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."
As countries around the world combat the coronavirus outbreak, governments that already operated sophisticated surveillance programs are ramping up the tracking of their citizens.
"The potential for invasions of privacy, abuse, and stigmatization is enormous."
Countries like China, South Korea, Israel, Singapore and others are closely monitoring citizens to track the spread of the virus and prevent further infections, and policymakers in the United States have proposed similar steps. These shifts in policy have civil liberties defenders alarmed, as history has shown increases in surveillance tend to stick around after an emergency is over.
In China, where the virus originated and surveillance is already ubiquitous, the government has taken measures like having people scan a QR code and answer questions about their health and travel history to enter their apartment building. The country has also increased the tracking of cell phones, encouraged citizens to report people who appear to be sick, utilized surveillance drones, and developed facial recognition that can identify someone even if they're wearing a mask.
In Israel, the government has begun tracking people's cell phones without a court order under a program that was initially meant to counter terrorism. Singapore has also been closely tracking people's movements using cell phone data. In South Korea, the government has been monitoring citizens' credit card and cell phone data and has heavily utilized facial recognition to combat the spread of the coronavirus.
Here at home, the United States government and state governments have been using cell phone data to determine where people are congregating. White House senior adviser Jared Kushner's task force to combat the coronavirus outbreak has proposed using cell phone data to track coronavirus patients. Cities around the nation are also using surveillance drones to maintain social distancing orders. Companies like Apple and Google that work closely with the federal government are currently developing systems to track Americans' cell phones.
All of this might sound acceptable if you're worried about containing the outbreak and getting back to normal life, but as we saw when the Patriot Act was passed in 2001 in the wake of the 9/11 terrorist attacks, expansions of the surveillance state can persist long after the emergency that seemed to justify them.
Jay Stanley, senior policy analyst with the ACLU Speech, Privacy, and Technology Project, says that this public health emergency requires bold action, but he worries that actions may be taken that will infringe on our privacy rights.
"This is an extraordinary crisis that justifies things that would not be justified in ordinary times, but we, of course, worry that any such things would be made permanent," Stanley says.
Stanley notes that the 9/11 situation was different from this current situation because we still face the threat of terrorism today, and we always will. The Patriot Act was a response to that threat, even if it was an extreme response. With this pandemic, it's quite possible we won't face something like this again for some time.
"We know that for the last seven or eight decades, we haven't seen a microbe this dangerous become a pandemic, and it's reasonable to expect it's not going to be happening for a while afterward," Stanley says. "We do know that when a vaccine is produced and is produced widely enough, the COVID crisis will be over. This does, unlike 9/11, have a definitive ending."
The ACLU released a white paper last week outlining the problems with using location data from cell phones and how policymakers should proceed when they discuss the usage of surveillance to combat the outbreak.
"Location data contains an enormously invasive and personal set of information about each of us, with the potential to reveal such things as people's social, sexual, religious, and political associations," they wrote. "The potential for invasions of privacy, abuse, and stigmatization is enormous. Any uses of such data should be temporary, restricted to public health agencies and purposes, and should make the greatest possible use of available techniques that allow for privacy and anonymity to be protected, even as the data is used."
"The first thing you need to combat pervasive surveillance is to know that it's occurring."
Sara Collins, policy counsel at the digital rights organization Public Knowledge, says that one of the problems with the current administration is that there's not much transparency, so she worries surveillance could be increased without the public realizing it.
"You'll often see the White House come out with something—that they're going to take this action or an agency just says they're going to take this action—and there's no congressional authorization," Collins says. "There's no regulation. There's nothing there for the public discourse."
Collins says it's almost impossible to protect against infringements on people's privacy rights if you don't actually know what kind of surveillance is being done and at what scale.
"I think that's very concerning when there's no accountability and no way to understand what's actually happening," Collins says. "The first thing you need to combat pervasive surveillance is to know that it's occurring."
We should also be worried about corporate surveillance, Collins says, because the tech companies that keep track of our data work closely with the government and do not have a good track record when it comes to protecting people's privacy. She suspects these companies could use the coronavirus outbreak to defend the kind of data collection they've been engaging in for years.
Collins stresses that any increase in surveillance should be transparent and short-lived, and that there should be a limit on how long people's data can be kept. Otherwise, she says, we're risking an indefinite infringement on privacy rights. Her organization will be keeping tabs as the crisis progresses.
It's not that we shouldn't avail ourselves of modern technology to fight the pandemic. Indeed, once lockdown restrictions are gradually lifted, public health officials must increase their ability to isolate new cases and trace, test, and quarantine contacts.
But tracking the entire populace "Big Brother"-style is not the ideal way out of the crisis. Last week, for instance, a group of policy experts -- including former FDA Commissioner Scott Gottlieb -- published recommendations for how to achieve containment. They emphasized the need for widespread diagnostic and serologic testing as well as rapid case-based interventions, among other measures -- and they, too, were wary of pervasive measures to follow citizens.
The group wrote: "Improved capacity [for timely contact tracing] will be most effective if coordinated with health care providers, health systems, and health plans and supported by timely electronic data sharing. Cell phone-based apps recording proximity events between individuals are unlikely to have adequate discriminating ability or adoption to achieve public health utility, while introducing serious privacy, security, and logistical concerns."
The bottom line: Any broad increases in surveillance should be carefully considered before we go along with them out of fear. The Founders knew that privacy is integral to freedom; that's why they wrote the Fourth Amendment to protect it, and that right shouldn't be thrown away because we're in an emergency. Once you lose a right, you don't tend to get it back.
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.