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."
One of the Netherlands’ most famous pieces of pop culture is “Soldier of Orange.” It’s the title of the country’s most celebrated war memoir, movie and epic stage musical, all of which detail the exploits of the nation’s resistance fighters during World War II.
Willem Johan Kolff was a member of the Dutch resistance, but he doesn’t rate a mention in the “Solider of Orange” canon. Yet his wartime toils in a rural backwater not only changed medicine, but the world.
Kolff had been a physician less than two years before Germany invaded the Netherlands in May 1940. He had been engaged in post-graduate studies at the University of Gronigen but withdrew because he refused to accommodate the demands of the Nazi occupiers. Kolff’s Jewish supervisor made an even starker choice: He committed suicide.
After his departure from the university, Kolff took a job managing a small hospital in Kampen. Located 50 miles from the heavily populated coastal region, the facility was far enough away from the prying eyes of Germans that not only could Kolff care for patients, he could hide fellow resistance fighters and even Jewish refugees in relative safety. Kolff coached many of them to feign convincing terminal illnesses so the Nazis would allow them to remain in the hospital.
Despite the demands of practicing medicine and resistance work, Kolff still found time to conduct research. He had been haunted and inspired when, not long before the Nazi invasion, one of his patients died in agony from kidney disease. Kolff wanted to find a way to save future patients.
He broke his problem down to a simple task: If he could remove 20 grams of urea from a patient’s blood in 24 hours, they would survive. He began experimenting with ways to filter blood and return it to a patient’s body. Since the war had ground all non-military manufacturing to a halt, he was mostly forced to make do with material he could find at the hospital and around Kampen. Kolff eventually built a device from a washing machine parts, juice cans, sausage casings, a valve from an old Ford automobile radiator, and even scrap from a downed German aircraft.
The world’s first dialysis machine was hardly imposing; it resembled a rotating drum for a bingo game or raffle. Yet it carried on the highly sophisticated task of moving a patient’s blood through a semi-permeable membrane (about a 50-foot length of sausage casings) into a saline solution that drew out urea while leaving the blood cells untouched.
In emigrating to the U.S. to practice medicine, Kolff's intent was twofold: Advocate for a wider adoption of dialysis, and work on new projects. He wildly succeeded at both.
Kolff began using the machine to treat patients in 1943, most of whom had lapsed into comas due to their kidney failure. But like most groundbreaking medical devices, it was not an immediate success. By the end of the war, Kolff had dialyzed more than a dozen patients, but all had died. He briefly suspended use of the device after the Allied invasion of Europe, but he continued to refine its operation and the administration of blood thinners to patients.
In September 1945, Kolff dialyzed another comatose patient, 67-year-old Sofia Maria Schafstadt. She regained consciousness after 11 hours, and would live well into the 1950s with Kolff’s assistance. Yet this triumph contained a dark irony: At the time of her treatment, Schafstadt had been imprisoned for collaborating with the Germans.
With a tattered Europe struggling to overcome the destruction of the war, Kolff and his family emigrated to the U.S. in 1950, where he began working for the Cleveland Clinic while undergoing the naturalization process so he could practice medicine in the U.S. His intent was twofold: Advocate for a wider adoption of dialysis, and work on new projects. He wildly succeeded at both.
By the mid-1950s, dialysis machines had become reliable and life-saving medical devices, and Kolff had become a U.S. citizen. About that time he invented a membrane oxygenator that could be used in heart bypass surgeries. This was a critical component of the heart-lung machine, which would make heart transplants possible and bypass surgeries routine. He also invented among the very first practical artificial hearts, which in 1957 kept a dog alive for 90 minutes.
Kolff moved to the University of Utah in 1967 to become director of its Institute for Biomedical Engineering. It was a promising time for such a move, as the first successful transplant of a donor heart to a human occurred that year. But he was interested in going a step further and creating an artificial heart for human use.
It took more than a decade of tinkering and research, but in 1982, a team of physicians and engineers led by Kolff succeeded in implanting the first artificial heart in dentist Barney Clark, whose failing health disqualified him from a heart transplant. Although Clark died in March 1983 after 112 days tethered to the device, that it kept him alive generated international headlines. While graduate student Robert Jarvik received the named credit for the heart, he was directly supervised by Kolff, whose various endeavors into artificial organ research at the University of Utah were segmented into numerous teams.
Forty years later, several artificial hearts have been approved for use by the Food and Drug Administration, although all are a “bridge” that allow patients to wait for a transplant.
Kolff continued researching and tinkering with biomedical devices – including artificial eyes and ears – until he retired in 1997 at the age of 86. When he died in 2009, the medical community acknowledged that he was not only a pioneer in biotechnology, but the “father” of artificial organs.
The "Making Sense of Science" podcast features interviews with leading experts about health innovations and the ethical questions they raise. The podcast is hosted by Matt Fuchs, editor of Leaps.org, the award-winning science outlet.
My guest today is Nanea Reeves, the CEO of TRIPP, a wellness platform with some big differences from meditation apps you may have tried like Calm and Headspace. TRIPP's experiences happen in virtual reality, and its realms are designed based on scientific findings about states of mindfulness. Users report feelings of awe and wonder and even mystical experiences. Nanea brings over 15 years of leadership in digital distribution, apps and video game technologies. Before co-founding TRIPP, she had several other leadership roles in tech with successful companies like textPlus and Machinima. Read her full bio below in the links section.
Nanea Reeves, CEO of TRIPP.
TRIPP
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This conversation coincided with National Brain Awareness Week. The topic is a little different from the Making Sense of Science podcast’s usual focus on breakthroughs in treating and preventing disease, but there’s a big overlap when it comes to breakthroughs in optimal health. Nanea’s work is at the leading edge of health, technology and the science of wellness.
With TRIPP, you might find yourself deep underwater, looking up at the sunlight shimmering on the ocean surface, or in the cosmos staring down at a planet glowing with an arresting diversity of colors. Using TRIPP for the past six months has been a window for me into the future of science-informed wellness and an overall fascinating experience, as was my conversation with Nanea.
Show notes:
Nanea and I discuss her close family members' substance addictions and her own struggle with mental illness as a teen, which led to her first meditation experiences, and much more:
- The common perception that technology is an obstacle for mental well-being, a narrative that overlooks how tech can also increase wellness when it’s designed right.
- Emerging ways of measuring meditation experiences by recording brain waves - and the shortcomings of the ‘measured self’ movement.
- Why TRIPP’s users multiplied during the stress and anxiety of the pandemic, and how TRIPP can can be used to enhance emotional states.
- Ways in which TRIPP’s visuals and targeted sound frequencies have been informed by innovative research from psychologists like Johns Hopkins’ Matthew Johnson.
- Ways to design apps and other technologies to better fulfill the true purpose of mindfulness meditation. (Hint: not simply relaxation.)
- And of course, because the topic is mental wellness and tech, I had to get Nanea's thoughts on Elon Musk, Neuralink and brain machine interfaces.
Here are links for learning more about TRIPP:
- TRIPP website: https://www.tripp.com/about/
- Nanea Reeves bio: https://www.tripp.com/team/nanea-reeves/
- Study of data collected by UK's Office for National Statistics on behavior during the pandemic, which suggests that TRIPP enhanced users' psychological and emotional mindsets: https://link.springer.com/chapter/10.1007/978-3-03...
- Research that's informed TRIPP: https://www.tripp.com/research/
- Washington Post Top Pick at CES: https://www.washingtonpost.com/technology/2019/01/...
- TRIPP's new offering, PsyAssist, to provide support for ketamine-assisted therapy: https://www.mobihealthnews.com/news/tripp-acquires...
- Randomized pilot trial involving TRIPP: https://bmjopen.bmj.com/content/bmjopen/11/4/e0441...