title: Pathologic Evaluation of Type 2 Porcine Reproductive and Respiratory Syndrome Virus Infection at the Maternal-Fetal Interface of Late Gestation Pregnant Gilts.
abstract: The pathogenesis of fetal death caused by porcine reproductive and respiratory syndrome virus (PRRSV) remains unclear. The objective of this study was to improve our understanding of the pathogenesis by assessing potential relationships between specific histopathological lesions and PRRSV RNA concentration in the fetuses and the maternal-fetal interface. Pregnant gilts were inoculated with PRRSV (n = 114) or sham inoculated (n = 19) at 85±1 days of gestation. Dams and their litters were humanely euthanized and necropsied 21 days later. PRRSV RNA concentration was measured by qRT-PCR in the maternal-fetal interface and fetal thymus (n = 1391). Presence of fetal lesions was positively related to PRRSV RNA concentration in the maternal-fetal interface and fetal thymus (P<0.05 for both), but not to the distribution or severity of vasculitis, or the severity of endometrial inflammation. The presence of fetal and umbilical lesions was associated with greater odds of meconium staining (P<0.05 for both). The distribution and severity of vasculitis in endometrium were not significantly related to PRRSV RNA concentration in maternal-fetal interface or fetal thymus. Endometrial inflammation severity was positively related to distribution and severity of vasculitis in endometrium (P<0.001 for both). Conclusions from this study suggest that type 2 PRRSV infection in pregnant gilts induces significant histopathological lesions at maternal-fetal interface, but they are not associated with presence of PRRSV in the maternal-fetal interface at 21 days post infection. Conversely, fetal pathological lesions are associated with presence of PRRSV in the maternal-fetal interface and fetal thymus, and meconium staining is significantly associated with the presence of both fetal and umbilical lesions observed 21 days post infection.
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Predrag
authors.initials: P
authors.lastname: Novakovic
authors.affiliation: Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: John C S
authors.initials: JC
authors.lastname: Harding
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Ahmad N
authors.initials: AN
authors.lastname: Al-Dissi
authors.affiliation: Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.|University Clinic for Swine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ladinig
authors.affiliation: Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Detmer
mesh_terms: D000818:Animals; D004715:Endometriosis / Q000378:metabolism / Q000473:pathology / Q000821:virology; D005260:Female; D005333:Fetus / Q000196:embryology / Q000473:pathology / Q000821:virology; D010920:Placenta / Q000378:metabolism* / Q000473:pathology / Q000821:virology*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000378:metabolism* / Q000473:pathology; D019316:Porcine respiratory and reproductive syndrome virus / Q000378:metabolism*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000378:metabolism* / Q000473:pathology / Q000821:virology*; D012367:RNA, Viral / Q000378:metabolism*; D013552:Swine / Q000378:metabolism / Q000821:virology; D013950:Thymus Gland / Q000196:embryology / Q000473:pathology / Q000821:virology; D014657:Vasculitis / Q000378:metabolism / Q000473:pathology / Q000821:virology
chemical_list: D012367:RNA, Viral