International interest in NZ TB test

Bryce Buddle undertaking a skin test

A new test for bovine TB developed by AgResearch is attracting international attention.

Principal Scientist Professor Bryce Buddle says it is early days yet, but they have encouraging preliminary results from a trial which shows the potential for a more accurate and cost-effective diagnostic test in the battle against bovine TB.

“The current test used on New Zealand farms often gives false positives, and a blood test is needed to confirm infection. We have developed a new skin test that has a similar sensitivity to the existing reagent bovine tuberculin, and fewer false positive reactions in non-infected animals,” he says.

Professor Buddle and colleagues from the Hopkirk Research Institute in Palmerston North have demonstrated that by displaying three or four specific M. bovis proteins on the surface of polyester beads (bionanoparticles), a cost-effective and more reliable skin test reagent for bovine TB can be produced.  The original beads technology, known as Biobeads, was developed by Professor Bernd Rehm at Massey University. Professor Rehm is the Chief Science Officer at the New Zealand biotechnology company PolyBatics Ltd, the company that now owns the technology and is developing products.

Professor Buddle says the advantage of this approach is that the proteins are stronger immune responses when displayed on very small particles and can be used in a very low concentration; in addition, the Biobeads can be produced at low cost using fermentation technology.

“This new reagent has the potential to be used in a TB diagnostic blood test and as well as the human skin test for tuberculosis,” he says.

A large field trial is currently underway to obtain estimates of sensitivity and specificity of the test in comparison with the existing bovine tuberculin.

Already more than 30,000 cattle and 3,000 deer have been tested and results for specificity have been very encouraging with significantly fewer false positives than that for bovine tuberculin and the test is on track to deliver equivalent sensitivity.

Professor Buddle says the new skin test reagent has attracted international attention and material has been supplied to the United States Department of Agriculture, and the United Kingdom Department for Environment, Food and Rural Affairs for testing of the reagent for TB diagnosis in cattle.

This work is funded by the Ministry of Business, Innovation and Employment as part of a five-year contract and PolyBatics Ltd is commercialising the new reagent.

Bovine TB is a chronic disease of animals caused by bacterium called Mycobacterium bovis (M. bovis), which is closely related to the bacteria that cause human and avian tuberculosis. Bovine TB can affect most mammals, causing illness, coughing and eventual death. The disease is contagious and spread by contact with infected domestic and wild animals. While the incidence of bovine TB has been greatly reduced within the developed world, significant pockets of infection remain within wildlife in New Zealand, the United Kingdom and to a lesser extent the United States and Canada, thus putting livestock within those countries at risk. Bovine TB remains a serious health risk for animals and humans alike in many less developed countries.

(From left to right) Bernd Rehm and his team from PolyBatics Ltd: Shuxiong Chen, Karin Kurz, Andy Hollings, Dr. Lydia Friedrich, Mark Venning-Slater, Sasha Atmadjaja.

(From left to right) Bernd Rehm and his team from PolyBatics Ltd: Shuxiong Chen, Karin Kurz, Andy Hollings, Dr. Lydia Friedrich, Mark Venning-Slater, Sasha Atmadjaja.