REGULATION OF TRANSPLACENTAL VIRUS-INFECTION BY DEVELOPMENTAL AND IMMUNOLOGICAL FACTORS - STUDIES WITH LACTATE DEHYDROGENASE-ELEVATING VIRUS

Placental and fetal infections with lactate dehydrogenase-elevating vi rus (LDV) were determined by virus titration, indirect fluorescence an tibody (IFA), and in situ hybridization with cDNA probes. Experiments were designed to determine the effects of gestational age, timing of m aternal LDV infection, and immunological (antibody and cytokine) facto rs on mouse placental and fetal LDV infection. Virus infection of the placenta was detected at high levels (almost all placentas infected) w ithin 24 h post-maternal infection (p.m.i.), whereas fetal LDV infecti on was detected only at a low level by 24 h p.m.i. The percentage of f etuses becoming LDV infected progressively increased between 24 and 72 h p.m.i. When fetal infection was studied at 72 h p.m.i., earlier ges tational ages (9-11 days) were associated with fetal resistance to inf ection, whereas between 12.5 and 15 days of gestation, virus infection was detected in 50-71% of fetuses. Maternal treatment with interferon -gamma (IFN-gamma) or anti-LDV monoclonal antibodies was associated wi th reduced rates of fetal, but not placental, LDV infection. These res ults demonstrate that both developmental and immunological factors are important in the regulation of transplacental LDV infection.