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Table 2 Microscopic lesions and distribution of AI nucleoprotein antigen in tissues by immunohistochemistry

From: Age is not a determinant factor in susceptibility of broilers to H5N2 clade 2.3.4.4 high pathogenicity avian influenza virus

Tissuea

Commercial broiler

SPF layer

Viral antigen stained cell types

Type of lesion

5w

8w

>30w

4wb

Trachea

+

+

−

++

Pseudostratified epithelial cells

Focal necrosis with mild lymphoplasmacytic inflammatory infiltrate

Lung

+++

+++

+

+++

Epithelium of air capillaries, mononuclear cells, endothelial cells

Moderate congestion, necrosis, and monocyte inflammatory infiltrate

Duodenum

+

−

−

na

Macrophages

NSL

Cecal tonsils

+

−

−

+

Epithelial cells of villus, cells of the muscularis externa, macrophages

Focal necrosis with lymphoplasmacytic inflammatory infiltrate

Pancreas

+++

++

+++

++

Acinar cells

Mild degeneration of individual pancreatic acinar cells

Liver

+

+

+

+

Kupffer cells, hepatocytes, macrophages

Focal necrosis with lymphoplasmacytic inflammatory infiltrate, perivascular cuffing

Kidney

++

+++

++

+

Tubular epithelial cells

Focal necrosis of tubular epithelium with lymphoplasmacytic inflammatory

Adrenal gland

++

+++

++

++

Corticotropic cells

Multifocal areas of necrosis with mononuclear inflammatory infiltrate

Spleen

+++

++

+++

++

Mononuclear cells

Multifocal areas of necrosis, hemorrhages, depletion white pulp

Thymus

+

+

+

++

Mononuclear cells

Focal necrosis, mild lymphocyte depletion, apoptotic lymphocytes

Heart

+++

+++

+++

+++

Myocardiocytes

Multifocal necrosis of myocardiocytes

Skeletal muscle

+

++

+

na

Myocytes, connective tissue, endothelial cells

NSL

Brain

+++

+++

+++

+++

Neurons, Purkinje cells, ependymal cells, glial cells

Malacia in cortex, necrosis of ependymal cells of ventricles and epithelial cells of choroid plexus, chromatolysis of Purkinje cells, lymphoplasmacytic infiltrate

Ovaries

na

na

+++

na

Tegument/interstitial tissue, granulocytes

Focal necrosis with lymphoplasmacytic inflammatory infiltrate

Infundibulum

na

na

+

na

Ciliated epithelial cells

NSL

  1. 4w: 4-week old SPF White Leghorn layers, 5w: 5-week old broilers, 8w: 8-week old broilers, na: not applicable, NSL: no significant lesions.
  2. aTissues not present appeared overtly normal on histopathological analysis and did not show positive immunohistochemical staining.
  3. bFor comparative purposes, data from DeJesus et al. [8] on 4-week old SPF White Leghorn chickens challenged with Tk/MN/15 virus have been added.
  4. − = no positive cells; + = single positive cells; ++ = scattered groups of positive cells; +++ = widespread positivity.