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Figure 2 | Veterinary Research

Figure 2

From: Pathogenesis and prevention of placental and transplacental porcine reproductive and respiratory syndrome virus infection

Figure 2

Events during PRRSV infection in the maternal-fetal interface in sows intranasally inoculated at 90 days of gestation. 1. Maternal blood vessel. 2. Endometrial connective tissue. 3. Uterine epithelium. 4. Trophoblast. 5. Fetal placental mesenchyme. 6. Fetal blood vessel. (A) During viremia PRRSV attaches and probably enters and replicates in susceptible monocytes adhering to the endothelial cells of the endometrial vessels. Extravasation of the PRRSV-bearing monocytes from maternal blood to the endometrium. (B) PRRSV replicates in the endometrial macrophages. PRRSV causes apoptosis in infected and surrounding cells during replication within the endometrium. PRRSV crosses the uterine epithelium and trophoblast, most probably in association with maternal macrophages. (C) Focal, highly efficient PRRSV replication in the fetal placental macrophages. PRRSV reaches fetal internal organs most likely through the umbilical circulation. PRRSV causes apoptosis in infected and surrounding cells during replication in the placenta. (D) Maternal immunity (most probably CD8+ endometrial NK cells) suppresses PRRSV replication within the endometrium. Focal, highly efficient PRRSV replication in the placenta. (E) Focal detachment of the trophoblast from the uterine epithelium and focal degeneration of the placenta, at the places of virus replication and probably in the adjacent sites. (F) Multifocal degeneration and finally full degeneration of the placenta, at the places of virus replication, and probably in the adjacent sites.

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