Figure 1. Experimental design and model.

(A) The medium from primary human trophoblasts (PHT cells) was collected after 48-72 hours, and transferred to nontrophoblast recipient cells 24 h prior to infection. The level of pathogen infection in recipient cells was compared to cells exposed to control medium. See Methods for details. (B) A proposed model for the protective effect of exosome-packaged C19MC miRNAs. Exosomes are transferred from the placenta into the maternal circulation (M), and perhaps into the fetal circulation (F), where they may attenuate viral infection.