Comparison of pathology-based techniques for detection of viscerotropic velogenic Newcastle disease virus in chickens.

Two pathology-based techniques, immunohistochemistry and riboprobe in-situ hybridization, were applied to formalin-fixed, paraffin wax-embedded tissues from chickens infected with three different isolates of velogenic viscerotropic Newcastle disease virus (VVNDV). With the immunohistochemical method, viral protein was consistently detectable in the spleen and caecum at the terminal phase of the infection. With in-situ hybridization, viral nucleic acid was consistently detected in the eyelid, spleen and caecum in both the acute and terminal phases. Hybridization with anti-sense probe to detect viral mRNA was often more intense than hybridization with sense probe to detect viral genomic RNA.