France Daigle of the University of Montreal in Canada will identify the microorganisms that enable the survival of the typhoid fever-causing bacterium, Salmonella enterica serovar Typhi, at low levels in water, and thereby enhances disease spread. Typhoid fever spreads through contaminated food and water, and results in over 125,000 deaths annually worldwide. S. Typhi are so-called auxotrophic bacteria because they rely on an external source of the essential amino acids that they need to grow. Microbial interactions may provide nutrients and also increase bacterial fitness and support persistence by protecting them from the environment, thereby increasing the rate of disease transmission. They will assemble a microbial community in water consisting of three components: one protozoan (from a group known to promote bacterial survival); a defined consortium of bacteria representative of the human fecal microbiota; and fluorescently-tagged S. Typhi. They will evaluate the ability of S. Typhi to grow in these microcosms, and how they grow, such as in biofilms or inside the protozoa. They will also determine whether these persistent S. Typhi are better able to infect and survive in human cells. Finally, water samples from an endemic region in East Africa will be analyzed for the presence of S. Typhi and identified beneficial microbial partners using quantitative PCR.

Matthew DeLisa of Cornell University in the U.S. will create a cell-free synthetic biology platform for low-income settings that produces thermostable polysaccharide-based conjugate vaccines against diarrheal pathogens upon the addition of water to a single tube. Half-a-million children under age five die each year from diarrhea and dysentery, the majority in low- and middle-income countries. Two major causes of bacterial diarrhea are enterotoxigenic E. coli (ETEC) and Shigella strains. Conjugate vaccines combine multiple antigens into one vaccine to increase its activity. However, they require a complex manufacturing process, living cells, and refrigerated storage, which limit their application in developing countries. They will develop the materials and methods for manufacturing thermostable anti-diarrheal vaccines in single tubes that only require the addition of water just ahead of administration. The tubes will contain a plasmid that can express an FDA-approved carrier protein, along with selected O-antigen-polysaccharides from ETEC or Shigella strains, and an enzyme that can conjugate the two via glycosylation, all within a freeze-dried pellet. Following development, they will test the safety, scalability and portability of the vaccines, and characterize their ability to generate effective antibodies that can kill the bacteria. The system is expected to reduce conjugate vaccine costs, and its modular nature will facilitate expansion to other vaccine-preventable diseases.

Robert Kingsley of the Quadram Institute Bioscience in the United Kingdom will locate the typhoid fever-causing bacteria S. Typhi in water reservoirs in Harare, Zimbabwe, and identify any associated protozoa species present in the water that may be supporting disease spread. Typhoid fever is endemic in Zimbabwe, with several major outbreaks reported in the last decade. The bacteria persist in unclean aquatic environments, possibly supported by protozoa, and are transmitted to humans through ingestion of contaminated drinking water. They will detect S. Typhi in sewage effluent and low-quality drinking water in hotspots of typhoid transmission by enrichment culture and PCR, and use whole genome sequencing to establish the phylogenetic relationship between these bacteria and clinical typhoid isolates in the same city. They will also amplify 18S rDNA from the sewage and drinking water samples to characterize the microbial community in water and define the protozoa population. These data will help identify potential synergistic interactions between S. Typhi and other microbes to inform prevention strategies.

Hasan Uludag of RJH Biosciences in Canada will develop an affordable immunotherapy system based on genome-integrating transposons that works inside the body for the treatment of a wide variety of diseases such as cancer and diabetes. Emerging immunotherapies offer promising treatment for many diseases, but they require genetic modification of immune cells outside the body, and are thus labor intensive and expensive, limiting their utility in developing countries. They will use engineered nanoparticles in a new approach to immunotherapy that modifies immune cells inside the body. The nanoparticles are derived from polymeric materials that can encapsulate nucleic acids and proteins and release them into host cells. These nanoparticles will be dispersed in a hydrogel matrix with immunostimulatory molecules to create a living bioreactor inside the host that will attract and genetically modify immune cells. They will select polymers for their ability to deliver DNA-based transposons (to facilitate integration into the host genome) to immune cells and to stably express a reporter gene. Optimal polymers will be transferred into mice and they will evaluate transfection efficiency into immune cells with a fluorescent reporter gene. Finally, they will test the therapeutic efficacy of their in situ immune cell engineering approach in a mouse leukemia model.