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."
The Promise of Pills That Know When You Swallow Them
Dr. Sara Browne, an associate professor of clinical medicine at the University of California, San Diego, is a specialist in infectious diseases and, less formally, "a global health person." She often travels to southern Africa to meet with colleagues working on the twin epidemics of HIV and tuberculosis.
"This technology, in my opinion, is an absolute slam dunk for tuberculosis."
Lately she has asked them to name the most pressing things she can help with as a researcher based in a wealthier country. "Over and over and over again," she says, "the only thing they wanted to know is whether their patients are taking the drugs."
Tuberculosis is one of world's deadliest diseases; every year there are 10 million new infections and more than a million deaths. When a patient with tuberculosis is prescribed medicine to combat the disease, adherence to the regimen is important not just for the individual's health, but also for the health of the community. Poor adherence can lead to lengthier and more costly treatment and, perhaps more importantly, to drug-resistant strains of the disease -- an increasing global threat.
Browne is testing a new method to help healthcare workers track their patients' adherence with greater precision—close to exact precision even. They're called digital pills, and they involve a patient swallowing medicine as they normally would, only the capsule contains a sensor that—when it contacts stomach acid—transmits a signal to a small device worn on or near the body. That device in turn sends a signal to the patient's phone or tablet and into a cloud-based database. The fact that the pill has been swallowed has therefore been recorded almost in real time, and notice is available to whoever has access to the database.
"This technology, in my opinion, is an absolute slam dunk for tuberculosis," Browne says. TB is much more prevalent in poorer regions of the world—in Sub-Saharan Africa, for example—than in richer places like the U.S., where Browne's studies thus far have taken place. But when someone is diagnosed in the U.S., because of the risk to others if it spreads, they will likely have to deal with "directly observed therapy" to ensure that they take their medicines correctly.
DOT, as it's called, requires the patient to meet with a healthcare worker several days a week, or every day, so that the medicine intake can be observed in person -- an expensive and time-consuming process. Still, the Centers for Disease Control and Prevention website says (emphasis theirs), "DOT should be used for ALL patients with TB disease, including children and adolescents. There is no way to accurately predict whether a patient will adhere to treatment without this assistance."
Digital pills can help with both the cost and time involved, and potentially improve adherence in places where DOT is impossibly expensive. With the sensors, you can monitor a patient's adherence without a healthcare worker physically being in the room. Patients can live their normal lives and if they miss a pill, they can receive a reminder by text or a phone call from the clinic or hospital. "They can get on with their lives," said Browne. "They don't need the healthcare system to interrupt them."
A 56-year-old patient who participated in one of Browne's studies when he was undergoing TB treatment says that before he started taking the digital pills, he would go to the clinic at least once every day, except weekends. Once he switched to digital pills, he could go to work and spend time with his wife and children instead of fighting traffic every day to get to the clinic. He just had to wear a small patch on his abdomen, which would send the signal to a tablet provided by Browne's team. When he returned from work, he could see the results—that he'd taken the pill—in a database accessed via the tablet. (He could also see his heart rate and respiratory rate.) "I could do my daily activities without interference," he said.
Dr. Peter Chai, a medical toxicologist and emergency medicine physician at Brigham and Women's Hospital in Boston, is studying digital pills in a slightly different context, to help fight the country's opioid overdose crisis. Doctors like Chai prescribe pain medicine, he says, but then immediately put the onus on the patient to decide when to take it. This lack of guidance can lead to abuse and addiction. Patients are often told to take the meds "as needed." Chai and his colleagues wondered, "What does that mean to patients? And are people taking more than they actually need? Because pain is such a subjective experience."
The patients "liked the fact that somebody was watching them."
They wanted to see what "take as needed" actually led to, so they designed a study with patients who had broken a bone and come to the hospital's emergency department to get it fixed. Those who were prescribed oxycodone—a pharmaceutical opioid for pain relief—got enough digital pills to last one week. They were supposed to take the pills as needed, or as many as three pills per day. When the pills were ingested, the sensor sent a signal to a card worn on a lanyard around the neck.
Chai and his colleagues were able to see exactly when the patients took the pills and how many, and to detect patterns of ingestion more precisely than ever before. They talked to the patients after the seven days were up, and Chai said most were happy to be taking digital pills. The patients saw it as a layer of protection from afar. "They liked the fact that somebody was watching them," Chai said.
Both doctors, Browne and Chai, are in early stages of studies with patients taking pre-exposure prophylaxis, medicines that can protect people with a high-risk of contracting HIV, such as injectable drug users. Without good adherence, patients leave themselves open to getting the virus. If a patient is supposed to take a pill at 2 p.m. but the digital pill sensor isn't triggered, the healthcare provider can have an automatic message sent as a reminder. Or a reminder to one of the patient's friends or loved ones.
"Like Swallowing Your Phone"?
Deven Desai, an associate professor of law and ethics at Georgia Tech, says that digital pills sound like a great idea for helping with patient adherence, a big issue that self-reporting doesn't fully solve. He likes the idea of a physician you trust having better information about whether you're taking your medication on time. "On the surface that's just cool," he says. "That's a good thing." But Desai, who formerly worked as academic research counsel at Google, said that some of the same questions that have come up in recent years with social media and the Internet in general also apply to digital pills.
"Think of it like your phone, but you swallowed it," he says. "At first it could be great, simple, very much about the user—in this case, the patient—and the data is going between you and your doctor and the medical people it ought to be going to. Wonderful. But over time, phones change. They become 'smarter.'" And when phones and other technologies become smarter, he says, the companies behind them tend to expand the type of data they collect, because they can. Desai says it will be crucial that prescribers be completely transparent about who is getting the patients' data and for what purpose.
"We're putting stuff in our body in good faith with our medical providers, and what if it turned out later that all of a sudden someone was data mining or putting in location trackers and we never knew about that?" Desai asks. "What science has to realize is if they don't start thinking about this, what could be a wonderful technology will get killed."
Leigh Turner, an associate professor at the University of Minnesota's Center for Bioethics, agrees with Desai that digital pills have great promise, and also that there are clear reasons to be concerned about their use. Turner compared the pills to credit cards and social media, in that the data from them can potentially be stolen or leaked. One question he would want answered before the pills were normalized: "What kind of protective measures are in place to make sure that personal information isn't spilling out and being acquired by others or used by others in unexpected and unwanted ways?"
If digital pills catch on, some experts worry that they may one day not be a voluntary technology.
Turner also wonders who will have access to the pills themselves. Only those who can afford both the medicine plus the smartphones that are currently required for their use? Or will people from all economic classes have access? If digital pills catch on, he also worries they may one day not be a voluntary technology.
"When it comes to digital pills, it's not something that's really being foisted on individuals. It's more something that people can be informed of and can choose to take or not to take," he says. "But down the road, I can imagine a scenario where we move away from purely voluntary agreements to it becoming more of an expectation."
He says it's easy to picture a scenario in which insurance companies demand that patient medicinal intake data be tracked and collected or else. Refuse to have your adherence tracked and you risk higher rates or even overall coverage. Maybe patients who don't take the digital pills suffer dire consequences financially or medically. "Maybe it becomes beneficial as much to health insurers and payers as it is to individual patients," Turner says.
In November 2017, the FDA approved the first-ever digital pill that includes a sensor, a drug called Abilify MyCite, made by Otsuka Pharmaceutical Company. The drug, which is yet to be released, is used to treat schizophrenia, bipolar disorder, and depression. With a built-in sensor developed by Proteus Digital Health, patients can give their doctors permission to see when exactly they are taking, or not taking, their meds. For patients with mental illness, the ability to help them stick to their prescribed regime can be life-saving.
But Turner wonders if Abilify is the best drug to be a forerunner for digital pills. Some people with schizophrenia might be suffering from paranoia, and perhaps giving them a pill developed by a large corporation that sends data from their body to be tracked by other people might not be the best idea. It could in fact exacerbate their sense of paranoia.
The Bottom Line: Protect the Data
We all have relatives who have pillboxes with separate compartments for each day of the week, or who carry pillboxes that beep when it's time to take the meds. But that's not always good enough for people with dementia, mental illness, drug addiction, or other life situations that make it difficult to remember to take their pills. Digital pills can play an important role in helping these people.
"The absolute principle here is that the data has to belong to the patient."
The one time the patient from Browne's study forgot to take his pills, he got a beeping reminder from his tablet that he'd missed a dose. "Taking a medication on a daily basis, sometimes we just forget, right?" he admits. "With our very accelerated lives nowadays, it helps us to remember that we have to take the medications. So patients are able to be on top of their own treatment."
Browne is convinced that digital pills can help people in developing countries with high rates of TB and HIV, though like Turner and Desai she cautions that patients' data must be protected. "I think it can be a tremendous technology for patient empowerment and I also think if properly used it can help the medical system to support patients that need it," she said. "But the absolute principle here is that the data has to belong to the patient."
Is Sex for Reproduction About to Become Extinct?
There are lots of great reasons we humans have sex. We mostly do it to pair bond, realize our primal urges, and feel good. Once in a while, we also do it to make babies. As the coming genetic revolution plays out, we'll still have sex for most of the same reasons we do today. But we'll increasingly not do it to procreate.
Protecting children from harm is one of the core responsibilities of parenting.
Most parents go to great lengths to protect their children from real and imagined harms. This begins with taking prenatal vitamins during pregnancy and extends to having children immunized and protected from exposures to various diseases and dangers. Most of us look askance for good reason at mothers who abuse controlled substances during their pregnancies or parents who choose to not immunize their children. Protecting children from harm is one of the core responsibilities of parenting.
In the United States today, up to two percent of babies are estimated to be born with rare genetic diseases caused by single gene mutations. Sickle cell disease, Tay-Sachs, and Huntington's disease are among the more well-known examples of these, but the list runs to the thousands. Many babies born with these disorders suffer terribly, some die young, and nearly all spend big chunks of their lives struggling through the medical system.
Increasingly, however, many of these single-gene mutation diseases and other chromosomal disorders like Down syndrome are being identified in non-invasive prenatal tests performed on expectant mothers at the end of their first trimester of pregnancy. Knowing the hardship that children born with these types of disorders will likely face, majorities of these women in countries around the world are choosing to terminate pregnancies once these diagnoses have been made. Whatever the justification and whatever anyone's views on the morality of abortion, these decisions are inherently excruciating.
A much smaller number of prospective mothers, however, are today getting this same information about their potential future children before their pregnancies even begin. By undergoing both in vitro fertilization (IVF) and preimplantation genetic testing (PGT), these women are able to know which of the eggs that have been surgically extracted from them and fertilized with their partner or donor's sperm will carry the dangerous mutations. The in vitro embryos with these disorders are simply not implanted in the expectant mother's womb.
It would be monstrous to assert that an existing person with a deadly disease has any less right to thrive than anyone else. But it would also be hard to make a case that parents should affirmatively choose to implant embryos carrying such a disease if given the option. If prospective parents are already today choosing not to implant certain embryos based on our preliminary understanding of disease risk, what will happen when this embryo selection is based on far more information than just a few thousand single gene mutation diseases?
Our ability and willingness to make genetic alterations to our future children will grow over time along with our knowledge and technological ability.
When the first human genome was sequenced in 2003, the race to uncover the mysteries of human genetics had only just begun. Although we still know very little about our genetics relative to the complexity of the genome and even less compared to the broader ecosystem of our biology, the progress toward greater understanding is astounding. Today, the number of single gene mutation diseases and relatively simple genetic traits that can be predicted meaningfully from genetic data alone is already significant.
In the not-distant future, this list will grow to include complex diseases and disease propensities, percentage probabilities of living a long and healthy life, and increasingly the genetic component of complex human attributes like height, IQ, and personality style. This predictive power of genetic analysis will funnel straight into our fertility clinics where prospective parents choosing embryos will be making ever more consequential decisions about the genetic components of the future lives, health, and capabilities of their children.
Our understanding of what the genes extracted from early stage pre-implanted embryos are telling us will be only one of the rocket boosters driving assisted reproduction forward. Another will be the ability to induce adult cells like skin and nucleated blood cells into stem cells and then turn those stem cells into egg progenitor cells and then ultimately eggs. This will not only eliminate the need for hormone treatments and surgery to extract human eggs but also make it easy and cheap to generate an unlimited number of eggs from a given woman.
The average woman has around fifteen eggs extracted during IVF but imagine what generating a thousand eggs will do to the range of possibilities that could be realized through pre-implantation embryo selection. Each of these thousand eggs would be the natural offspring of the two parents, but the variation between them would make it possible to choose the ones with the strongest expression of the genetic component of a particular desired trait – like those with the highest possible genetic IQ potential.
Another rocket booster will be the application of gene editing technologies like CRISPR to edit the genomes of pre-implanted embryos or of the sperm and eggs used to create them. Just this week, Chinese researchers announced they had used CRISPR to edit the CCR5 gene in the pre-implanted embryos of a pair of Chinese twins to make them immune to HIV, the first ever case of gene editing humans and a harbinger of our genetically engineered future. The astounding complexity of the human genome will put limits on our ability to safely make too many simultaneous genetic changes to human embryos, but our ability and willingness to make these types of alterations to our future children will grow over time along with our knowledge and technological ability.
With so much at stake, prospective parents will increasingly have a stark choice when determining how to conceive their children. If they go the traditional route of sex, they will experience both the benign wisdom and unfathomable cruelty of nature. If they use IVF and increasingly informed embryo selection, they will eliminate most single gene mutation diseases and likely increase their children's chances of living a longer and healthier life with more opportunity than their unenhanced peers. But the optimizing parents could also set up their children for misery if these children don't particularly enjoy what they have been optimized to become or see themselves as some type of freakish consumer product with emotions.
Conceiving though sex will come to be seen more and more like not immunizing your children is today, a perfectly natural choice that comes with a significant potential risk and expense.
But although there will be pros and cons on each side, the fight between conception through good old-fashioned sex and conception in the lab will ultimately not be fair. Differences and competition within and between societies will pressure parents and societies to adopt ever more aggressive forms of reproductive technology if they believe doing so will open possibilities and create opportunities for the next generations rather than close them.
Conception through sex will remain as useful as it has always been but lab conception will only get more advantageous. Over time, only zealots will choose to roll the dice of their future children's health and well-being rather than invest, like parents always have, in protecting their children from harm and helping optimize their life potential. Conceiving though sex will come to be seen more and more like not immunizing your children is today, a perfectly natural choice that comes with a significant potential risk and expense to yourself, your children, and your community.
As this future plays out, the genetics and assisted reproduction revolutions will raise enormous, thorny, and massively consequential questions about how we value and invest in diversity, equality, and our own essential humanity – questions we aren't remotely prepared to answer. But these revolutions are coming sooner than most of us understand or are prepared for so we had better get ready.
Because where this trail is ultimately heading goes well beyond sex and toward a fundamental transformation of our evolutionary process as a species – and that should be everybody's business.