Virus distribution in tissues of the two clinically affected and euthanized acute stage-contact ducks in group 2, as determined by immunohistochemistry, virus isolation and rRT-PCR.

a Influenza nucleoprotein antigen staining was present in single cells or small foci (+) or in localized clusters with moderate (++) to abundant (+++) quantities.b Antigen found in neural tissues including neuron cell bodies, neuroglia and neuropil.c Log10 TCID50/0.1 ml of tissue homogenate.