Many of the lesions of Newcastle disease occur because the virus infects and damages:

• A. Lymphoid Tissues And Neurons
• B. Respiratory Epithelium
• C. Neurons Only
• D. Gastrointestinal Epithelial Cells

Answer: (A)

Newcastle disease virus is both lymphotropic and neurotropic. After infection, it spreads throughout the body and replicates in lymphoid organs such as the bursa of Fabricius, thymus, and spleen, causing necrosis and depletion of immune cells. This immunosuppression and systemic involvement account for many of the disease’s lesions. The virus also invades the central nervous system, causing encephalitis and neuronal damage that leads to neurologic signs and brain lesions. While infection of respiratory and GI epithelia occurs and contributes to disease, the most characteristic and widespread lesions arise from damage to lymphoid tissues and neurons, making the option describing lymphoid tissues and neurons the best choice.