Animal models for perinatal transmission of pathogenic viruses.

In earlier work, mouse models have been used to demonstrate the efficacy and lack of toxicity of transplacental and perinatal AZT therapy. These practical small animal models can be useful for evaluating antiviral drugs aimed at common retroviral functions only, since Type C MuLVs are used. A primate model for fetal infection with an immunosuppressive lentivirus, SIV, has been established using ultrasound-guided inoculation of the amniotic fluid. The infection rate was 86% overall and 100% if the fetal SIV exposure occurred at least 19 days before delivery. The suspected major route of vertical HIV-1 transmission, that is, virus entry through fetal mucous membranes or skin, is replicated by our approach. The high fetal infection rate will allow studies of SIV pathogenesis during various stages of fetal development. This model should be well suited to development and evaluation of therapeutic strategies for preventing fetal infection.