Submitted to: Avian Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/30/2008
Publication Date: 8/31/2008
Citation: Santos, V.L.S.L., Williams, S.M., Zavala, G., Barbosa, T., Zhang, J., Cheng, S., Shivaprasad, H.L., Hafner, S., Fadly, A.M., Santos, R.L., Brown, C.C. 2008. Detection of Reticuloendotheliosis Virus by Immunohistochemistry and In Situ Hybridization in Experimentally Infected Japanese Quail Embryos and Archived Formalin-fixed and Paraffin-embedded Tumours. Avian Pathology. 37(4):451-456. Interpretive Summary: Reticuloendotheliosis virus (REV) is an avian virus that can cause cancer-like diseases and suppression of the immune system in poultry as well as in many other avian species. Although there are a number of laboratory tests that can be used for detection of virus or its antibody in affected birds, there is no practical laboratory test that can be used to specifically demonstrate the presence of virus in pathologic specimens such as tissues obtained from affected birds. In this study we tested sensitivity and specificity of two assays named immunohistochemistry (IHC) and in situ hybridization (ISH) for detection of REV in tissues obtained from experimentally inoculated quail embryos as well as from archived tissues obtained from cases previously diagnosed with REV infection. The IHC assay detects antigen (proteins) expressed by REV, whereas the ISH detects nucleic acid (genetic material) of the virus. Both assays proved to be efficient for the detection of several REV isolates in tissues obtained from experimentally infected quail embryos, but were less sensitive when applied to archived tissues. The information should be of interest to poultry disease researchers and diagnosticians, as these assays have the potential as diagnostic tools for active REV infections.
Technical Abstract: Reticuloendotheliosis virus (REV) infection can result in immunosuppression, runting syndrome, high mortality, acute reticulum cell neoplasia, or T- and/or B-cell lymphomas, in a variety of domestic and wild birds. Histopathological changes in REV infection are not sufficient to differentiate it from Avian Leukosis (AL) and Marek’s disease (MD), and currently there are no available in situ diagnostic methods for detection of active REV presence in pathologic specimens. In order to develop immunohistochemistry (IHC) and in situ hybridization (ISH) assays for detection of REV active infections, experimentally inoculated Japanese quail embryos, and archived formalin-fixed paraffin embedded tissues, from natural and experimental reticuloendotheliosis (RE) cases in chickens and turkeys, were examined. ISH and IHC assays proved to be efficient for the detection of several REV strains in Japanese quail embryos during active infection, whereas these assays were less sensitive when applied to archived tissue samples from chronically infected birds with lymphomatous disease. The diagnostic assays developed in this study have potential as diagnostic tools for detection of active REV infections.