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Vet Res. 2016 Aug 5;47(1):76. doi: 10.1186/s13567-016-0364-7.

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

Author information

1
Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada. predrag.novakovic@usask.ca.
2
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
3
University Clinic for Swine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria.
4
Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
5
Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.

Abstract

Several routes of porcine reproductive and respiratory virus PRRSV transmission across the porcine diffuse epitheliochorial placentation have been proposed, but none have been proven. 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 infection 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 dichotomous responses in endometrium and placenta for both CD163 and CD169 cells.

PMID:
27494990
PMCID:
PMC4974782
DOI:
10.1186/s13567-016-0364-7
[Indexed for MEDLINE]
Free PMC Article

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