Time course analysis of NS1 and NPM staining in DEF infected with the 977 or the Udorn virus. DEF were infected at a MOI = 3 with the 977 or the Udorn virus and fixed at the indicated time post-infection. Cells were stained with a rabbit anti-NS1 polyclonal antibody and a mouse anti-NPM monoclonal antibody, revealed with a secondary FITC-labelled anti-rabbit antibody and a secondary RhodamineX-labelled anti-mouse antibody. FITC and RhodamineX fluorescences were acquired sequentially on a confocal microscope. Asterisks point to the NPM staining pattern in non-infected cells. Arrowheads point to virus-induced changes in NPM staining pattern.