Parasight – A synthetic biology approach for the detection of parasites

One of the primary goals of synthetic biology is the application-driven generation of new parts, circuits, and systems to solve problems that as yet have not been adequately addressed. The parasitic infection Schistosomiasis affects over 200 million people worldwide, with estimates suggesting that a further 780 million people are at risk of infection. The causative agents are fluke worms of the Schistosoma genus, and infection only occurs when the cercarial larvae are able to penetrate the skin. To facilitate this, the cercariae secrete an elastase possessing a defined substrate specificity. Our project takes advantage of this property of the cercarial elastase, and has used it to design and create biosensors that are specific in targeting Schistosoma. The design of our biosensors is based on a two-pronged approach, 1) an accurate detection system which is targeted to the cercarial elastase, and 2) an easily measurable output. Using synthetic biology approaches we have engineered the biosensors to be “housed” in two bacterial chassis, Bacillus subtilis and Escherichia coli. The B. subtilis biosensors comprise a fusion protein that possesses the cell wall binding domain of LytC along with our biosensor component, whilst the E. coli biosensors are composed of the CmpX protein, which traverses the outer membrane, fused with our biosensor component. Both biosensor components are presented to the external environment, and possess cercarial elastase recognition motifs, as well as either a streptavidin binding peptide for the E. coli biosensors, which can be detected by a streptavidin fluorophore conjugate, or a poly-histidine tag for the B. subtilis biosensors, which can be detected using a poly-histidine tag antibody fluorophore conjugate. Thus, when the elastase is present it cleaves the biosensor at the recognition motif site, thereby releasing the detectable components. Here we report and discuss the progress we have made in this important project and share some exciting data.