Myxomatosis

Myxomatosis: the virulence of field strains of myxoma virus in a population of wild rabbits (Oryctolagus cuniculus L.) with high resistance to myxomatosis

“…The data support the suggestion of Fenner & Ratcliffe (1965) that the interaction of virulence and resistance would maintain a moderately severe disease for a long time. The continuing evolution of virus and rabbit indicates that a climax association is at least some years away but it now seems likely that the climax association will be of a moderately severe disease with field strains of high virulence in a resistant population.…”

“…The initial mortality rate was about 99-5 %. The appearance of attenuated strains of virus and the rapid selection for resistance in the rabbit which followed reduced the mortality rate sharply (Fenner & Ratcliffe, 1965 Testing for virulence was by passage through one laboratory rabbit and intradermal inoculation of about 10 ID50 of the passaged strain into five laboratory rabbits. Each strain was graded on the basis of the response of the challenged rabbits (Fenner & Ratcliffe, 1965, pp.…”

Myxomatosis. The effect of age upon survival of wild and domestic rabbits (Oryctolagus cuniculus) with a degree of genetic resistance and unselected domestic rabbits infected with myxoma virus

“…The genetic resistance acquired by some wild rabbits since the introduction of myxoma virus into Australia in 1950 is shown by the high survival rate of the rabbits from Urana to SS; when first released standard strain had a case mortality of the order of 99 8 % (Fenner, 1959). Similar findings have been reported by Marshall & Fenner (1958) and Marshall & Douglas (1961) for rabbits from this locality.…”

“…Fenner also mentioned that there are many examples in human medicine where the age at which infection occurs has a marked bearing on the course of a disease. Studies on the effect of age upon the response of nonimmune unselected domestic rabbits to infection with myxoma virus are reviewed by Fenner & Ratcliffe (1965). A limited range of ages was covered in these studies, 1-8 weeks and 17 weeks, over which period there was an increase in survival time and recovery rate.…”

Selection for resistance to myxomatosis in domestic rabbits (Oryctolagus cuniculus)

“…In measuring the genetic resistance the many factors affecting the course of the disease such as strain of virus, dose, route of inoculation, temperature conditions etc. (see Fenner & Ratcliffe (1965) for a detailed review) must be taken into account, particularly if results from different laboratories are to be compared. A recent finding that the age at which rabbits with some genetic resistance are infected is of considerable importance to their chance of recovery (Sobey, unpublished data) adds to the above list of variables.…”