Panbio develops new type of antibody assay

Brisbane medical diagnostics developed Panbio (ASX:PBO) believes it has achieved a milestone in its efforts to develop a new type of antibody assay capable of directly detecting target antigens at low concentrations in antigenically complex biological fluids.

Executive chairman John Lee announced this week that the company's Advanced Technologies research team has selected, developed and validated the enzyme fragments required to make its Forced Enzyme Complementation System work in diagnostic assays.

Lee said his company believes it is the first to develop a homogenous assay system that will work in any setting from "a teacup in a Borneo jungle" to a modern automated laboratory, and deliver results within minutes, rather than hours.

PanBio's chief operating officer, Dr Stuart Hazel, said that current ELISA (enzyme-linked immunosorbent assay) technology involves multiple reagent steps and repeated washing that can take 2-3 hours to run.

PanBio's system is indendendent of the container - "You can do it in a coffee cup as easily as in a microtitre well," Hazel said.

The tests involves cleaving an chosen enzyme into two fragments, and linking one to an anti-idiotype antibody, and the other to an antigen. In the absence of the target antigen in solution, the two fragments stay separated and the enzyme is inactive.

But when the target antigen - say a capsid protein fragment from the dengue fever virus - is present, it bridges the two fragments, drawing them together and acivating the enzyme reaction, producing a yellow-to-red colour change in mixture that can be read automatically some 10 minutes later.

Hazel said that, from the user's perseptive, all that was required was to add a diluted sample to the assay, incubate and read it. "Our target is to have an assay that will work in 10 minutes," he said.

"It's platform-independent, so it can be fitted to any system, or used in the field. The end use is very simple, although the technology is elegant and inventive."

Previous efforts to homogeneous assay systems have suffered from high background 'noise' and poor sensitivity.

PanBio Advanced Technoologies division research manager Dr Edward Kachab described the advance as "a first and essential step, allowing us to move forward in developing prototype assays for infectious and other disease markers."

"With these results ... we can now talk with a level of confidence about realising a commercially viable homogeneous assay system," Hazell said. "We are now starting to activity promote the technology and begin discussions with potential parters interested in exploiting this technology with PanBio.

Hazell said the milestone reduces but does not eliminate the technical risk associated with PanBio's research program.