Abstract
Comparative data are presented on the intra- and extracellular concentrations of blood ribonuclease in two different strains of mice; one rabies-susceptible, the other rabies-refractory. The coincidence of finding a higher extracellular level of the enzyme in the rabies-refractory group is discussed in its possible relationship to mechanisms of host susceptibility and resistance to virulent rabies virus. The probable genetic basis for the differences in enzyme localization is also discussed.