RELATIONSHIP BETWEEN SURVIVAL RATE AND SURVIVAL-TIME OF RABBITS, ORYCTOLAGUS-CUNICULUS (L), CHALLENGED WITH MYXOMA VIRUS

The mean survival times of small groups of rabbits challenged with myx oma virus have been used to estimate survival rates and to allocate vi rulence grades to field strains of myxoma virus. The slope of the regr ession Line relating survival percentage to mean survival time in days was shown to be less steep than has been previously estimated. This o verestimation of the regression slope has, in the past, resulted in mo st field strains of myxoma virus being allocated to the Grade III leve l of virulence when allocation to Grade I would have been more appropr iate.