Teratogenic effects of Colorado tick fever virus in mice.

The teratogenic effects in mice of Colorado tick fever (CTF) virus, a human pathogen, were demonstrated. Various routes of inoculation, gestational periods, and dosages of virus were studied. The incidence of stillbirth and neonatal death increased significantly after inoculation of pregnant mice with CTF virus. CTF virus crossed the placenta and replicated to high titers in the placental and fetal tissues. Mice that survived the first six weeks of life had neutralizing antibody to CTF virus. Neutralization tests, in which pregnant mice were inoculated with both CTF virus and specific antiserum to CTF virus, validated the teratogenic effects of CTF virus in mice.