RESUMEN
Persistent infection with Edmonston strain of measles virus was established in a highly susceptible clone of HEp-2 cells. The morphological and cytogenic aspects of persistent infection are presented. Carriage of measles virus in cells persistently infected is marked by important differences between standard Edmonston strain and virus stocks isolated from time to time from the carrier state. It is especially significant that cell fusion capacity decreased in amount concordant with the drop in the yield of infectious virus. Addition of UV inactivated Sendai virus, trypsin treatment or incubation at suboptimal temperatures precipitate the cytocidal effect of measles virus. Some clinical implications of reactivation of the lytic cycle in the carrier state are suggested.