Distribution of virus and tumour formation in ducks experimentally infected with reticuloendotheliosis virus.
The effect of reticuloendotheliosis virus (REV) was investigated in ducks. Ducks experimentally infected at 1 day and 8 weeks of age, and ducks in-contact with these, weighed less than unaffected controls. Nine of 14 ducks inoculated at 1 day old died at a mean age of 22 weeks and seven of them had tumours. REV was isolated from almost all the organs from ducks with persistent viraemia. Ducks inoculated neonatally began laying 3 weeks later than the controls and produced a significantly lower proportion (P < 0.001) of fertile eggs. Infected ducks laid thin-shelled, rough and misshapen eggs. REV was isolated from 42 of 48 albumen samples taken from these eggs and in all three batches of duck embryo fibroblast cultures prepared from them. Following infection at 1 day of age five ducks remained tolerant and most of the remaining ducks were partially tolerant to REV infection. Cell-associated and cell-free viraemia persisted until 38 weeks of age in ducks which had a serum neutralising (SN) titre < 100. Precipitating antigenaemia gave a 100% correlation with the cell-free viraemia. Ducks infected at 8 weeks of age and ducks in-contact with the ducks infected at 1 day old showed only a cell-associated transient viraemia then promptly developed SN antibodies. However, two in-contact ducks which were viraemic by 2 weeks of age remained so until the last examination at 15 weeks of age. Possible reasons for the development of antibodies to REV in uninoculated ducks are suggested.
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Department of Veterinary Clinical Studies, University of Sydney, Camden, Australia.