FIG 1.

Histopathology of the brains in NDV-infected chickens. (A) Four-week-old SPF chickens were infected with virulent F48E9, avirulent LaSota (10⁵ PFU/100 μl/chicken), and PBS control (100 μl/chicken) via the intraocular-nasal routes. The brain samples were collected for HE and IHC analyses with anti-F48E9 mouse PAb (1:500) and anti-LaSota mouse PAb (1:500) at 5 dpi. The black arrows indicate vascular cuffing lesions in the cerebrum. Bars, 50 μm. (B) The viral titers were titrated in 9- to 11-day-old SPF embryonated chicken eggs. The 50% egg infective dose (EID₅₀) values were calculated using the Reed-Muench method. (C) The relative mRNA expression of viral NP genes in F48E9- and LaSota-infected chicken brains, normalized to that of 28S rRNA, was determined by RT-qPCR. The results are presented as the means ± SDs from three independent experiments.