All mice of C57BL/St, C3H/St, BALB/cSt, NZB/Scr, and NZW/Lac strains developed high levels of p30 antigenemia after inoculation at birth with murine leukemia virus (Scripps). Transmission of virus from neonatally infected parents to their progeny for three successive generations, as evidenced by development of p30 antigenemia, varied among the five strains. Through the three generations, 100% transmission occurred in C3H/St and BALB/cSt mice, 50 to 61% transmission occurred in C57BL/St and NZW/Lac mice, and 11% transmission to the first generation, with no subsequent transmission, occurred in the NZB/Scr mice.
Transmission appeared to occur readily via the milk in all strains. Intrauterine events also played a role with evidence of some viral transfer prior to birth in the C3H/St strain or, conversely, the development of resistance to infection prior to birth in C57BL/St mice. The occurrence of litters from infected parents containing both normal offsprping and offspring with elevated p30 appeared to be the result of variable resistance in the intact offspring, perhaps as a result of intrauterine events, and not related to cellular resistance observable in tissue culture or to dominant genetic factors.
This research was supported by USPHS Grant NOI-CP-43375 and NIH-AI-07007, Elsa U. Pardee Foundation. This is Publication 999.