CORRELATION OF EARLY MURINE LEUKEMIA VIRUS TITER AND H-2 TYPE WITH SPONTANEOUS LEUKEMIA IN MICE OF THE BALB/c x AKR CROSS : A GENETIC ANALYSIS*

The AKR mouse strain was developed by selective breeding for a high incidence of spontaneously occurring leukemia, starting from a randombred stock in which the incidence of the disease was low to moderate (1) . The success of the breeding program strongly suggested that genetic factors play a role in the occurrence of the disease . This implication was amply confirmed in studies of crosses between highand low-leukemia mouse strains (2) . After the discovery by Gross (3) that the tissues of AKR mice yield a virus capable of transmitting the disease, it soon became clear that great variations exist from one strain of mice to another in the degree of susceptibility to the leukemogenicity of the virus . The analysis of the complex genetic control of this phenomenon has proceeded rapidly in recent years (4) .