The present invention relates to the use of rotavirus particles for displaying a heterologous protein, alone or in complex with another molecule. The invention further relates to methods that employ these modified rotavirus particles to rapidly determine the structure of the heterologous protein or the complex using cryo-electron microscopy (cryo-EM). The invention also relates to a method of immunizing a patient, wherein said method comprises administering to the patient the modified rotavirus particles of the invention.