Infectious bronchitis corona virus establishes productive infection in avian macrophages interfering with selected antimicrobial functions
Six days old chickens were infected intra-tracheally with IBV M41 (n = 5) and Conn A5968 (n = 5) strains (2.75×104 EID50 per bird) with uninfected controls (n = 4) and lung and tracheal tissues were collected in OCT and 10% formal saline at 4 dpi. Five μm frozen sections were immunostained for demonstrating IBV antigen and paraffin embedded sections were H&E stained. IBV N antigen in the tracheal and lung sections were stained using DyLight® 550 fluorescent (arrow heads). In the IBV infected trachea, complete loss of cilia (a) and thickening of the mucosa with inflammatory cell infiltration can be seen compared to the control trachea. In the IBV infected lungs, inflammation leading to reduced air exchange areas and reduced lumen of parabronchi are visible. Also, the difference of mucosal thickening in the infected and uninfected trachea is shown (d). a = cilia, b = tracheal cartilage, c = tracheal lumen, d = mucosal layer, e = parabronchial lumen and f = interparabronchial septum.