Hi there, and welcome to our first post as team CHaD. We are currently two and a half weeks into our project and have a lot to report!

Cercarial Helminth activity Detector  (CHaD)

First of all, let’s explain what we are doing. In basic terms, our idea is to create a simple parasite detection method for use in infected water. The parasite we are attempting to detect is called a Schistosome, and causes the disease Schistosomiasis (also known as Bilharzia).

Schistosomiasis is a truly devestating condition and cripples rural communities in some of the poorest areas of the world. The condition ranks second only to malaria as the most common parasitic disease. More information can be found here: http://www.globalnetwork.org/schistosomiasis

In order to show the presence of the parasite, we are going to focus detection on the cercarial stage of the trematode lifecycle, this is the stage in which the parasite is infectious to humans.

Our detector will hinge on detection of the █████ase enzyme which is released by the parasite to enable it to burrow through the harder █████in-rich layers of sub dermal tissue in humans. We aim to illicit a colour change associated with the activity of this █████ase, and thus show the presence of cercarial schistosome in water.

For the purposes of our project we are focussing on the S. mansoni species of schistosome, prevalent throughout Africa and the Neotropics however, once developed, we believe our detector should be effective at detecting all human-pathogenic species of the parasite.

Two design plans, one aim 

Over the course of the 8 weeks we are going to concurrently follow two separate design plans in order to create our detector. The purpose of this is that if any major problems become associated with the protocol of one plan we can shift our efforts to focus on the other method.

Both plans have some features in common:

We are going to assemble a wax-based trap, made with addition of certain chemicals including poly-unsaturated oils and [REDACTED]. This trap will serve two purposes:

Firstly it should promote chemotaxis within the schistosomes, it has been shown that cercariae will move towards certain chemicals present in solution. To this extent, nail varnish has been used as an effective trap for the cercariae in the past. We aim to make the cercariae move towards and burrow into our wax based trap.  This trap should act as an effective barrier to separate our sensitive detector agents from any free proteases or other parasites present in the solution

The chemicals in trap will also promote the release of the enzyme █████ase by the parasite. Unlike the parasite which will become stuck in the wax trap this enzyme will be able to diffuse through the wax and initiate a colour change in the detector agents we are using.

The differences in the two design plans are determined by the agents used to produce a colour change

Henry’s Plan A

In this plan we aim to dye █████in, and crosslink or glue this protein to our wax trap. If █████ase is released it will cleave our dyed █████in protein, and dye will be eluted into the surrounding solution.  A colour change from colourless to (dye colour) will be observed in the solution by this method. 

Plan B 

We are going to use a chemical called [REDACTED] or colloquially SAPNA. This is a substrate homologue of █████in, which is to say it has a very similar structure to █████in and will be cleaved in a similar fashion by the █████ase enzyme. When it is cleaved the p-███████████ group is released, this will produce a yellow colour in the wax. A colour change from colourless to yellow will be observed in the wax by this method. 

Questions/Inquiries: ek2614@ic.ac.uk

 

Protein dying is a dangerous business.