Incorporation of radioactive seleno-(75Se)-methionine into mumps virus.

Mumps virus was grown in embryonated chicken eggs in the presence of radioactive seleno-((75)Se)-methionine. Virus in the allantoic and amniotic fluids was concentrated in a sucrose density gradient, and a peak of viral material coincided with a significant peak of (75)Se-radioactivity. The radioactivity was acid-insoluble and remained associated with the virus after purification by erythrocyte adsorption and elution and centrifugation on a second sucrose density gradient. After amino-acid hydrolysis of the radioactive virus, only (75)Se-methionine was recovered by chromatographic analysis. These results demonstrate that the radioactive (75)Se-methionine was incorporated into protein of infectious mumps virus.