THE INNATE RESISTANCE OF CBA MICE TO ENDOGENOUS MURINE LEUKAEMIA VIRUS INFECTION

Summary.-The incidence of lymphomata in CBA mice is low and furthermore is unaltered by transplantation at the early blastocyst stage and being born from the lymphoma-prone AKR. The number of C-type murine leukaemia virus particles in CBA derived in this manner and milk-fostered by AKR mice in no way differs from normal CBA. The results suggest that the oncogenic Gross virus does not pass through either the transplacental or transmammary routes, or alternatively that viral replication in the CBA was in some way inhibited. Both possibilities have still to be distinguished. It is well established that the AKR strain of mice is characterized by the development of a virus-associated lym-phoma (Furth, Seibold and Rathbone, 1933). It is also well known that the CBA has a very low incidence of 'spon-taneous ' lymphomata (Murphy, 1966)