Studies in the epidemiology of infectious myxomatosis of rabbits: V. Changes in the innate resistance of Australian Wild rabbits exposed to myxomatosis

Abstract

Annually for 4 years groups of young Australian wild rabbits have been captured during non-epizootic periods from areas in which myxomatosis has occurred during the previous summer. The intensity of the preceding epizootic was measured by testing a sample of survivors for antibody. The captured young rabbits were raised in the laboratory until they were about 4 months old and then inoculated intradermally with small doses of the slightly attenuated myxoma virus strain Aust/Corowa/12–52/2 (KM 13), all samples of virus being derived from the same batch which has been stored at -70°C.The results show there is a significant negative correlation between the mortality rate and the degree of exposure to myxomatosis of the forbears of the tested animals. Passive and active immunization have been excluded and this result is ascribed to increased genetic resistance.We are greatly indebted to Mr. F. N. Ratcliffe, Officer in Charge of the Wildlife Survey Section of the Commonwealth Scientific and Industrial Organization, and to his officers, especially Messrs W. E. Poole, K. E. Myers, G. Douglas, B. V. Fennessy, H. Frith and K. Keith for their invaluable assistance in collecting rabbits and serum samples.We have had valuable discussions with Dr W. R. Sobey, Dr P. J. Claringbold and Dr G. S. Watson on genetical and statistical aspects of the problems under study.

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

“…Similar findings have been reported by Marshall & Fenner (1958) and Marshall & Douglas (1961) for rabbits from this locality. The rabbits from Seaspray and Natimuk in Victoria showed an elevated XS.T.…”

Long‐lasting immunity by early infection of maternal‐antibody‐protected infants

“…Historically, mortality of smallpox was allegedly 40-80%, but subsequently dropped to much lower levels. This could be due to uncharacterized ''attenuation'' of the virus, or increased resistance of the host [12]. More likely in our view, the here formally documented attenuation by maternal antibodies under active epidemiological conditions is probably quicker and generally more important.…”

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

“…A build up of innate resistance to myxomatosis in the wild rabbit population after the release and spread of myxoma virus in Australia in 1950 was both predicted and found (Fenner, 1953;Marshall & Fenner, 1958;Marshall & Douglas, 1961). A programme of selection for resistance to myxoma virus in domestic rabbits was begun in this laboratory in 1954.…”