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."
“Young Blood” Transfusions Are Not Ready For Primetime – Yet
A young woman donates blood.
The world of dementia research erupted into cheers when news of the first real victory in a clinical trial against Alzheimer's Disease in over a decade was revealed last October.
By connecting the circulatory systems of a young and an old mouse, the regenerative potential of the young mouse decreased, and the old mouse became healthier.
Alzheimer's treatments have been famously difficult to develop; 99 percent of the 200-plus such clinical trials since 2000 have utterly failed. Even the few slight successes have failed to produce what is called 'disease modifying' agents that really help people with the disease. This makes the success, by the midsize Spanish pharma company Grifols, worthy of special attention.
However, the specifics of the Grifols treatment, a process called plasmapheresis, are atypical for another reason - they did not give patients a small molecule or an elaborate gene therapy, but rather simply the most common component of normal human blood plasma, a protein called albumin. A large portion of the patients' normal plasma was removed, and then a sterile solution of albumin was infused back into them to keep their overall blood volume relatively constant.
So why does replacing Alzheimer's patients' plasma with albumin seem to help their brains? One theory is that the action is direct. Alzheimer's patients have low levels of serum albumin, which is needed to clear out the plaques of amyloid that slowly build up in the brain. Supplementing those patients with extra albumin boosts their ability to clear the plaques and improves brain health. However, there is also evidence suggesting that the problem may be something present in the plasma of the sick person and pulling their plasma out and replacing it with a filler, like an albumin solution, may be what creates the purported benefit.
This scientific question is the tip of an iceberg that goes far beyond Alzheimer's Disease and albumin, to a debate that has been waged on the pages of scientific journals about the secrets of using young, healthy blood to extend youth and health.
This debate started long before the Grifols data was released, in 2014 when a group of researchers at Stanford found that by connecting the circulatory systems of a young and an old mouse, the regenerative potential of the young mouse decreased, and the old mouse became healthier. There was something either present in young blood that allowed tissues to regenerate, or something present in old blood that prevented regeneration. Whatever the biological reason, the effects in the experiment were extraordinary, providing a startling boost in health in the older mouse.
After the initial findings, multiple research groups got to work trying to identify the "active factor" of regeneration (or the inhibitor of that regeneration). They soon uncovered a variety of compounds such as insulin-like growth factor 1 (IGF1), CCL11, and GDF11, but none seemed to provide all the answers researchers were hoping for, with a number of high-profile retractions based on unsound experimental practices, or inconclusive data.
Years of research later, the simplest conclusion is that the story of plasma regeneration is not simple - there isn't a switch in our blood we can flip to turn back our biological clocks. That said, these hypotheses are far from dead, and many researchers continue to explore the possibility of using the rejuvenating ability of youthful plasma to treat a variety of diseases of aging.
But the bold claims of improved vigor thanks to young blood are so far unsupported by clinical evidence.
The data remain intriguing because of the astounding results from the conjoined circulatory system experiments. The current surge in interest in studying the biology of aging is likely to produce a new crop of interesting results in the next few years. Both CCL11 and GDF11 are being researched as potential drug targets by two startups, Alkahest and Elevian, respectively.
Without clarity on a single active factor driving rejuvenation, it's tempting to try a simpler approach: taking actual blood plasma provided by young people and infusing it into elderly subjects. This is what at least one startup company, Ambrosia, is now offering in five commercial clinics across the U.S. -- for $8,000 a liter.
By using whole plasma, the idea is to sidestep our ignorance, reaping the benefits of young plasma transfusion without knowing exactly what the active factors are that make the treatment work in mice. This space has attracted both established players in the plasmapheresis field – Alkahest and Grifols have teamed up to test fractions of whole plasma in Alzheimer's and Parkinson's – but also direct-to-consumer operations like Ambrosia that just want to offer patients access to treatments without regulatory oversight.
But the bold claims of improved vigor thanks to young blood are so far unsupported by clinical evidence. We simply haven't performed trials to test whether dosing a mostly healthy person with plasma can slow down aging, at least not yet. There is some evidence that plasma replacement works in mice, yes, but those experiments are all done in very different systems than what a human receiving young plasma might experience. To date, I have not seen any plasma transfusion clinic doing young blood plasmapheresis propose a clinical trial that is anything more than a shallow advertisement for their procedures.
The efforts I have seen to perform prophylactic plasmapheresis will fail to impact societal health. Without clearly defined endpoints and proper clinical trials, we won't know whether the procedure really lowers the risk of disease or helps with conditions of aging. So even if their hypothesis is correct, the lack of strong evidence to fall back on means that the procedure will never spread beyond the fringe groups willing to take the risk. If their hypothesis is wrong, then people are paying a huge amount of money for false hope, just as they do, sadly, at the phony stem cell clinics that started popping up all through the 2000s when stem cell hype was at its peak.
Until then, prophylactic plasma transfusions will be the domain of the optimistic and the gullible.
The real progress in the field will be made slowly, using carefully defined products either directly isolated from blood or targeting a bloodborne factor, just as the serious pharma and biotech players are doing already.
The field will progress in stages, first creating and carefully testing treatments for well-defined diseases, and only then will it progress to large-scale clinical trials in relatively healthy people to look for the prevention of disease. Most of us will choose to wait for this second stage of trials before undergoing any new treatments. Until then, prophylactic plasma transfusions will be the domain of the optimistic and the gullible.
Who’s Responsible for Curbing the Teen Vaping Epidemic?
A teenage girl vaping in a park.
E-cigarettes are big business. In 2017, American consumers bought more than $250 million in vapes and juice-filled pods, and spent $1 billion in 2018. By 2023, the global market could be worth $44 billion a year.
"My nine-year-old actually knows what Juuling is. In many cases the [school] bathroom is now referred to as 'the Juuling room.'"
Investors are trying to capitalize on the phenomenal growth. In July 2018, Juul Labs, the company that owns 70 percent of the U.S. e-cigarette market share, raised $1.25 billion at a $16 billion valuation, then sold a 35 percent stake to Phillip Morris USA owner Altria Group in December. The second transaction valued the company at $38 billion. While the traditional tobacco market remains much larger, it's projected to grow at less than two percent a year, making the attractiveness of the rapidly expanding e-cigarette market obvious.
While Juul and other e-cigarette manufacturers argue that their products help adults quit smoking – and there's some research to back this narrative up – much of the growth has been driven by children and teenagers. One CDC study showed a 48 percent rise in e-cigarette use by middle schoolers and a 78 percent increase by high schoolers between 2017 and 2018, a jump from 1.5 million kids to 3.6 million. In response to the study, F.D.A. Commissioner Scott Gottlieb said, "We see clear signs that youth use of electronic cigarettes has reached an epidemic proportion."
Another study found that teenagers between 15 and 17 were 16 times more likely to use Juul than people aged 25-34. In December, Surgeon General Jerome Adams said, "My nine-year-old actually knows what Juuling is. In many cases the [school] bathroom is now referred to as 'the Juuling room.'"
And the product is seriously addictive. A single Juul pod contains as much nicotine as a pack of 20 regular cigarettes. Considering that 90 percent of smokers are addicted by 18 years old, it's clear that steps need to be taken to combat the growing epidemic.
But who should take the lead? Juul and other e-cigarette companies? The F.D.A. and other government regulators? Schools? Parents?
The Surgeon General's website has a list of earnest possible texts that parents can send to their teens to dissuade them from Juuling, like: "Hope none of your friends use e-cigarettes around you. Even breathing the cloud they exhale can expose you to nicotine and chemicals that can be dangerous to your health." While parents can attempt to police their teens, many experts believe that the primary push should come at a federal level.
The regulation battle has already begun. In September, the F.D.A. announced that Juul had 60 days to show a plan that would prevent youth from getting their hands on the product. The result was for the company to announce that it wouldn't sell flavored pods in retail stores except for tobacco, menthol, and mint; Juul also shuttered its Instagram and Facebook accounts. These regulations mirrored an F.D.A. mandate two days later that required flavored e-cigarettes to be sold in closed-off areas. "This policy will make sure the fruity flavors are no longer accessible to kids in retail sites, plan and simple," Commissioner Gottlieb said when announcing the moves. "That's where they're getting access to the e-cigs and we intend to end those sales."
"There isn't a great history of the tobacco industry acting responsibly and being able to in any way police itself."
While so far, Gottlieb – who drew concerns about conflict of interest due to his past position as a board member at e-cigarette company, Kure – has pleased anti-smoking advocates with his efforts, some observers also argue that it needs to go further. "Overall, we didn't know what to expect when a new commissioner came in, but it's been quite refreshing how much attention has been paid to the tobacco industry by the F.D.A.," Robin Koval, CEO and president of Truth Initiative, said a day after the F.D.A. announced the proposed regulations. "It's important to have a start. I certainly want to give credit for that. But we were really hoping and feel that what was announced...doesn't go far enough."
The issue is the industry's inability or unwillingness to police itself in the past. Juul, however, claims that it's now proactively working to prevent young people from taking up its product. "Juul Labs and F.D.A. share a common goal – preventing youth from initiating on nicotine," a company representative said in an email. "To paraphrase Commissioner Gottlieb, we want to be the off-ramp for adult smokers to switch from cigarettes, not an on-ramp for America's youth to initiate on nicotine. We won't be successful in our mission to serve adult smokers if we don't narrow the on-ramp... Our intent was never to have youth use Juul products. But intent is not enough, the numbers are what matter, and the numbers tell us underage use of e-cigarette products is a problem. We must solve it."
Juul argues that its products help adults quit – even offering a calculator on the website showing how much people will save – and that it didn't target youth. But studies show otherwise. Furthermore, the youth smoking prevention curriculum the company released was poorly received. "It's what Philip Morris did years ago," said Bonnie Halpern-Felsher, a professor of pediatrics at Stanford who helped author a study on the program's faults. "They aren't talking about their named product. They are talking about vapes or e-cigarettes. Youth don't consider Juuls to be vapes or e-cigarettes. [Teens] don't talk about flavors. They don't talk about marketing. They did it to look good. But if you look at what [Juul] put together, it's a pretty awful curriculum that was put together pretty quickly."
The American Lung Association gave the FDA an "F" for failing to take mint and menthol e-cigs off the market, since those flavors remain popular with teens.
Add this all up, and in the end, it's hard to see the industry being able to police itself, critics say. Neither the past examples of other tobacco companies nor the present self-imposed regulations indicate that this will succeed.
"There isn't a great history of the tobacco industry acting responsibly and being able to in any way police itself," Koval said. "That job is best left to the F.D.A., and to the states and localities in what they can regulate and legislate to protect young people."
Halpern-Felsher agreed. "I think we need independent bodies. I really don't think that a voluntary ban or a regulation on the part of the industry is a good idea, nor do I think it will work," she said. "It's pretty much the same story, of repeating itself."
Just last week, the American Association of Pediatrics issued a new policy statement calling for the F.D.A. to immediately ban the sale of e-cigarettes to anyone under age 21 and to prohibit the online sale of vaping products and solutions, among other measures. And in its annual report, the American Lung Association gave the F.D.A. an "F" for failing to take mint and menthol e-cigs off the market, since those flavors remain popular with teens.
Few, if any people involved, want more regulation from the federal government. In an ideal world, this wouldn't be necessary. But many experts agree that it is. Anything else is just blowing smoke.