Cattle disease fight is kept in the family

When Dr Moira Desport dropped in to see a colleague at Murdoch University, with her husband Will Ditcham while on holiday in Western Australia, they did not expect it would eventually lead to a career move working towards wiping out Jembrana disease in Bali cattle.

Two years later, they are now both funded by the Australian Centre for International Agricultural Research, with more than $1 million towards the project for the next three years.

Dr Desport started her postdoctoral research with Professor Graham Wilcox from Murdoch's Division of Veterinary and Biomedical Sciences last year, attempting to find a vaccine for Jembrana disease. She had originally collaborated with Professor Wilcox eight years before while on a working honeymoon in Bali.

Her husband Will Ditcham also joined the research team recently, starting his PhD research.

Jembrana disease first swept through Bali in 1964, killing 30,000-70,000 Banteng cattle in the first 12 months before spreading to Java and Sumatra.

"We want to find a way to differentiate Jembrana disease from another closely related but harmless virus, bovine deficiency virus (BIV), as the two are indistinguishable with current immunological tests," said Dr Desport.

"However, what we are ultimately aiming to do is to find an effective vaccine."

The joint Indonesian/Murdoch team succeeded in creating a crude vaccine as an interim measure while the research for an improved vaccine continued.

"At the moment we use ground up spleen with inactivated viral components as a crude vaccine," said Dr Desport.

"However this technique is very expensive, not wholly reliable and requires refrigeration."

The research team is attempting to find a more stable, cheaper vaccine by testing combinations of three of the viral proteins that have already been cloned and expressed in bacteria by Murdoch PhD students.

Dr Desport and Mr Ditcham will trial these vaccine constructs based on cattle in Bali later this year.

"Once we find a construct that produces an appropriate response in the Bali cattle, we can pass the technology onto our colleagues at DIC in Bali and at Balitvet and LIPI Biotechnology in Java. Since this is only a problem in Indonesia it is important that the vaccine can be produced and monitored within Indonesia," said Dr Desport.

At the same time as this protein vaccine is trialled, Mr Ditcham is working towards a newer type of vaccine using DNA instead of protein.

"In a normal recombinant protein vaccine, we can use a bacterial or yeast expression system to produce viral protein for injection into the animal," said Mr Ditcham.

"With a DNA vaccine, which is still a new and very experimental technology, the viral gene(s) is introduced by use of a "gene gun" straight into the skin of a cow. The resulting expression of the viral antigen in the cow's own cells improves the chance of the immune response being protective, as the antigen produced will more closely resemble that found in a natural infection."

Mr Ditcham is working on the same three genes that are being trialled to produce the recombinant protein vaccine, and hopes the technology will be applicable in the future, particularly in Indonesia.

"We need a vaccine that is easy for farmers to use, able to withstand the climate and only needs one dose to work," said Mr Ditcham.

The first trials of the recombinant protein vaccine begin in Bali in October.