A GENETICALLY modified virus that can spread from rabbit to rabbit for one
generation and immunise them against two major diseases has been created in
Spain. Its development has caused unease in countries such as Australia, where
rabbits are serious pests and the diseases play a key role in limiting their
numbers.
鈥淚f I was a farmer I would be concerned,鈥� says David Cowan of Britain鈥檚
Central Science Laboratory in York. 鈥淩abbits cause up to 拢100 million
worth of damage in the UK per year.鈥�
The vaccine, developed by Juan Torres and his colleagues at the Centre for
Investigation into Animal Health in Madrid, is a weakened form of the myxoma
virus that causes myxomatosis. A protein from the virus that causes rabbit
haemorrhagic disease (RHD) has also been added, so animals become immune to RHD
too.
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According to the researchers, the virus cannot replicate properly, so while
the first rabbits that become infected can pass it on, the virus should not be
transferred a second time. They say tests show that the virus is safe, and are
now running a field trial involving 300 rabbits on a small island
(Vaccine, vol 19, p 174).
But others are not persuaded. 鈥淭hey are basically creating a new disease,鈥�
says Cowan. 鈥淚鈥檇 want to be very convinced about its safety and species
specificity before it was released.鈥�
Brian Cooke of CSIRO, Australia鈥檚 national research organisation, worries
that the virus might be deliberately released in Australia. In the field, he
says, it might behave differently or regain the ability to replicate.
鈥淭his self-propagating vaccine is not a development that sits easily with
rabbit control in Australia,鈥� he says. 鈥淢yxomatosis and RHD, although repugnant
from an animal welfare perspective, nevertheless have great benefits for
agriculture. Both diseases are vitally important for rabbit control in
础耻蝉迟谤补濒颈补.鈥�
Torres says Spain needs the vaccine because rabbit numbers there are low.
鈥淢yxomatosis and RHD are endangering not only the survival of the rabbit, but
also their natural predators,鈥� Torres says.
But Cooke claims that the work 鈥渉as been mainly done at the instigation of
hunting organisations鈥�. Torres admits the project is partly funded by the
Spanish Federation of Hunters, but says hunters鈥� cooperation is vital. 鈥淗unters
have the ability to capture and vaccinate many animals.鈥�
Another genetically modified virus being developed by Cooke kills rabbits or
makes them infertile (91av, 7 October 1995, p 8). It can be
transmitted many times, and Torres is worried that it might reach Spain. 鈥淚t
would be very dangerous for the rabbit population here,鈥� he says. While the
Spanish and Australian researchers are cooperating, Cooke admits they have
鈥渃ompletely opposed aims鈥�.
Once any virus is released, it won鈥檛 necessarily respect national or even
continental borders. 鈥淵ou don鈥檛 want to release something that you have no
control over,鈥� says Cowan.
