Evidence for the localization of porcine reproductive and respiratory syndrome virus (PRRSV) antigen and RNA in ovarian follicles in gilts

The pathogenesis of porcine reproductive and respiratory syndrome virus (PR RSV) infection in ovary was studied in sexually mature, cycling, nonsynchro nized gilts infected with the PRRSV 16244B, a virulent field strain. Previo us studies have shown that PRRSV can be isolated from ovaries and is transp lacentally passed from gilts to the fetuses. The cause of infertility follo wing PRRSV infection is not known. In this study, we identified the tropism of PRRSV in ovarian tissue from experimentally infected gilts in samples c ollected between 7 and 21 days postinfection (DPI). Tissues were collected and examined by virus isolation, in situ hybridization (ISH), immunohistoch emistry (IHC), and double labeling to identify PRRSV-infected cell types. P RRSV was isolated in ovarian follicles at 7 days DPI. The IHC and ISH indic ated that PRRSV-positive cells in ovaries were predominantly macrophages, w hich were numerous in atretic follicles. No evidence of infection and/or pe rpetuation of PRRSV in ova was observed, indicating that the female gonad i s an unlikely site of persistence. No alteration of the normal ovarian arch itecture that would support a possible role of PRRSV infection in porcine f emale infertility was observed.