Interactions of preimplantation mouse embryos with reovirus serotypes 1 and 3.

Mouse two-cell embryos were infected in vitro with reovirus serotypes 1/Lang and 3/Dearing, and the embryos were either implanted into pseudopregnant mice or observed in vitro for cytopathic effects. The reovirus serotypes 1/Lang and 3/Dearing differed in their capacity to kill embryos in vitro and in vivo: when embryos were infected in vitro with reovirus serotype 1/Lang and then transferred to foster mothers, pups resulted only at multiplicities of infection of a few particles per embryo. In contrast, infection of embryos with as much as 6 X 10(4) reovirus type 3 particles per embryo resulted in viable pups. In vitro, reovirus serotype 1/Lang was more virulent than serotype 3/Dearing. The infection of ovum with reovirus offers a unique model for the study of congenital infection and should yield important information concerning the molecular basis of virus virulence to maturing fetuses.