Influence of dietary phenylalanine deficiency on the mammary tumor virus activity in C3H mice.

This paper reports the blood-borne mammary tumor virus activity of C3H/Crgl female virgin mice previously fed phenylalanine-deficient diets. Whole blood was removed from three groups of female virgin C3H/Crgl mice previously fed semipurified diets containing, respectively, 0.075, 0.120, and 0.300% phenylalanine for 8 months. The blood was twice diluted and 0.3 ml was injected into each C3HfBALB/cCrgl test mouse which was then subjected to the standard noduligenesis test for viral activity. The mammary glands of each test mouse were stimulated for 12 to 13 weeks by two pituitary isografts implanted under the kidney capsule. The percentage of phenylalanine in diet of donor mice/% of donor mice bearing spontaneous hyperplastic alveolar nodules (HAN)/% of test mice bearing induced HAN are: 0.075/0/40, 0.120/16/37, and 0.300/100/39. Negative control test mice that did not receive blood but were subjected to the noduligenesis test had 6.7% incidence of HAN. The formation of spontaneous HAN in the original donor mice was completely inhibited when phenylalanine in the diet was lowered to 0.075%. However, the data reported herein show that such inhibition was not due to an absence of blood-borne mammary tumor virus. Although the relative amounts of mammary tumor virus in the donor mice was not tested, the uniformity of response of the test mice suggests that large differences would not be expected.