The Institute of Medical Science, the University of Tokyo and Astellas Pharma Inc. announced that they have signed a new collaborative development agreement on the rice-based oral vaccine “MucoRice-CTB” (MucoRice) against cholera and enterotoxigenic Escherichia coli (E coli) caused diarrheal diseases.

MucoRice is a rice-based oral vaccine expressing cholera toxin B subunit (CTB) in the intrinsic storage protein of rice using genetic engineering, which was developed by Prof. Hiroshi Kiyono, Project researcher Yoshikazu Yuki and their colleagues at International Research Development Center for Mucosal Vaccines (IMSUT).

In developing countries, diarrhea caused by pathogenic bacteria such as Vibrio cholerae and enterotoxigenic E coli, is one of the major causes of death among infants. At present, the challenges of the cholera vaccines used in developing countries are the need for the cold chain and the ineffectiveness against enterotoxigenic E coli. MucoRice is stable at room temperature and easily produced, therefore it is expected to meet the unmet medical needs of existing cholera vaccines. Under the MEXT (Ministry of Education, Culture, Sports, Science and Technology) and the AMED (Japan Agency for Medical Research and Development) Translational Research Network Program, an investigator-initiated phase 1 trial of this vaccine is nearing completion at IMSUT hospital (Principal investigator, Assoc. Prof. Osamu Hosono) in Japan. Data from this trial is now being analyzed.

Under the contract, IMSUT provides clinical trial materials and trial data, etc. which are necessary for the phase 1 and phase 2 trials of MucoRice for cholera and enterotoxigenic E coli., and Astellas is responsible for conducting and managing the clinical trials.

Through the collaborative development, IMSUT and Astellas will develop vaccines against infectious diseases affecting developing countries and hope we can address Access to Health issues.

Cholera is an acute gastroenteritis by Vibrio cholera which produce cholera toxin causing severe diarrhea. It is spread through contaminated food or water, therefore it is more common in developing countries.

Enterotoxigenic E coli is the E coli which produces a toxin that causes diarrhea and abdominal pain in humans. Severe diarrhea is caused by ingesting food or water contaminated by it. It is common in areas that lacks an adequate environmental sanitation, responsible for diarrhea in infants, and is also known to be a major cause of diarrhea in tourists who visit these areas.

Cholera toxin consists of 2 types of subunits, CTA (chorea toxin A subunit) is toxic, and CTB pentamer adheres to epithelial cells and delivers CTA into the cell.

The cold chain is a system to store and transport vaccine at a constant low temperature to maintain its effect.