Expression of chicken interleukin-2 by a highly virulent strain of Newcastle disease virus leads to decreased systemic viral load but does not significantly affect mortality in chickens

Table 2 Intensity of lesions (HE) and immunohistochemical staining (IHC) for NDV nucleoprotein in selected organs by days post infection (dpi). BHI-infected group did not present any lesions

Histological grading
Eyelid: + presence of severe edema, which expands the submucosa; ++ multifocal inflammatory infiltrate; +++ coalescing / diffuse inflammatory infiltrate
Thymus: lymphoid depletion and apoptosis / necrosis of the thymic cortex, + < 20 %; ++ 26 to 50 %; +++ > 50 %
Cecal tonsil and Bursa: lymphoid depletion / necrosis, + < 20 %, ++ 26 to 50 %; +++ > 50 %
Spleen: prominent macrophages surrounding the penicillary arteries, +; confluent Schweigger-Seidel sheaths, ++; lymphoid depletion and apoptosis +++; diffuse necrosis and fibrin exudation ++++
Brain: vascular reactivity, +; perivascular mononuclear cuffing ++
Immunohistochemical grading
- = no IHC signal present
+ = rare cells in the section are positive on IHC
++ = positive cells seen, <50 % of all high power fields (HPF)
+++ = positive signal seen in > 50 % of HPF

ISSN: 1743-422X