Simplified method for detecting antibodies

A Ben-Gurion University research team, headed by Dr. Raz Jelinek, has recently designed one of the simplest, most rapid approaches to detect specific antibodies.

Technicians merely add a blue liquid to an antibody containing solution. If the colour changes to red (a reaction taking from seconds to a few minutes) the antibody they are looking for is present. Standard procedures usually require many steps and sophisticated measuring equipment to accomplish the same task, with results available only after several hours.

The diagnostic approach was verified in a model system consisting of protein fragments and antibodies that recognise and bind those fragments. There is now no barrier to develop parallel reagents containing fragments of proteins produced by specific viruses, which would detect the antiviral antibodies in blood serum.

This mix-and-observe approach could be used in a doctor's office, small clinics and rural third-world communities, far from major diagnostic laboratories. Moreover, an inexpensive colorimeter, which measures light absorption by liquids, could be used to provide a quantitative measure of antibody levels.

The calorimetric approach to detect antibody binding is built around simple water-dispersed particles with the characteristics of natural biological membranes. The particles are composed of three components: lipids, fat-like molecules that are the basis of normal biologic membranes; a specially designed lipid scaffold polymer known as a conjugated polydiacetylene; and membrane-soluble molecules containing epitopes, the protein fragments that are recognised by the antibody under test.

When in the undisturbed particle, polydiacetylene gives the solution a blue colour. However, when added to an antibody that recognises and binds the epitope, the three-factor particle is structurally disrupted, causing the polydiacetylene to turn red.