Bald cockies have nothing to crow about
It is a different story, however, for a bird. Certain species of birds in Australia are afflicted by a virus that affects them the same way men are afflicted by baldness. It is known as the circovirus, which causes bald cocky disease and retards the ability of cockatoos, budgerigars and parrots to grow feathers.Unfortunately, bald cocky disease is more than a cosmetic problem for our winged friends. Losing feathers exposes the bird to the cold and suppresses their immuno functions, making them more susceptible to diseases. Being bald also means the bird is unable to fly away from predators or to hunt for food, conditions which lead to almost certain death in the wild.The circovirus, which kills the cells of the feather and the beak, was first identified by scientists at Murdoch University in the 1970s. Dr Shane Raidal, who was then a student at Sydney University, subsequently developed a vaccine for the virus. But producing the vaccine, which is made from inactivated virus cells, is a painstaking and expensive process. It involves collecting feathers from naturally-diseased birds and a complicated purification of the virus from these feathers.
A synthetically produced recombinant vaccine would be easier and cheaper to manufacture, said Dr Raidal, who lectures in veterinary pathology at Murdoch University's School of Veterinary Science.Work done by one of Dr Raidal's PhD students, Mohammad Bassami, has moved scientists closer to producing such a recombinant vaccine. Mr Bassami received funding from the Iranian Government as part of an exchange program and successfully profiled the virus. Now that the characteristics of the virus were better understood, a vaccine could hopefully be developed within the next year, said Dr Raidal.In one sense, the virus was so simple that it seemed reasonable to assume a solution would also be simple, said Dr Raidal. But certain characteristics of the virus had presented problems.Firstly, the circovirus had a single strand of DNA that was circular in shape (hence its name). This made cloning more difficult compared with other viruses with straight line DNA.The circovirus is also the smallest virus capable of causing disease in any animal. While this in itself was interesting, it also made the work of scientists harder because the virus could not be seen in gels during scientific work. 
"In one sense it is so simple that traditionally we wouldn't have thought a virus like this was capable of causing disease," said Dr Raidal.While it is not realistic to use the vaccine for birds in the wild, a vaccine was still important to ensure that outbreaks of the disease in isolated pockets could be controlled.This was important given that the virus was serious enough to be considered a contributing factor in the decline of species such as the orange-bellied parrot, and may also be having detrimental effects on other native birds such as the Nerathra blue bonnet and the swift parrot.It was also a rather insidious disease, incubating anywhere from three weeks to two years, said Dr Raidal."All the time it could be spreading infection everywhere," he said.Unfortunately, disease in free-ranging birdlife had not been comprehensively addressed by the scientific community, said Dr Raidal. It was only bird species of economic importance (chickens, for example) or diseases in birds that posed a threat to public health that tended to get funding for scientific research.Furthermore birds also did not have the same public appeal as some charismatic wildlife, such as koalas or whales, said Dr Raidal.This meant research into disease in free-ranging bird life, such as bald cocky disease, had to be conducted on a shoe string budget."It's frustrating because it really slows things down," said Dr Raidal.He emphasised that his research was not just about developing a vaccine."Scientists need to better understand the nature of infectious diseases as threatening processes. The ideal would be for scientists to understand how significant the role such diseases play as a detriment to the ecological system." |
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| The circovirus (left) and its effects (right) on certain species of birds. | |
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Shane Raidal Division of Veterinary and Biomedical Sciences Telephone (08) 9360 2418 email raidal@numbat.murdoch.edu.au |