Histopathologic and immunohistochemical findings in the placentas and fetuses of domestic swine naturally infected with biovar 2.

Porcine brucellosis, which is caused by biovar (bv) 2, is a re-emerging disease that causes reproductive problems in pigs in Europe. The pathogenesis and lesions of intrauterine infection are poorly characterized; characterization could facilitate the diagnosis and investigation of porcine brucellosis. We collected samples of placentas and fetuses for histologic and microbiologic studies during an outbreak of abortions on a pig-breeding farm in Spain. was cultured from the vaginal swabs obtained from sows that had aborted, some placentas, and fetal tissues (spleen, liver, lung, gastric content); molecular testing confirmed bv 2 infection. Histologically, there was necrotizing and hemorrhagic placentitis; suppurative hepatitis; lymphoid depletion and sinusoidal histiocytosis in the spleen, lymph nodes, and thymus; and bronchointerstitial pneumonia. Hemorrhages were observed in the umbilical cord, heart, kidneys, and brain. We detected by immunohistochemistry (IHC) in all of the placentas and fetal organs studied, specifically in the trophoblasts of the chorionic epithelium, in the cytoplasm of macrophages in the chorionic stroma, and extracellularly in necrotic debris. Furthermore, we assessed the lymphocyte population in the placentas through the use of IHC (anti-CD3, anti- antibodies), revealing that the lymphocytic response was composed of T cells but not B cells.