Abstract: AIM: To study the possibility and conditions of transplacental infection of coxsackievirus B3(CVB₃) from pregnant mice to their fetuses and newborns. METHODS: Coxsackievirus B₃ strain causing balb/c mice myocardial injury ( CVB_3m ) was inoculated with 10⁵ TCID₅₀ in dose into the mother mice at 6-7 days (early gestation), 9-10 days ( middle gestation) and 17-18 days ( late gestation) of gestation, in contrast with non-pregnant mice. Some placentas and fetuses were removed by caesarean section before mothers partusing; some mothers and their babies were sacrificed after parturition, and virus isolation, serological and pathological tests were performed. RESULTS: Viramiae was observed in mother mice of late-gestation inoculated with CVB_3m at a fit amount on the second day after inoculation, while no newtralizing antibody to CVB_3m was detected in blood. The virus was isolated from cardiac muscles of inoculated mother mice in different gestation and the controls. The virus was also isolated from some placentas and fetuses, and both sera and cardiac muscles of infants in the late gestation ( virus titer were all 10 ^-2—10^-3). On d 7 of inoculating virus, pregnant and non-pregnant mice titers of neutralizing antibody to CVB_3m in sera were all between 1 ∶160 and 1 ∶320. Under the electromicroscopy, some cardiac muscle cells of mother or infant mice appeared with morphological changes and little hollow bubbles occured in cytoplasm. The fibers broke off, and the bright and dark belts became indistinct. CONCLUSION: The amimal model, intraplacental passage of CVB₃from pregnant mother in late gestation to fetus in mice, is a benefitial tool to study enterovirus diseases in human perinatal period.

Key words: coxackievirus B₃, transplacental infection, viramiae