Fei tecnai spirit tem

To visualize a virus-like particle (VLP) in unfiltered strain RCC24, 5 μL of the culture was deposited onto glow-discharged (60 sec at 50 mA; Leica EM ACE200) formvar/carbon-coated 400 mesh copper TEM grids. Samples were stained with 2% uranyl acetate for 60 s. Excess UA was removed by gently placing a filter paper at the edge of the grids and subsequently transferred to a FEI Tecnai Spirit TEM (Thermo Fisher, USA) operating at 80 kV acceleration voltage. Images were captured with a DVC1500M camera and AMT Image Capture Engine V601 software (MA, USA). VLP diameter was measured with the AMT built-in measurement tool. All sample processing and TEM imaging were carried out in a sterile environment where no other viral experiments were done prior to the imaging.

The blocks were trimmed and sectioned into 80 nm using an ultramicrotome (Leica EM UC6). Electron micrographs were recorded using FEI Tecnai spirit TEM (Thermo Fisher Scientific) operated at 120 kV.