Immunohistochemical and immunocytochemical findings associated with Marek's disease virus in naturally infected laying hens

We compared immunohistochemical (IHC) staining of tissue sections of liver, kidney, spleen, lung, proventriculus, sciatic nerve, bursa of Fabricius, brain, heart, intestine and skin; immunocytochemical (ICC) staining of peripheral blood samples and touch preparations of liver, spleen and kidney of laying hens naturally infected with Marek's disease (MD) virus. We used one hundred and fifty 5-17-week-old commercial hens. IHC and ICC staining were performed using polymer-based techniques. IHC staining exhibited mostly free immunopositive reactions in tumor cells and in the cytoplasm of the parenchymal cells of liver, kidney, spleen and bursa of Fabricius. In the sciatic nerve, severe reactions were observed in the cytoplasm of plasma and MD cells in the lymphoproliferative areas. Pronounced staining was found in the lymphoid cells in the medulla of intrafollicular regions in the bursa of Fabricius. Although immunostaining was observed in the liver and spleen touch preparations, there was no staining in the kidneys and peripheral blood cell samples. The presence of virus in the tissue and peripheral blood samples and in touch preparations was compared immunohistochemically and immunocytochemically. IHC and ICC techniques were helpful for diagnosis of MD. Peripheral blood samples are inappropriate for field conditions and natural infections.