Semi-quantitative assessment of swine and avian influenza antigen positive cells in the lungs.

aResults are means of two pigs; except for the Sw/B/98 intranasal group where only one pig was available.
bPercentage of bronchi and bronchioli containing viral antigen positive cells.
cImmunofluorescence score; -: negative; ±: <0.5% of epithelium positive (single cells); +: 0.5 to 1% positive; ++: >1 to 10% positive; +++: >10 to 50% positive; ++++: >50% positive.