Vertical transmission of feline immunodeficiency virus.

We studied vertical transmission of feline immunodeficiency virus (FIV) to determine whether it might provide a model with which to study intervention strategies for mother-to-offspring transmission of human immunodeficiency virus (HIV). We found that pregnant cats acutely infected with FIV (FIV-CSU-2771) transmitted the virus to their offspring via both prenatal and postnatal routes. In utero transmission led to several pathogenic consequences including arrested fetal development, abortion, stillbirth, subnormal birth weights, and birth of viable, virus-infected, and asymptomatic but T cell-deficient kittens. Postnatal milk-borne FIV transmission was demonstrated by the presence of cell-free and cell-associated virus in colostrum and milk and through a foster-nursing experiment. The potential for intrapartum FIV transmission was documented by frequent virus isolation from vaginal wash cells in both the pre- and postpartum periods. FIV transmission was efficient during acute maternal infection, leading to an overall infection rate of 70%. We conclude that FIV vertical transmission may be a useful model with which to evaluate intervention strategies for HIV transmission from mother to child.