toward using smartphone apps, but in a way that may preserve the privacy of users. Researchers at MIT have released a prototype known as Private Kit: Safe Paths. Patients diagnosed with the coronavirus can use the app to disclose their location trail for the prior 28 days to other users without releasing their specific identity. They also have the option of sharing the data with public health officials. But such an app would only be effective if there is a significant number of users.
Singapore is offering a similar app to its citizens known as TraceTogether, which uses both GPS and Bluetooth pings among users to trace potential encounters. It's being offered on a voluntary basis.
The Electronic Frontier Foundation, the leading nonprofit organization defending civil liberties in the digital world, said it is monitoring how these apps are developed and deployed. "Governments around the world are demanding new dragnet location surveillance powers to contain the COVID-19 outbreak," it said in a statement. "But before the public allows their governments to implement such systems, governments must explain to the public how these systems would be effective in stopping the spread of COVID-19. There's no questioning the need for far-reaching public health measures to meet this urgent challenge, but those measures must be scientifically rigorous, and based on the expertise of public health professionals."
Andrew Geronimo, director of the intellectual property venture clinic at the Case Western University School of Law, said that the U.S. government is currently in talks with Facebook, Google and other tech companies about using deidentified location data from smartphones to better monitor the progress of the outbreak. He was hesitant to endorse such a step.
"These companies may say that all of this data is anonymized," he said, "but studies have shown that it is difficult to fully anonymize data sets that contain so much information about us."
Beyond the technical issues, social attitudes may mount another challenge. Epic events such as 9/11 tend to loosen vigilance toward protecting privacy, according to Klugman and Geronimo. And as more people are sickened and hospitalized in the U.S. with COVID-19, Klugman believes more Americans will be willing to allow themselves to be tracked. "If that happens, there needs to be a time limitation," he said.
However, even if time limits are put in place, Geronimo believes it would lead to an even greater rollback of privacy during the next crisis.
"Once certain privacy barriers have been breached, it can be difficult to roll them back again," he warned. "And the prior incidents could always be used as a precedent – or as proof of concept."