2.6. Transmission electron microscopy (TEM) analysis
The pooled virus fraction obtained from final polishing step of 2D-AEC×SEC was transferred to a 400 mesh copper grid, left to dry without any further treatment, and negatively stained with 1% uranyl acetate solution for 1 min. The grids were viewed using a Philips FEITecnai 20 transmission electron microscopy (TEM, Royal Philips Electronics, Amsterdam) transmission electron microscope.