Transmission of auto-immune haemolytic anaemia and murine leukaemia virus in F1 (BALB/c X NZB) hybrid mice derived by ovum transplantation.

F1(BALB/c X NZB)hybrid progeny derived by ovum transplantation were used to study the transmission of auto-immune haemolytic anaemia and murine leukaemia virus (MuLV) by male New Zealand black (NZB) mice. Fertilized ova, collected from the normal BALB/c partners 3 1/2 days after mating, were transferred to other, surrogate, BALB/c mothers, which then carried, delivered, and reared the hybrid young. This technical manoeuvre effectively closed the congenital transplacental route theoretically available to any infectious MuLV originating from the NZB father. Nevertheless, such progeny developed exactly the same profile of auto-immune haemolytic disease and the same range of diverse malignancies as their normally-derived F1(BALB/c X NZB) counterparts, and they carried type C MuLV particles readily detectable by electronmicroscopy. We concluded, therefore, that both the auto-immunity and virus were transmitted before placentation, presumably by the NZB male at fertilization, and probably as genetic information.