Evidence for the existence of latent myxoma virus in rabbits (Oryctolaqus cuniculus (L.) )
Williams, R.T.; Dunsmore, J.D.; Parer, I.
Nature 238(5359): 99-101
1972
ISSN/ISBN: 0028-0836 PMID: 4557791 Document Number: 53888
Of 11 cases of myxomatosis in a rabbit enclosure in December, 1969, in Canberra, seven were in adult animals which had previously shown circulating antibodies to myxoma virus. The animals were under stress at the time, having just ceased breeding at the onset of summer and were overcrowded. Twenty 'immune' rabbits that survived this outbreak were caged and subjected to two periods of heat stress (23.9 deg and 26.7 deg C) and one of cold stress (1.7 deg C); daily injections of ACTH were given during the first period of heat stress. One animal developed generalized myxomatosis (during the first period of heat stress) and yielded virulent virus. Several other animals developed reddening and swelling of the lids of one eye, but did not yield the virus from the purulent ocular discharge. In another experiment, a rabbit that had survived artificial challenge with a field strain of myxoma virus, and formed specific antibodies, developed myxomatosis 9 months later, during an outbreak, and yielded virulent virus from eye discharge. It is concluded that many, if not most epidemics in Australia are initiated by rabbits in which latent myxoma virus has been reactivated.