Fig. 2
Electron micrographs of the HA(−), HAstop(+), and wild-type viruses. HA-MDCK cells were infected with the wild-type virus, HAstop(+) virus, or HA(−) virus, and ultrathin sections of budding virions were observed by EM. a Wild-type, b HAstop(+), and c HA(−) virions, which contain eight RNPs in the specific “1+7” configuration, bud from HA-MDCK cells. Bars, 100 nm. d–f Proportion of wild-type, HAstop(+), and HA(−) virions containing 8, 7, 6, 5, 4, 3, 2, and 1 RNPs. Approximately 100 virions embedded in 100-nm-thick ultrathin sections were counted for each virus. g, h. Digital sections of a whole HA(−) virion containing eight RNPs (g) and a whole HA(−) virion containing seven RNPs (h) from the top (upper left panel) to the bottom (lower right panel), computationally generated by electron tomography (ET). Three-dimensional models of the RNPs within the virions from the top (left) and side (right) views are shown below the digital sections panel. Bars, 50 nm. i The proportion of whole virions containing different numbers of RNPs. Approximately 10 virions each were 3D-reconstructed by ET, and the number of RNPs within each whole virion was counted
