Vaccinia virus infection of cultured human first trimester trophoblast

Congenital vaccinia is a well known cause of fetal wastage. To investigate a possible mechanism of virus transmission from mother to fetus, human trophoblast isolated from 7–12 weeks placentae was challenged with vaccinia virus. First trimester trophoblast was susceptible to vaccinia virus infection in vitro, as determined by morphologic alterations, cessation of hCG synthesis, and production of progeny virus. A recombinant virus carrying HIV DNA sequences induced trophoblast expression of gp 160 and replicated to the same extent as the control wild-type strain. The results may have a bearing on the general pathogenesis of fetal infections, and serve as a reminder of the small but not negligible risk of vaccination with live virus in pregnancy.