Researchers Create Edible Cholera Vaccine From Powdered Rice

MucoRiceCTB Cholera Vaccine
Image resized/University of Tokyo ┬ęDr. Hiroshi Kiyono

A novel vaccine to protect against deadly cholera which can be simply mixed with liquid and drunk is safe, results of the first human trial has shown.

The vaccine, named MucoRice-CTB, made by grinding up genetically modified grains of rice has shown no obvious side effects and a good immune response, said researchers from the University of Tokyo and Chiba University in Japan.

They have published the peer-reviewed results of the Phase 1 clinical trial of the vaccine in The Lancet Microbe.

The MucoRice-CTB vaccine is grown in rice plants and stimulates immunity through the mucosal membranes of the intestines. It remains stable at room temperature, can be stored and transported without refrigeration and does not need needles. It can be taken by simply mixing with liquid.

“I’m very optimistic for the future of our MucoRice-CTB vaccine, especially because of the dose escalation results. Participants responded to the vaccine at the low, medium and high doses, with the largest immune response at the highest dose,” said Professor Hiroshi Kiyono, from the Institute of Medical Science at the Tokyo University.

For the study, 30 volunteers received a placebo and groups of 10 volunteers received a total of four doses spaced every two weeks of either 3 milligrams (mg), 6 mg or 18 mg each of the vaccine.

Tests two and four months after receiving the last dose revealed that volunteers who responded to the vaccine had IgA and IgG antibodies — two types of proteins the immune system produces to fight infections — specific to cholera toxin B (CTB). Participants who received a higher dose of vaccine were more likely to have CTB-specific antibodies.

The new cholera vaccine grows in genetically modified Japanese short-grain rice plants in a purpose-built, indoor hydroponic farm. When the plants are mature, the rice is harvested and ground into a fine powder, then sealed in aluminum packets for storage. When people are ready to be vaccinated, the powder is mixed with about 90 milliliters (1/3 US cup) of liquid and then drunk.

Researchers have only tested the vaccine using saline (a salt solution equivalent to body fluids), but they expect it would work equally well with plain water.