[Electron microscopy study of the nucleocapsid structure of the measles virus isolated from cell cultures with primary and chronic infections].

Electron microscopic examination of isolated intracellular measles virus nucleocapsids (NC) revealed a relationship between their structure, cell system, and the type of infection. Acute virus infection of Vero or Japanese quail embryo cells gave rise to the formation of linear NC strands with regularly and tightly stacked turns. Acutely infected L-41 or HEp-2 cells contained heteromorphous viral NC populations which included both typical and loosely packed NC. Persistently infected L-41 and Hep-2 cells predominantly contained NC of the latter type with the appearance of a "strings of beads".