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CSIRO virologists today corrected misinformation from an overseas veterinarian about rabbit calicivirus posing a threat to humans and other species.
The Australian scientists said that Alvin Smith of Oregon State University had confused different groups of the Calicivirus family. Some members of one group of caliciviruses can infect several species, though this is a natural ability of that virus and does not come about through mutation, as claimed by Alvin Smith.
Rabbit calicivirus belongs to another calicivirus group, and infects only one species.
According to Dr Keith Murray, Head of AAHL, "Rabbit calicivirus is found in more that forty countries around the world. There is no evidence that rabbit calicivirus has infected any animals other than European rabbits, nor is there any evidence that it affects humans."
"In a three year study at AAHL, 28 different species of animals were inoculated with large doses of the virus. None of those animals became infected with the virus or became sick from it."
Alvin Smith's press release contained several factual errors and ignores major developments over the past five years in our understanding of rabbit calicivirus.
"It is important to understand that viruses are not classified by the symptoms they cause," said Dr Harvey Westbury, a veterinary virologist at CSIRO Australian Animal Health Laboratory (AAHL).
"Viruses are grouped together and named on characteristics such as their genetic make-up and shape - not on the infections they cause. You cannot generalise about the different infections caused by caliciviruses, as Alvin Smith has done" explained Dr Westbury.
Over the years, to facilitate information exchange, scientists have developed protocols to classify viruses as they have for animals, plants and bacteria. Thousands of viruses that infect vertebrate animals are placed in 18 "families": Caliciviridae is one of those families.
The Caliciviridae can be subdivided into five groups of viruses based on their genetic make-up and strategy for replication. One of those groups contains the San Miguel Sea Lion calicivirus that can infect pigs, seals and some fish. This virus is unusual because it can infect more than one species, a peculiarity that was quickly recognised. It is a virus that CSIRO scientists have worked with at AAHL. However this virus has not mutated to infect other animals. It has always been known to have a wide host range.
"By comparison, rabbit calicivirus has a very narrow host range, as confirmed in exhaustive tests at AAHL" Dr Westbury said.
"Moreover, rabbit calicivirus is found in over forty countries spreading from Asia to Europe and northern Africa. In over ten years, it has killed millions of farmed and wild European rabbits and there has been close contact between people and diseased rabbits.
No transmission of the virus to humans, or illness related to the virus has been reported in the scientific or medical literature. "Blood tests have not revealed the presence of antibodies of the virus in humans who have had contact with the virus or with diseased rabbits," he emphasised.
The genetic material of all living things can change, or mutate, from generation to generation. Viruses are no different but this does not mean that they'll jump species. A good example is the myxoma virus which has mutated, killing fewer rabbits, but still only infects rabbits.
Dr Westbury also rebutted comments attributed to him in the Sydney Morning Herald. "Rabbit calicivirus has not changed at all since imported into Australia in 1991. The genetic make up of rabbit calicivirus strains in Europe can differ by 1 or 2%. However this difference does not mean that the biological activity of the virus has changed."
Further detailed information about RCD is available on request. Dr Keith Murray and Dr Harvey Westbury are available for interview.
Contact:
Niall Byrne
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