Kodevirion

virions with detectable FSL constructs.^[5][6]

radioactive iodine (FSL-125I). FSL-FLRO4 could be shown to label virions in a dose dependent manner and could be visualized by flow cytometry either directly, or indirectly if the virion had bound to the cell or fused with the cell membrane.^[6] FSLs do not appear to significantly affect the virions infectivity or their ability to bind target cells, probably because they integrate into the membrane without exposing the virion to chemical agents or covalent modification^{[citation needed}