Table 3. Summary of Virus Distribution in Tissues of the HPAIV H5N1-Infected Chickens IHC scoring system.

(-) no viral antigen detected; (+) sporadic; (++) common; (+++) widespread.

Tissue	IHC Score	Type of Cells Expressing Virus Antigen
Trachea	+++	Endothelial cells and epithelial cells
Lung	+	Macrophages, Lymphocytes
Brain	+++	Endothelial cells, neurons and glial cells especially in perkinji cell layer
Spleen	+	Lymphocytes, Endothelial mononuclear cells
Bursa	+	Lymphocytes inside Follicular layer, endothelial cells
Pancreas	+++	Pancreatic acinar epithelium, macrophages and endothelial cells
Proventriculus	+	Glandular epithelium
Testis	++	Inter seminephrous space, intra seminephrous tubules sticking to sperms

IHC scoring system: (-) no viral antigen detected; (+) sporadic; (++) common; (+++) widespread.