Detection by PCR of Neospora caninum in fetal tissues from spontaneous bovine abortions

The routine diagnosis of Neospora caninum abortion is based upon histopatho logic changes in fetal tissues and identification of tissue parasites by im munohistochemistry. Confirmation of N. caninum infection by immunohistochem istry has low sensitivity. In the present study, we examined the utility of PCR in detecting N, caninum infection in fetal tissues from spontaneous bo vine abortion. DNA was obtained from fresh and formalin-fixed tissues from 61 bovine fetuses submitted for abortion diagnosis, Histopathology and immu nohistochemistry determined the true status of N. caninum infection in each fetus. In formalin-fixed paraffin-embedded tissues, PCR detected N. caninu m DNA in 13 of 13 true-positive fetuses (100%) and in 1 of 16 true-negative fetuses (6%), In fresh or frozen tissues, PCR detected N, caninum DNA in 1 0 of 13 true-positive fetuses (77%) and 0 of 11 true-negative fetuses (0%), PCR also detected N, caninum DNA in 6 of 8 fetuses that had typical lesion s of N, caninum but were immunohistochemistry negative, indicating a higher sensitivity of PCR in comparison to that of immunohistochemistry. N, canin um DNA was amplified most consistently from brain tissue. PCR detection of N. caninum DNA in formalin-fixed, paraffin-embedded tissues was superior to that in fresh tissues, presumably because of the increased accuracy of sam ple selection inherent in histologic specimens.