Cholera is responsible for thousands of deaths each year worldwide. It can be fatal within hours of infection. However, a new vaccine made from rice specially grown offers hope of reducing that number.Although oral cholera vaccines for oral infection are available, they don't need refrigeration. It is also relatively easy to make, as rice grains are ground into a powder which needs to be mixed in liquid.The MucoRice CTB vaccine had previously been proven effective in animals. Phase 1 trials have now been completed in humans. There was a positive immune response and no side effects in 30 volunteers who participated in the trial.Hiroshi Kiyono from the University of Tokyo, Japan, said that he is optimistic about the future of MucoRice CTB vaccine. This was mainly because of the dose escalation result."Participants received the vaccine at low, medium, and high doses with the strongest immune responses at the highest dose."Over the course of eight weeks, the volunteers received four doses of different sizes. Another 30 participants were given placebo doses. The vaccine produced IgA antibodies and IgG antibodies that were specific to choleratoxin B (CTB) in those who received it.The vaccine is made from genetically modified Japanese short grain rice plants that have been grown indoors in a hydroponic greenhouse. CTB is produced by the plants, which produce a non-toxic amount that the immune system can detect and respond to. The rice is then ground into powder and stored in aluminum containers.The researchers found that the rice was mixed with salt to be eaten in these tests. However, water should be equally effective. The vaccine is then absorbed into the body via the intestinal mucosal membranes, much in the same manner as germs. This triggers a response.Kiyono says that rice protein bodies act like natural capsules to deliver antigen to the gut immune systems.The results were encouraging for many participants in the study. Follow-ups were done up to 16 weeks afterward. However, 11 of the 30 vaccine recipients showed either a low or no immune response.Researchers believe this could be due to the fact that different microbes in the gut respond differently to CTB. Although the link between immunity and gut microbiome is well-established, the details are not yet clear.These trials were larger and more diverse, and all of the participants were healthy Japanese men. However, these early results are encouraging.Variations in gut bacteria may limit vaccine effectiveness in developing nations, as suggested previously. This could be due to poor sanitation or the effects on the digestive system.Kiyono says that although it's speculation at the moment, higher microflora diversity could create a stronger immune response to the oral vaccine."Probably, for every vaccine right now, even injectable vaccines, we should consider the immune status of an individual based upon their microflora."The Lancet Microbe published the research.
