Abstract
Summary
Females of 3 different C3H strains, low-leukemic C3Hf/lw and C3Hf/Gs and high-leukemic C3Hf/Fg, were found capable of transmitting MLV to successive generations of offspring. The most effective mechanism of transmission was through mother's milk. “Infected'females transmitted MLV whether or not they eventually became leukemic. Reciprocal foster-nursing experiments revealed that transmission of virus could occur from mother to offspring during the prenatal period. A low frequency, later age at death from the disease and sporadic occurrence were observed in litters born to “infected'females but foster-nursed upon normal, non-inoculated mothers of the C3H strains. In contrast, however, no leukemias have appeared to date in those offspring born to “infected'mothers but foster-nursed upon C57Bl/Ka mothers. Stable high-leukemic and low-leukemic lines of different C3H strains have been established simply through foster-nursings. Foster-nursing upon low-leukemic mothers combined with thymectomy through successive generations of high-leukemic AKR strain mice did not influence the frequency of or mean age at death from lymphocytic neoplasms. The pattern of transmission of leukemic potentialities in AKR, as well as in other established high-leukemic strains, viz., C58, F, and C3Hf/Fg, is of a chromosomal type in contrast to the extrachromosomal pattern of transmission of MLV and presumably of Gross Passage A virus. Further data are given concerning the inability of “infected'males to transmit MLV.
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