Relationships of CD163 and CD169 positive cell numbers in the endometrium and fetal placenta with type 2 PRRSV RNA concentration in fetal thymus

The objectives of this study were to investigate associations between numbers of CD163 and CD169 positive macrophages, cathepsin positive areolae, and type 2 PRRSV load at the maternal –fetal interface in order to examine important factors related to transplacental infection. On gestation day 85 ± 1, naïve pregnant gilts were inoculated with PRRSV (n = 114) or were sham inoculated (n = 19). At 21 days post-inoculation (dpi), dams and their litters were humanely euthanized and necropsied. Samples of the maternal–fetal interface (uterus with fully attached placenta) and fetal thymus were collected for analysis by RT-qPCR to quantify PRRSV RNA concentration. The corresponding paraffin-embedded uterine tissue sections were subjected to immunohistochemistry for PRRSV nucleocapsid N protein, CD163, CD169, and cathepsin. Our findings confirm significant increases in the numbers of PRRSV, CD163 and CD169 positive cells at the maternal–fetal interface during type 2 PRRSV in fection in pregnant gilts. PRRSV load in fetal thymus was positively related to CD163+ cell count in endometrium and negatively related to CD163+ cell count in placenta, but unrelated to CD169 counts or cathepsin positive areolae. The endometrium:placenta ratio of CD163 cells, and to a lesser extent CD169 cells, was significantly associated with an increase fetal viral load in thymus. These findings suggest a more important role for CD163+ cells following trans-placental PRRSV infection, but dichotom...
Source: Veterinary Research - Category: Veterinary Research Source Type: research