PREGNANT FERRET AS A MODEL FOR STUDYING CONGENITAL EFFECTS OF INFLUENZA-VIRUS INFECTION INUTERO - INFECTION OF FETAL TISSUES IN ORGAN-CULTURE AND INVIVO

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 58  (2) , 113-123
Abstract
Organ cultures of ferret fetal tissues showed a similar pattern of susceptibility to influenza virus to that already observed for human fetal tissues; respiratory, alimentary and urogenital tissues supported the replication of influenza virus but nervous and lymphopoietic tissues (those which, in man, were associated with fetal or postnatal abnormalities) were insusceptible. In contrast to corresponding human tissues, ferret fetal placenta and amnion readily supported viral replication although both human and ferret umbilical cord were susceptible. In limited experiments, neither the membranes nor the susceptible fetal tissues were infected after intranasal inoculation of pregnant ferrets of various gestational ages. After intracardial inoculation of pregnant ferrets with higher titer virus (approximately 109 EBID50 [average total virus content]) virus was isolated from both fetal membranes and fetuses. The membranes were infected at early, middle and late gestation, but virus appeared to cross the placental barrier to infect fetal tissues only in late gestation. At this stage virus was isolated not only from those fetal tissues (respiratory, alimentary and urogenital) susceptible in organ culture, but also in small amounts from tissues which were insusceptible in organ culture (heart, lymphopoietic and nervous tissue). Virus was also isolated from fetal membranes and fetuses of late gestation ferrets following intracardial inoculation with a 100-fold lower dose of virus which, unlike the higher dose, did not induce a maternal febrile response. The pregnant ferret was a suitable model for investigating the effects on development of fetal infection with influenza virus but it may have disadvantages with regard to the nature and strength of the placental barrier.