document: Transmission electron microscopy (TEM). Five microlitres of VLP-based samples were pipetted onto Formvar-coated copper mesh grids (400 mesh, Ted Pella, Redding, CA, USA) for 5 min, followed by exposure to 8 µL of a solution of uranyl acetate (15 mg/mL in DI-H2O) for 2 min as a negative stain. Excess stain was then removed, and the grids could dry in air for 10 min.