High density and specificity of 5nm-Ni-NTA-nanogold labeling on mitochondria from FHV-His–ΔB1 infected S2 cells Tomogram from figure 6B, right represented as Z-stack series. The high-density of 5nm-Ni-NTA-nanogold labeling is apparent in the tomogram with spherules decorated with nanogold throughout the mitochondria. Additionally, the regions highlighted by white arrow on the mitochondria is devoid of spherules and nanogold, whereas, the region shown by yellow arrow is densely labeled, which indicates high specificity of nanogold labeling.