Integration of measles virus nucleic acid into the cell genome

A system of chick embryo fibroblasts chronically infected with measles virus has been obtained, which supported production of the infectious virus in low titres. Virus-specific ribonucleoprotein (200S, 1.31 g/ml) is synthesized in this system and no mature virions can be detected. Hybridization experiments showed that measles virus DNA-transcript is integrated into the cell genome. This may be due to the presence of a latent oncornavirus in chick embryo fibroblasts. Possible relation of the model studied to subacute sclerosing panencephalitis is discussed.