THF-CAR cells were infected with AdV-MAYV with a MOI = 100 PFU/cell. Media was harvested 72 hpi and cell debris was pelleted at 2,514 x g in a tabletop centrifuge for 10 minutes. Clarified media was then 0.22 μM filtered, and 10% Sorbitol was underlaid. Tubes were spun at 110,527 x g for 2 h. Supernatant was poured off and pellets were resuspended in 250 μl of PBS and 0.22 μM filtered. Resuspended samples were brought to a final volume of 1 ml in 15% trehalose [42], and a 50 μl sample was fixed in 4% PFA for 30 minutes and frozen at -80°C. Samples were stained with uranyl acetate and EM images were taken by the OHSU Multiscale Microscopy Core on a Krios G4 Cryo-TEM.